FOCUS

BIODIVERSITY

C

NR

S P

hoto

thq

ue /

Nic

olas

Ceg

aler

ba. A

n ad

ult

hom

opte

ran

(Mem

brac

idae

), Fr

ench

Gui

ana.

The Centre National de la Recherche Scientifique (National Center for Scientific Research) is a government-funded research organization, under the administrative authority of Frances Ministry of Research.

CNRS IN BRIEF

FACTS

Founded in 1939 by governmentaldecree, CNRS has the following missions: To evaluate and carry out allresearch capable of advancingknowledge and ringing social, cultural, and economic benefits to society To contribute to the applicationand promotion of research results To develop scientific information To support research training To participate in the analysis of the national and internationalscientific climate and its potentialfor evolution in order to develop a national policy

CNRS research units are spreadthroughout France, and employ a large body of permanent researchers, engineers, technicians, and administrativestaff. Laboratories are all on four-year contracts, renewable,with bi-annual evaluations. There are two types of labs: CNRS labs: fully funded and managed by CNRS Joint labs: partnered with universities, other research organizations, or industry

As the largest fundamental researchorganization in Europe, CNRS

is involved in all scientific fields,organized in the following areas of research: Life Sciences Physics Chemistry Mathematics Computer science Earth Sciences and Astronomy Humanities and Social Sciences Environmental Sciences andSustainable Development Engineering Sciences

CNRS conducts some twenty interdisciplinary programs. Onemajor objective is to promote inter-disciplinarity in order toimprove knowledge, ensure economicand technological development orsolve complex societal problems.They concern the following fields: Life and its social challenges Information, communication and knowledge Environment, energy and sustainable development Nanosciences, nanotechnologies,materials Astroparticles

The CNRS annual budget repre-sents one-quarter of French publicspending on civilian research. This

funding comes from various sources: Government and public funding CNRS funds, primarily from industrial and EU research contractsand royalties on patents, licenses,and services provided.

More information at: www.cnrs.fr

CNRS pursues an active internationalpolicy, whose implementation is the responsibility of the Office of Europeanand International Relations (Directiondes relations Europennes et Internationales, or DREI).

The DREI coordinates the internationalactivities of CNRS with that of otherresearch organizations in France andabroad. It oversees the role of CNRS in any international actions carried out by the French government, working closely to this end with the Ministries of Research and Foreign Affairs.

The DREI also plays a role in promotinginternational exchange. It proposes newvenues for collaboration, based on a

science and technology watch in othercountries. This watch is carried out withthe help of CNRS offices abroad and ofscientific attaches in French embassies.

To accomplish its task, the DREI has offices in Paris responsible for four geographical areas (Europe; Americas;Africa and Middle East; Asia-Pacific) and 9 offices in foreign countries.

Contact: Isabelle Chauvel,isabelle.chauvel@cnrs-dir.frwww.drei.cnrs.fr

IN NUMBERS:

Exchange agreements: 80 (with 60 countries)Foreign visiting scientists: 5,000 (PhD students, post-docs and visitingresearchers)Permanent foreign staff members: 1,340 researchers of whom 54% comefrom the European Union 262 engineers and technicians International Programs for ScientificCooperation (PICS): 332 International Associated Laboratories(LEA + LIA): 54 International Research Groups (GDRE + GDRI): 56 International Joint Units (UMI): 9Budget for 2006: 10M

AND FIGURES

Budget for 20052,738 billion of which 494 millioncome from revenues generated by CNRS

Personnel26,000 permanent employees: 11,500 researchers and 14,500 engineers and technical staff

Organization 1,145 research and service unitsalmost 90% are joint laboratories 20 million devoted yearly to interdisciplinary research programs

Industrial Relations in 2005/2006 3,901 contracts signed with industry 35 framework agreements and 34 jointresearch units with industrial partners 132 million of revenues generatedfrom contracts (EU contracts notincluded) 7,450 Patents in CNRS portfolio (238 deposited and 239 PCT) 578 Active licenses 50 million of royalties 220 start-ups created since 1999DREI, AN OFFICE DEVOTED

TO INTERNATIONAL RELATIONS

SOMMAIRE

page 36

SUSTAINABLE MANAGEMENT

page 04

EDITORIAL

FOCUS

BIODIVERSITY

page 06

DEBATE

page 12

UNDERSTANDING BIODIVERSITY

page 18

ECOSYSTEM DYNAMICS

page 24

THE IMPACT ON HEALTH

page 30

BIODIVERSITY IN DANGER

page 43

BIODIVERSITY: A FEW STATISTICS

RESEARCH ON BIODIVERSITY

The huge variety of life on Earth is one of the great puzzles of modern science.Why do so many species coexist? Is such diversity inevitable given the laws of evo-lution? What is the history of life? How did species diverge and succeed one anoth-er over the course of evolutionary history? What impact have dominant species hadon the formation of todays environment? What role do they currently play in themodification of environmental processes? These questions have fascinated biolo-gists for many decades and are at the heart of one of the greatest intellectual adven-tures of our time. Since the Rio de Janeiro conference in 1992 biodiversity has alsobecome a social issue and its maintenance one of the major challenges for sustain-able development. Biodiversity needs to be protected and managed, but why? Thesimple answer to this question is that life on our planet depends on biodiversity.Humans draw upon it for the food and the raw materials necessary for their survival.

Biodiversity is a source both of concern and of hope. It is a source of concern dueto the incredibly fast rate at which species are vanishing today, which leads the gen-eral public, understandably, to ask about the seriousness of the situation. In scien-tific terms, this issue is fueling a huge debate about the functional value ofbiodiversity. For instance, we need to define the role that species play in the bio-physicochemical organizations of which they are a part, or put another away, theirposition in ecosystem structure and function. We also need to determine whether aminimum number of species is required for ecosystem survival and whether or notgenetic diversity plays the same role as species diversity with respect to ecosystemperformance.

These problems are not only of theoretical interest to ecologists. They also havea direct bearing on the quality of our environment. One only has to consider the keyrole played by biodiversity in what are called ecosystem services, i.e. the ecologicalfunctions listed in the Millennium Ecosystem Assessment, which affect the chemi-cal composition of water and the atmosphere, the spread of disease, etc. Or theresponse of ecosystems to climate change, which will depend above all on the num-ber of species present in a given ecosystem, the nature of the interactions and rela-tionships among the species, their ability to disperse and the impact of suchchanges on genetic variability. For instance, the amazing plasticity of genomes suchas microbial genomes represents an evolutionary response to the spatially and tem-porally variable environment in which humans live. The future of our planet will thusdepend on our capacity to manage this biodiversity.

Biodiversity is also a source of hope. Firstly, there is nothing inevitable about theloss of species. It can be slowed down or even halted by using innovative methodsof land management and species reintroduction based on the most recent researchfindings. Secondly, living organisms are an almost inexhaustible source of mole-cules of interest to the pharmaceutical and chemical industries, which every dayenable us to fight disease or produce a number of substances which are essentialto industry. Knowledge of natural substances, their variability and how they changein space and time is also an investment for the future. Finally, manipulating popu-lations of plants, animals or micro-organisms in situ makes it possible to rehabili-tate degraded environments or maximize certain of their characteristics orfunctions, depending on the environmental problems, as well as issues related tothe exploitation of natural resources, which arise.

THE ACTIVITY OF CNRS

CNRS, in partnership with universities, the Musum national dhistoire naturelle(French National Museum of Natural History, MNHN), Inra (National Institute forAgricultural Research), IRD (Institute for Research into Development), Cirad (FrenchAgricultural Research Center for International Development), Ifremer (FrenchResearch Institute for Marine Resources), and others, is totally committed to researchinto biodiversity. Aware of its responsibilities with regard to giving sustainable devel-opment a scientific basis, CNRS has made this issue one of its top priorities. In con-crete terms, CNRS encourages theoretical and empirical innovation in four broadfields: the analysis and management of biodiversity, mechanisms for the emergenceand maintenance of biodiversity, interactions between biodiversity and the environ-ment, and the cultural, social and economic aspects of biodiversity. CNRS developsthis activity on the basis of studies carried out in collaboration with researchers fromvarious regions of the world, especially French Guiana and the French overseasdepartments and territories, southern Africa (South Africa and Madagascar), Asia,etc. To this end, CNRS relies on ca. 2,300 people, of whom about a thousand are CNRSstaff members, both in its own laboratories and in laboratories associated with uni-versities and various partner organizations (MNHN, Inra, IRD, Cirad, Ifremer). All theresearch departments of CNRS are concerned by the issue of biodiversity because ofits multidisciplinary nature. The recently created Department of EnvironmentalSciences and Sustainable Development directly manages the laboratories which arethe most involved, looks after training and promotion of scientific activities in biodiver-sity, and organizes research and equipment development programs.

CNRS defines its policies in partnership with the other national bodies and insti-tutions. A body which has traditionally adopted an integrated approach is the Institutnational des sciences de lUnivers (National Institute of Earth Sciences andAstronomy), which plays a major role in financing research into the diversity of marineorganisms, interactions between the biosphere, the atmosphere and the hydrosphere,and paleobiodiversity. CNRS is also a member of two scientific consortiums, theInstitut franais de la biodiversit (French Institute for Biodiversity) and the Bureaudes ressources gntiques (Genetic Resources Institute), which regularly issue callsfor research proposals, represent France in a number of European and internationalbodies and propose national programs on different themes. CNRS contributes to var-ious bodies of the Agence nationale de la recherche (French National ResearchAgency), the main funding agency in France. It also supports European organizationssuch as the European Science Foundation via Eurocore Eurodiversity, as well as net-works of excellence such as Marine Genomics.

Some of the major challenges currently facing researchers are the long-termstudy of model populations, communities and ecosystems; the continuous monitoringof variations in the environment (including its biological aspects); modeling evolutionand ecosystem functioning; and experimenting on biological assemblages of varyingcomplexity. However, an ever increasing number of results published throughout theworld on the dynamics of biodiversity are based on technical facilities especially ded-icated to such approaches. There is therefore a strategic dimension to the develop-ment of such tools in France. CNRS gives financial support and provides staff fordiverse environmental research projects in specific areas where long term researchis being undertaken, an example being the experimental station at Nouragues inFrench Guiana. CNRS has also initiated an ambitious Ecotron program (one inMontpellier and one near Fontainebleau) whose objective is to conduct experimentalresearch on natural and artificial ecosystems within a confined environment.

Ren Bally and Luc Abbadie, Deputy Scientific Directors of the Department of Environmental Sciences and Sustainable Development

Bernard Delay, Scientific Director of the Department of Environmental Sciences and Sustainable Development

04-05

EDITORIAL

the Book of Genesis when Noah saveseach species by only keeping a singlecouple of individuals. Darwin revolution-ized the way we view this classification.He introduced the idea that diversity with-in species and diversity between speciesare of a similar nature. In other words,that diversity between species is simply adevelopment of diversity within species.

HERV LE GUYADER: Biodiversity can bedefined at three levels: biodiversity ofgenes, biodiversity of organisms andbiodiversity of ecosystems. What Pierre-Henri Gouyon has just said shows thatbiodiversity between species and biodi-versity between genes are totally con-nected. We should also remember thatall this takes place over time and inspace. We know little about species bio-

diversity; we havent described every-thing, and I believe that we know evenless about the biodiversity of genes andof ecosystems. We may thus have toprotect organisms that we dont knowmuch about.

MICHEL VEUILLE : The word "biodiversity"is recent. Our generation of taxonomists,geneticists and ecologists has seen achange in attitudes (in parallel with theemergence of an interdisciplinaryapproach to the study of biodiversity), bothwith regard to cultural and social aware-ness of biodiversity, as well as in the needfor increasing cooperation in research, asis shown by the creation of an interdisci-plinary department dedicated to the envi-ronment and sustainable developmentwithin the CNRS.

Michel Veuille is Directeur dtudes at the colepratique des hautes tudes, Director of the Taxonomyand Evolution Department at the Musum nationaldhistoire naturelle and Director of the ResearchNetwork for Population Genomics.

Pierre-Henri Gouyon is a professor at the Musumnational dhistoire naturelle (French NationalMuseum of Natural History), at INA-PG and at thecole polytechnique. He is a researcher at theLaboratory for Functioning and Evolution ofEcological Systems.

Herv Le Guyader is a professor at the Universityof Paris 6, and Director of the Research Unit forTaxonomy, Adaptation and Evolution.

06DEBATE

DESPITE ITS POPULARITY, THE CONCEPT OF BIODIVERSITY IS COM-PLEX. TO DEMONSTRATE THE WIDE RANGE OF QUESTIONS IT RAISES,FIVE RESEARCHERS IN ECOLOGY, TAXONOMY, GENETICS, ETC GOTTOGETHER WITH REN BALLY, DEPUTY SCIENTIFIC DIRECTOR OF THEENVIRONMENT AND SUSTAINABLE DEVELOPMENT DEPARTMENT ATTHE CNRS. IN WHAT FOLLOWS WE REPORT THEIR DISCUSSION, WHICHALTHOUGH CONTROVERSIAL AT TIMES, IS INSTRUCTIVE THROUGHOUT.ROUND TABLE WITH LUC ABBADIE, ROBERT BARBAULT, PIERRE-HENRI GOUYON, HERV LE GUYADER AND MICHEL VEUILLE.

WHAT IS BIODIVERSITY?

PIERRE-HENRI GOUYON : Humansbecame aware of biodiversity very earlyon. The idea of classifying the untidy,messy thing called Nature was bound tocatch on. Living things are classified inevery known culture. The way theyreclassified, however, varies from one cul-ture to another.

Our initial view of biodiversity was exclu-sively based on classification by species.Linnaeus stated that all species were cre-ated by the hand of an all-powerfulCreator, and that when these speciesreproduced they remained confined totheir own type. He gave no credit to theimportance of within-species variability.That was the Western view of the world inthe 18th century. You find the same view in

06-07

DEBATE

ROBERT BARBAULT : I believe that theword "biodiversity" first emerged withinthe context of the Rio Conference,although the word was actually used sev-eral years earlier in scientific circleswhere the talks were being organized.From 1992 onwards, the entire scientificcommunity has adopted the word "biodi-versity".

MICHEL VEUILLE : The word biodiversity isan extremely valuable portmanteauword. It reflects our ignorance. Linnaeusknew of about forty thousand species.Today, more than a century after Darwin,about 1.8 million species have beendescribed. We know that there exist fiveto ten times as many organisms tradi-tionally described as animals and plants,in other words between 10 and 15 mil-lion. We are only acquainted with a tinypart of the biodiversity of bacteria andfungi. It is currently thought that we onlyknow about 5 to 10% of fungi. We dontreally have the research capability need-ed to discover all these species. Whenresearchers from the National Museumof Natural History explore an area in thePacific they find that 20% of the mollusksthey bring up from the sea floor are newspecies.

PIERRE-HENRI GOUYON: Can we create aconcept of biodiversity which integratesboth diversity within species and diversi-ty between species? We dont know howto do that today. But this is a good time tostart working on it. To construct phyloge-niesto understand the evolutionaryrelationships among specieswe cannow use gene coalescence. In this waywe can take into account genetic diversi-ty in the study of diversity betweenspecies. 150 years after Darwin, wouldntit be possible to create an authentic con-cept of biodiversity which combinesgenetics and taxonomy?

LUC ABBADIE : It could go further andintegrate the functional aspects whichregulate the interactions between theorganization of life and the flow of mat-ter and energy and, more generally, theenvironment. There has been a lot ofwork done on the functional value ofbiodiversity, practically all of it atspecies level. Very little notice has beentaken of the functional consequences ofgenetic diversity. However, life variesalong a continuum from the gene,through the species, to the communityof organisms.

There exists a positive connectionbetween biodiversity and the productivityor stability of an ecosystem. And yetsome very old and very productiveecosystems are lacking in species. Insuch systems enhanced genetic diversitymay "substitute" for low species diversi-ty. Any such functional equivalencebetween intraspecific (genetic) and inter-specific diversity remains to be explored.

PIERRE-HENRI GOUYON: Theories deter-mine our descriptions. Linnaeus andDarwin had different views of biodiversitybecause they had different mechanismsin mind. We should give up the idea thatwe can describe nature without havingany theories about the way biodiversityhas evolved.

MICHEL VEUILLE : Its obvious that if wehad a theory which explained why thereare so many species, it would also be atheory that would better explain ecosys-tem functioning and how we can pre-serve third order biodiversity, i.e. that ofpopulations and ecosystems. This orderdetermines many things.

HERV LE GUYADER: Lets be clear aboutthis. We dont have a theory, but there is

nonetheless a conceptual framework:the theory of evolution. Darwin showedthat when there is selection, diversityincreases.

PIERRE-HENRI GOUYON: Although wehave a conceptual framework, we wouldonly really get a handle on the problem ifwe were capable of saying what process-es determine the number of genotypesand species. We know what the process-es are, but we dont know how to organ-ize them in order to explain whats goingon at the level of the planet.

ROBERT BARBAULT : By looking at biodi-versity from an ecological angle we canattempt to answer these questions.Besides kinship relations and geneticvariability, there are selective pressures.The ecological context produces theseand enables us to understand why thereis a build-up of diversity, and why, aftereach extinction crisis, biodiversity re-establishes itself. We live in a world thatis constantly changing on all scales. Sothere are no species which are adaptedto all the conditions on the planet. Onthat basis, just as for genetic approach-es, we can gradually improve our under-standing. Thats why, when I talk aboutthe diversity of life, I tend to start off at aglobal level. What is the diversity of life?Its the living fabric of the planet, of whichwe are part, which is made up of speciespossessing enormous genetic variability.Its a fabric of countless interactionswhich evolve in a changing world. Thereason diversity exists is the need toadapt to unceasing changes in space andtime.

HERV LE GUYADER: We can look at bio-diversity from three different levels.Pierre-Henri Gouyon started off by talk-ing about species. Robert Barbault seesit at a planetary level, as a fabric of inter-actions. If we had a hard-line molecularbiologist here, they would probably beginwith the genome and end up with thediversity of genes. All biologists, whatev-er their starting point, eventually end upat this concept of biodiversity.

Robert Barbault is a professor at the University ofParis 6, Director of the Institute for Ecology,Biodiversity, Evolution and Environment and Directorof the Department of Ecology and BiodiversityManagement at the Musum national dhistoirenaturelle.

Luc Abbadie is a professor at the University ofParis 6 and Director of the Research Unit forBiogeochemistry and Ecology of TerrestrialEnvironments (Bioemco).

DO WE NEED TO PRESERVEBIODIVERSITY?

MICHEL VEUILLE : People are becomingever more aware of the fragility of nature.Until recently, many biologists thought in terms of equilibrium when theyconstructed a model of populationgenetics.

For these biologists, before humansmade their considerable impact, andwith the exception of a few post-glacialfluctuations, nature was in balance. Itwas invulnerable. Nowadays we knowthat this does not apply to the recent his-tory of biodiversity. We know that evenbefore the Neolithic, when humans firststarted to have a significant influence onnature, there had been extinctions.

PIERRE-HENRI GOUYON: The idea thatspecies can become extinct is a new one.It was Cuviers idea and is only 200 yearsold. It took us a long time to assimilate it.

Many people say that the image of theEarth seen from the Moon played a keyrole. Today, the notion of the blue planetis meaningful for everyone.

MICHEL VEUILLE : Aside from the moralquestion posed regarding the conserva-tion of the whole living world in existencetoday, some people are wondering if somany species are necessary for function-al groups, or whether coral reefs reallyneed all those butterfly fish (pantodonbuchholzi), etc. Granted, there are 15million species, but we have never beenaware of the existence of most of them.Do we need to keep them all? Are they alluseful for the preservation of ecosys-tems?

PIERRE-HENRI GOUYON: I am one ofthose who think that there is actually noecological need to have a huge amount ofbiodiversity. I believe that there areenough species, and enough genotypesfor species, to keep things ticking overnicely. But thats a personal impression. Icant prove it. Nor can those who thinkotherwise.

ROBERT BARBAULT: Theres no proof, butthere is nonetheless some evidence for it.

PIERRE-HENRI GOUYON : For me, thequestion is above all a moral one. Im infavor of the preservation of biodiversity.Were making a moral problem depend-ent on a scientific result. Its the samething as saying that you shouldnt beracist because there are no genetic dif-

ferences between ethnic groups. But ifwe did find a genetic difference, wouldthat mean that we could be racist? Theproblem is to know what role the humanspecies sees itself playing in the man-agement of the Earth. This questionshould be kept separate from that ofknowing whether we need lots of specieson the grounds of ecology or sustainabil-ity. Yes, Im in favor of preserving biodi-versity, first of all on moral grounds, andthen, if there are practical, concrete rea-sons as well, so much the better.

LUC ABBADIE : I agree with you, there arefirst of all moral grounds for preservingbiodiversity. But there are also moreobjective reasons. If I go back to whatweve just been saying, current biodiver-sity is basically the result of a piling up ofpast events, of a series of reactions ofeach species to pre-existing environ-ments and to the presence of otherspecies. Certain organisms were abun-dant at one time. They are less so today,but they might make a massive come-back, depending on changes in the envi-ronment.The time scale is important. Some scien-tific results can be, and are, wronglyinterpreted. You hear conclusions suchas There are many species which serveno purpose Ecosystems could functionwith fewer species. The trouble is thatwe only see a snapshot of biodiversity. Aspecies which today appears redundant,not essential, might become vital to theecosystem in some future phase becausethe environment will have changed,

Photograph of the Earth as seen fromspace (1968). For many people, seeing theEarth as it looks from space made them

question the idea that nature is all-powerfull,and to assimilate the ntion that nature is fragileand that species can disappear.

Only a tiny proportion of the worlds speciesare known. 1,600 marine species arediscovered and described every year. Tropicalregions, and especially coral reefs, areexceptional reserves of unknown species.During six weeks of intensive fieldwork, thePanglao Marine Biodiversity Project (Musumnational dhistoire naturelle/Universiy of SanCarlo/National University of Singapore)discovered several hundred new species ofshellfish, and nearly a thousand new speciesof mollusk.

N

ASA

/ S

cien

ce P

hoto

Lib

rary

P

ierr

e Lo

zoue

t, M

arin

a P

oddu

bets

kaia

et

Stef

ano

Schi

apar

elli

- Pa

ngla

o M

arin

e B

iodi

vers

ity P

roje

ct

08-09

DEBATE

result. The high degree of disturbance inSouth America formed refugia, and thatwas certainly the reason why biodiversityincreased. Disturbances can have com-pletely opposite effects depending ontheir type.

HOW CAN WE MANAGE BIODIVERSITY?

MICHEL VEUILLE: Id like to come back tothe little blue globe on which humans,together with biodiversity, are travelingthrough space. Since humans take up alot of room, theres less room for biodi-versity. The spread of invasive species isanother factor which is eroding biodiver-sity. Those which are human-commensalspecies displace native or endemicecosystems by installing a kind ofMcDonalds ecosystem, which were soongoing to be finding in every corner of theplanet.In a certain way, humans are now manag-ing biodiversity like a garden. Until now,biodiversity was self-sufficient.Henceforth it will only exist insofar as weleave it the room to do so. With regard tobiodiversity, humans are a bit like some-one whos packing a suitcase and whohas to decide what to take. Should youtake a wide variety of different types ofclothes, or a large number of clothes ofsimilar type? Should we keep many

because it will have rained a little bitmore or less, for instance.Biodiversity is a storeroom of responsesof living things to changes in the environ-ment, which have been tested in the pastover thousands and millions of years. Ifwe reduce the content of this storeroom,there will be a gap between the varia-tions in the environment and the range ofpossible responses. Every species hasprobably had, at one moment or another,a major impact on the environment. Thenotion of key species is a dangerous one,since a given species is only critical("key") at a particular moment in time.

HERV LE GUYADER : The Earth hasextraordinary stability. At the end of thePermian, 80% of species vanished, andyet this disturbance was absorbed. Wevealways wondered why biodiversity, in thewestern Pacific for instance, is far greaterthan in the Mediterranean. Yet again its aquestion of stability. Tropical ecosystemshave been very stable from an environ-mental point of view, whereas in theMediterranean, whether were talkingabout glacials or about the evaporation ofthe sea during the Neocene, there weremajor fluctuations. Biodiversity frequent-ly declined suddenly and never returnedto the level found in tropical ecosystems.Thats one possible interpretation.

PIERRE-HENRI GOUYON: Events such asthese dry periods were widespread. If youcompare the diversity of plants in Africaand South America you find the opposite

species, each with little genetic variabili-ty, or should we keep few species, eachwith a great deal of genetic variability, sothat they have the most chances of evolv-ing? We dont yet have the conceptualtools to answer this kind of question.

PIERRE-HENRI GOUYON: We all agree thatthis conceptual work needs tobe done. That said, once wehave the answer, the questionwill no longer be stated in thesame terms. You dont managebiodiversity in the same way asyou pack a suitcase. Oddlyenough, its the most deter-ministic sciences from whichwe can learn. Today, physicistsand chemists who are workingin nanotechnology get objectsto self-assemble in order tomake systems, rather than try-ing to make each element in

the system one after another. In evolution-ary biology and in the ecology of biodiver-sity, where everything is interaction andwhere we work with very complex sys-tems, were still wondering whether weshould keep species X or species Y. We allwork with this concept of self-organiza-tion even if we dont always realize it. Wecan try to manage the whole self-organ-ized system, but certainly not eachspecies one by one.

ROBERT BARBAULT : The expression"managing biodiversity" is totally exces-sive when you look at what we are capa-ble of. On the other hand, we canestablish rules for preserving the diversi-ty of large ecosystems without having tointervene within those ecosystems.In nature, there are parasites andpathogens as well as food resources andmedicines. So its a struggle. But its ajudo-style struggle, which relies onforces that already exist. In this way,there can be an adjustment of the rela-tionship between the development ofhuman societies and the preservation ofa biosphere in good working order.However, to imagine that were going tobe running things as if we were somekind of planetary super gardeners is noton the cards.Theres a difference between what wehave to do and what we decide to do. Wehave to decide what kind of society we

Mediterranean and Pacific sea floors. Tropicalecosystems have undergone little disturbance,which is why biodiversity is greater there than inthe Mediterranean.

C

NR

S P

hoto

thq

ue /

J.L

ecom

te

Ale

xis

Ros

enfe

ld /

Sci

ence

Pho

to L

ibra

ry

want. We could single out showcaseareas of biodiversity such as coral reefs,and focus all our efforts on preservingthem. As if the diversity of the tundra orof Europes cold regions, which get lessmedia coverage, were of no interest tothe people who live there! We should trynot to confuse scientific analysis withsocial or political choices.

LUC ABBADIE: Management basicallyinvolves setting up a partially artificialsystem which we think we can control.However, we dont have the intellectualmeans for this control. Let me take aspecific example, that of farming sys-tems. They often perform poorly despitebeing supplied with huge quantities ofenergy and nutrients. The reason for thisis that we have changed some of theplayers and some of the processes with-out verifying that these alterations fit the

overall logic of the ecosystem. This logicis difficult to detect: natural systems,which are sustainable, diversified andproductive, provide an ideal situation todefine the proper logic.Although we now more or less under-stand the principles of evolutionarymechanisms, the subsequent interac-tions that they generate are hugely com-plex. Throughout the history of theplanet, a vast number of "biodiversity-environment" scenarios have been test-ed and live on in the way biodiversity is

currently organized. I think we shouldtry to preserve this potential, even

though Im also a keen supporterof ecological engineering. Thereare natural models which wewould do well to think about.

HERV LE GUYADER: Here arethree current examples ofaction being taken for biodi-versity conservation. First, theApple-eaters Association.What are they doing? Well,theyre in the process of "sav-ing" all the varieties of applewhich are disappearing. Here

were talking about intraspecificvariability, i.e. within one

species.Some people fight to save dolphins

and whales. They focus on onespecies, usually a charismatic one,

because its big, its beautiful and itspretty exceptional.Lets take a third example: the Austra-lians and the Great Barrier Reef. Nowimagine that the fish in the coral reefswerent as brightly colored. Im not surethat wed hear about them as much.I chose these three examples becausethey represent the three levels of biodi-versity. Its obvious we could never "man-age" all the species in the way theApple-eaters do. Actually, coral reefsreally are showcase ecosystems, but thatdoesnt mean that the tundra ecosystemis any the less extraordinary.

BIODIVERSITY: ETHICAL VALUEOR ECONOMIC VALUE?

PIERRE-HENRI GOUYON: I compare theethical issue of biodiversity with theissue of the death penalty. You can find alot of rational arguments in favor of the

death penalty. But a society which givesitself the right to kill people is simply asociety which devalues itself. As far asIm concerned, a society which gaveitself the right to destroy all the livingspecies which were of no use to it wouldbe in the same category. We can talkabout the usefulness of biodiversity tohumans and I think that its a goodthing to talk about it but thats not themain issue. The most important thing ishow we see ourselves in our relationshipwith nature, from which we came, and towhich we belong. Today, we live in asocial, economic and political systemwhich has trouble taking this kind ofdimension into consideration. Unless wesucceed in giving ethical values an eco-nomic value, I fear that the attitudewhich consists in systematically givingeverything, including biodiversity, aneconomic value wont let us take intoaccount the most fundamental dimen-sion of this question.

MICHEL VEUILLE: Since 1992, the RioConvention on Biological Diversity hasgiven us a framework for thinking aboutbiodiversity which is different from anabsolute or, if you like, philosophical one.The interesting thing about the Conventionwas that it brought together nations whichsee biodiversity in different ways: as anesthetic resource, as a material resourceor even as a potentially economicresource. The Rio Conference made it pos-sible to think about these issues collec-tively, to escape from the sterilediscussion about the value of biodiversityper se, and in so doing confront us withour responsibilities.

ROBERT BARBAULT : I think that the firstthing that should be said when someoneasks what biodiversity is for an irritat-ing and poorly formulated question,because they dont say what biodiversityshould be for is that the diversity of theliving world is the result of four billionyears of evolution. Species have inventedquite a few things. Over several millionsof years, they have been solving prob-lems in order to survive, to reproduceand so on. That should earn our respect.Any wanton destruction of them is anattack on our own status as the humanspecies. Once youve said that, youvemade the fundamental point. Then youcan say that we depend on the diversity of

Gold medal struck in India the elephantmoving to the right, eastwards, is a directreference to the conquest of India and to thevictory over the elephants of Porus in 326 BC.

living things and on all the interactionsthat it entails. We depend on it not onlyfor the esthetic and spiritual values thatare associated with it, but also for food,for health and so on. It isnt necessary togive everything an economic value. Somepeople are worried about the disappear-ance of species. First of all, it isnt total-ly irreversible. In fact, the biodiversitycrisis is an opportunity for the humanspecies to react and to reconsider itsgoals regarding development. Thisbrings us back to the need for lasting,sustainable development, except that forthe moment its more a case of "letshope it lasts" development.

LUC ABBADIE : Biodiversity is a symbol ofsustainability and adaptability. Our modeof development is not sustainablebecause it is not adapted to the finitenature of resources and because itignores the role that other species playin the regulation of our environment.Civilization has reached a real crisispoint. We have to re-think the world; inthis respect, the history of life could pro-vide some good ideas.

ROBERT BARBAULT : The ecological serv-ice concept, irritating though it is,nonetheless has the merit of makingpeople understand that certain thingswhich are important for our well-beingmay not be subject to market forces, andthat they can deteriorate to the point thatit becomes essential to take technicalmeasures to replace them. This can bean extremely expensive business. The

large water companies are well awarethat it is cheaper to preserve the qualityof ecosystems, and therefore biodiversi-ty, than to build and maintain huge watertreatment plants.

PIERRE-HENRI GOUYON: You often hearpeople say, Scientists will find a solu-tion. Here I think its important to saythat were not going to find the solutionthat people are expecting. We have a the-oretical solution to the problem, but thissolution isnt the one that people arehoping for. Its more about regulatingconsumption, expenditure and so on.

MICHEL VEUILLE : Like Socrates wouldsay, the first act of reason is to be awareof ones own ignorance. Science cant doeverything, and in particular it cantaccurately predict the future, eventhough one of its roles is to enlighten thepublic about future changes. The otherarea of society where predictions aremade is in politics. You can always go onabout unkept promises, and about theactual consequences of what politiciansdo. Nevertheless, when you put all thosepolitical acts end to end the result iscalled History. Somehow or other, itmarches on. Thats more or less theimage of what we can modestly hope tohave during the 21st century to preservebiodiversity. However, whatever we do ordont do, consciously or not, whether itbe interventionist or laissez-faire, will bedecisive for the preservation of biodiver-sity. Science still underpins our thinking,even though we need to oppose absolute

faith in science.PIERRE-HENRI GOUYON: That applies totechnology more than science!

HERV LE GUYADER: Id like to comeback to the problem of the notion of time.In the 18th century, foresters managedthe forest for future generations. Theygrew oaks to make ships. They knew theywould never see the oaks that wereplanted used during their own lifetime.Today, politicians only think in terms ofthe next few years, i.e. until the next elec-tion.

MICHEL VEUILLE : Biodiversity is charac-terized by its cross-disciplinary nature,which is now also true at CNRS. Butobviously, for it to be cross-disciplinarythere has to be something there for it tocross! In fact, there are scientific founda-tions to this cross-disciplinary field. Theinteresting thing about an institution likeCNRS is precisely that it combines fun-damental research with a cross-discipli-nary approach which brings everythingtogether.

10-11

DEBATE

THE CONVENTION ON BIOLOGICAL DIVERSITY

The Convention on Biological Diversity is a historic commitment. It is the first treaty concluded at worldlevel which tackles all aspects of biological diversity. It concerns not only the protection of species butalso of ecosystems and the gene pool, as well as the sustainable use of natural resources. It is the firsttreaty to recognize that the conservation of biological diversity is a common concern of humankindand that it is an integral part of any sustainable socio-economic development. Open for signature at the Earth Summit, at Rio de Janeiro, 5 June 1992. Came into force on 29 December 1993, 90 days after the 30th ratification. Ratified by 188 countries.

A caterpillar, Vettius tertianus, at the finalstage of development. This caterpillar is aparasite in gardens inhabited by the antPachycondyla goeldii.

C

NR

S P

hoto

thq

ue /

Jr

me

Ori

vel

Kiwa hirsuta was discovered by aresearcher at Ifremer in March 2005. Duringthe first weeks of March 2006 the mediaquite unexpectedly took the story up. Withina few days, the number of pages about thisanimal on the Goggle search engine jumpedfrom a mere handful to 200,000.

12UNDERSTANDING BIODIVERSITY

FROM GENETIC VARIABILITY TO THE WEALTH OF FAUNA AND FLORA,FROM THE DIVERSITY OF SPECIES TO THE DIVERSITY OF ECOSYSTEMSAND LANDSCAPES: UNDERSTANDING BIODIVERSITY MEANS FIRST OFALL IDENTIFYING, LISTING AND CLASSIFYING THE BIOLOGICAL ENTI-TIES THAT MAKE IT UP. IN ADDITION IT ALSO MEANS ANALYZING THEGENETIC STRUCTURE OF THEIR POPULATIONS, RECREATING THEHISTORY OF EVOLUTIONARY LINEAGES AND UNDERSTANDING THEEFFECTS AND SCOPE OF PHENOTYPIC PLASTICITY. FINALLY, ITMEANS INVESTIGATING THE WEALTH OF INTERACTIONS AMONGSPECIES, WHICH MAKE UP THE ECOLOGICAL FABRIC OF WHAT ISPROPERLY CALLED BIODIVERSITY DYNAMICS.

HOW MANY SPECIES ARE THERE ON EARTH?

From time to time, the announcement of the discovery of a plant or an animalbecomes widely reported in the media, rather than remaining confined to specialistcircles. For instance, the discovery of both the worlds smallest vertebrate,Paedocypris progenetica, a fish from the mangrove swamps of Sumatra less than eightmillimeters long, and a species which represents a new family of crustaceans fromthe Eastern Pacific, Kiwa hirsuta, have received a great deal of media coverage.

Away from the spotlight of the media, the inventory of our planet continues, with16,000 new species described every year. Even in Europe, new species continue to bediscovered, with 600 descriptions of animal species being added per year, a rate thathasnt slowed down since the beginning of the 20th century. In fact, the only thing thatweve become sure of in the last twenty years is that the total number of living speciesis one, or even two, orders of magnitude greater than the 1.8 million species alreadydescribed. Tropical forests, coral reefs, the large ocean basins and parasites as awhole make up the main reserves of unknown species. For unicellular eukaryotes,new types of organization (new classes and orders) doubtless remain to be discovered.Completing the inventory of vertebrates, phanerogams and a few rare groups of inver-tebrates (butterflies and odonates) is no doubt by and large within our reach with thehuman resources at our disposal. For most groups, however, the human and method-ological means needed to describe species diversity is woefully inadequate, and willalso need to be upgraded by one or two orders of magnitude.

At the current rate at which new species are being listed, most of them will havebecome extinct before they can be described and named. Viewed in this light, althoughthe molecular revolution drastically altered the taxonomy of prokaryotes as early asthe 1970s, its contribution to the taxonomy of eukaryotes currently remains marginal.The impact of international initiatives such as the Bar code of Life, which consists insequencing the gene that codes for Cytochrome oxidase 1 in order to recognize andseparate species, is still a subject of debate among the scientific community.

If

rem

er /

A. F

ifis

12-13

UNDERSTANDINGBIODIVERSITY

Ais

topo

daN

ectr

idea

Lyso

roph

ia

Dia

dect

omor

pha

Mes

osau

ria

Par

eias

auri

aP

roco

loph

onia

Youn

gini

form

es

Apo

daU

rode

laA

nura

Syna

psid

a

Chel

onia

Lepi

dosa

urom

orph

a

Amphibia

Tetrapoda

ReptiliomorphaAmniota

SauropsidaParareptilia

Eureptilia

Arc

hosa

urom

orph

a

Mic

robr

achi

sR

hync

honk

os

Jurassic

Triassic

Pemnian

Penn.

Mississi.

Devonian

144

213

248

286

320

360

408

HOW CAN SPECIES BE CLASSIFIED?

Given the huge number of living species, biodiversity can only be made sense of byusing concepts. The role of classifications is to create these concepts as well as wordswith generally accepted meanings. Classifications are arbitrary. Their function is tomeet pre-established specifications. Objects are grouped together in order to accountfor certain specific properties: for example, our culinary needs (seafood, game, etc.).In the field of biological sciences, the aim of a classification can also be to creategroups which reproduce the unity of species as regards their functional relationshipsin environments (e.g. phytoplankton, zooplankton). A good classification accounts forproperties which have been agreed on.

Over the last 150 years, within the framework of the theory of evolution, the goalof taxonomy (the science of classifying species) has been to create concepts known astaxa which reproduce the relative degrees to which species are related to each other.For a century, phylogeny has been the "tree of life" which depicts these relationships.The role of taxonomy is not just to identify species and give them names. It piecestogether kinship relationships on the basis of comparative anatomy and by comparinghomologous genes. On a phylogenetic tree, each branch of the tree is given the nameof a particular taxon, and contains all the subsequent branches. A phylogenetic clas-sification is a system of taxa nested within one another. We have only been able to cre-ate such phylogenies for about fifty years.

This way of classifying living things represents the culmination of a trulyCopernican revolution, the seeds of which were already to be found in Darwins ideas.Rather than reflecting the central place in the Universe that humans liked to thinkthey had, it revealed the degree to which all living beings are related.

A DIVERSITY FIRMLY ROOTED IN GENETICS

Most of the mechanisms which can be used to explain diversity with regard to specieschance, natural selection and migration also operate at the level of populations.Mutations, which take place randomly in the genome of individual organisms, provide thebasic variation on which the other evolutionary forces can work.

Phylogeny of tetrapods.

STRATEGIC DATA BASES

Just as with meteorology, modeling and predicting biodiversity is possible as long as large sets ofspatial zed data on species are available. By superimposing the geographical coordinates of theoccurrence of species on maps of climate, geology, ecology, etc., it is possible to calculate thepotential distribution of species on the basis of their observed distribution. For instance, by varyingthe climatic parameters according to the various existing models, it is possible to predict the possibleevolution of local biodiversity under the influence of climate change. Experimental data of this kindhas accumulated in museum collections over the last two centuries such as the specimens in the

herbariums at the Musum national dhistoire naturelle (the French National Museum ofNatural History, www.mnhn.fr) and, much more recently, in data bases of environmentalobservations (inpn.mnhn.fr). In order to build the infrastructure which will make itpossible to utilize all this data which is scattered among countless institutions, thetechnological and scientific challenge is to make existing data bases interoperable. Inthis way, any user will be able to utilize the data as if it were stored in a single database.Computer software for this will be made available to potential users. To achieve thisgoal, several international groups are working within an international network known asGBIF (Global Biodiversity Information Facility, www.gbif.org), with a view to clarifying ideasand creating software that will enable all this disparate data to be used.

G

BIF

M

iche

l Lau

rin

THE MOLECULAR MARKERS OF THE HISTORY OF SPECIES

A species history leaves traces in its genes. In the last few years, researchers havemade a spectacular leap forward in interpreting this molecular information.Population geneticists are now able to enumerate the genes which bear the "signa-ture" of natural selection or of demographic events (see Figure 1). For cultivatedplants, for instance, it is possible to detect the genes which bear a domestication syn-drome, a record of the artificial selection carried out by early farmers.

Over the course of generations, mutations appear in a gene. The same gene canthus be found in the genome of individuals from the same species in different forms.Over the past twenty years there has been enormous progress in interpreting thispolymorphism of DNA sequences. "Coalescence theory", together with the develop-ment of new bioinformatic tools for data analysis has made it possible to interpret thephylogeny of genes in a single species. Population geneticists have used these tech-niques to model the colonization of Europe by modern humans. Their model incorpo-rates the geography of Europe and the growth of populations.

Inras laboratories have studied the recent spread through Europe of an invasivespecies of corn pest. They have discovered the origin of the invasion. It is the result ofthree different introductions of individuals from North America. The next challenge forpopulation genomics (see Figure 2) is to develop a molecular signature for eachspecies. This taxonomic information will then be of benefit to the whole scientificcommunity.

GENETIC DIVERSITY AND STRUCTURE OF POPULATIONS

In order to characterize genetic variability, certain biochemical or molecularmarkers are used. Markers with a single genetic determinism, whose variation is dis-continuous, are mainly used to "identify" gene flow between individuals (reproductivesystems on a local scale) and populations (reproductive systems on a regional scale).They frequently consist of fragments of DNA of unknown function, whose variability isapparently neutral with respect to natural selection. Phenotypic features the visiblecharacteristics can also be used to characterize genetic diversity. They are oftennonneutral with respect to natural selection.

We therefore use certain phenotypic characters which show continuous variation,for whom the genetic determinism of the variation is frequently complex, and whoseexpression is heavily influenced by the environment in which it is observed. The evo-lutionary success of different phenotypes depends on the environment, so much sothat it is possible to observe phenomena of local adaptation. Migration and mutationhave opposing effects on this local adaptation. These two evolutionary forces intro-duce variation, on which natural selection can then act. When populations are smallin size, natural selection becomes less effective. By chance, harmful mutations maybecome more frequent and lead to populations becoming less viable. This is what iscalled genetic load or inbreeding depression.

Consider the example of the island cabbage, Brassica insularis, a protected speciesendemic to the islands of Sardinia and Corsica. This species has a self-incompatiblereproductive system. Two cabbage plants having the same allele at the self-incompat-ibility locus cannot breed. Besides the monitoring of populations carried out since1999, molecular diversity, the diversity of quantitative characters and diversity at theself-incompatibility locus have also been studied. All the results show that the popu-lations are small in size, and have low genetic diversity and that there is a quasi-absence of gene flow among populations. Whats more, one of the populations showsparticularly reduced diversity at the self-incompatibility locus. Hence, little cross-breeding is possible among individuals in this population. The question here is as fol-lows: is it better to reinforce this population, at risk of making it lose its geneticidentity, or to let things be and hope for the appearance of mutations at the self-incompatibility locus? The answer has yet to be found

Population of constant size

Expandingpopulation

Tim

e

Ancestralspecies

Daughterspecies A

Daughterspecies B

Isolation

Speciation

Figure 2. The molecular signature intaxonomy, or bar-code, is a simple systemfor characterizing species. When populationsof the same species divide, giving rise todifferent species, some polymorphisms ofthe ancestral species are fixed, by chance orby selection, in one or other of the daughterspecies (mutations are represented bycircles). The diagnostic mutation is shown inblue. This mutation appeared in the commonancestor of all the sequences of daughterspecies B. They are the basis of themolecular "bar-code". However, not everymutation leads to a new species.Collaboration between geneticists andtaxonomists is vital if we are to define auniversal bar-code system.

Tim

e

Figure 1. Molecular signature of pastdemographic events. In a population, thesequences of the same gene (here, sixsequences represented by squares) havecommon ancestors (represented by circles).In a population of constant size, many ofthese ancestors are recent, while a smallnumber are distant. In contrast, in anexpanding population, most of the commonancestors date from the beginning of thepopulations history, and are comparativelydistant. The phylogeny of genes withinspecies thus gives us information about thehistory of populations.

Population of the cabbage Brassica insulariscalled Conaca. Not only does the reducedgenetic diversity at the self-incompatibilitylocus result in a reduction of the proportion ofcompatible crosses, but moreover, selectivepressure for resistance to flower parasites isundoubtedly weakened, precisely because ofthe low rate of reproduction in this population.This is why attacks by parasites are morepronounced in this population (in this case byaphids) than in the other populations on theisland.

14-15

UNDERSTANDINGBIODIVERSITY

DIVERSITY: BEYOND GENETICS

Although genetic diversity is the chief source of diversity among individuals of agiven species, some types of phenotypic diversity are not necessarily associated withgenetic differences. For instance, plasticity enables two individuals with the samegenotype to have a different phenotype depending on their habitat, and thus be betteradapted to their environment. The amount of such plasticity depends on the individualand on the species.

Other mechanisms, such as developmental instability, can lead to greater pheno-typic variance. This random variability may be adaptive in an unsettled, unpredictableenvironment. This, for instance, is the case for the flowering period of gorse, Ulexeuropaeus.

Lastly, a gene can undergo different kinds of regulation during transcription (trans-formation of a DNA sequence into RNA). The same genotype can therefore give differ-ent phenotypes. It can undergo epigenetic variation, in other words hereditary changeswhich are not coded for by DNA. These may be the chief source of diversity, as wasshown by a team from the Ecobio Laboratory for the invasive clonal grass Spartinaanglica. Understanding biodiversity thus makes it necessary to take into account thewhole of diversity, whether it be deterministic or random, hereditary or not, that can begenerated by the same genotype.

The genetic variability and genetic evolution of a population are very complex. Thereare a large number of phenomena at work, of which we know but a few. The geneticbiodiversity which they give rise to is indeed considerable. We now need to incorporatethese phenomena at the ecosystem level. Their relationships with the environment, theinteractions among species and the evolution of these relationships over time are alldimensions that need to be taken into account if we are to understand ecologicaldynamics.

These two individuals of Ulex europaeus, ofidentical age and grown under the sameexperimental conditions, do not flower at the

same time. This experiment demonstratesintraspecific variation in flowering.

A

nne

Atl

an/E

cobi

o 20

06

C

NR

S P

hoto

thq

ue /

Isab

elle

Oliv

ieri

The aquatic mollusk Biomphalaria glabratais the obligatory intermediate host of theparasite Schistosoma mansoni.

BIODIVERSITY SHAPED BY A NETWORK OF INTERACTIONS AMONG SPECIES

Interactions among species are both numerous and complex. They play one of themost important roles on the biodiversity stage.

Parasites, for instance, and more generally symbionts, are an integral part of bio-diversity. It has even been shown that groups which have adopted a parasitic way oflife have become more diverse than free groups. This is a demonstration of theextremely dynamic nature of durable interactions. Parasites are often dominant onthe "selective stage". They alter population dynamics and the evolution of freespecies. They can play a predominant role in the success or failure of a biological inva-sion.

The success of an invasion of a new area by a free species can depend on the pres-ence of its parasites. They may not follow the free species, or alternatively they maybecome more virulent when on native hosts, acting as a sort of biological weapon.

This reasoning can be turned on its head in order to explain the failure of an inva-sion. There is any number of scenarios, the plot can become just about as complex asyou wish, and the outcome will to a large extent be linked to the factors on which thelocal adaptation of hosts and parasites depends. Among these factors, the mostimportant are the characteristics which make up the genetic systems of species,migrations, mutations and the reproductive mode, interacting with the abiotic envi-ronment. Parasites are involved in a large number of interactions. An increase in theirtransmission may, directly or indirectly, increase their pathogenic effects and altercharacteristics connected to the reproduction, survival or even behavior of their hosts.The hosts counter-attack. They initiate mechanisms help avoid parasites, stop infec-tion before it starts, or limit its effects.

COLORATION, A SIGNAL AT THE HEART OF COMPLEX INTERACTIONS.

Using color is one of the ways in which animals communicate. It is acompromise between attracting conspecifics, avoiding predators andhiding from prey. The crab spider imitates the precise color of theflower which it is on so as to camouflage itself. It imitates the colorwithin the range to which its predators and prey are sensitive: birdshave four types of cone (UV, blue, green and red) while insects havethree (UV, blue and green). These visual systems differ considerably,

not only in their range of sensitivity but also in the number of photoreceptors. It is thus unlikelythat the spider imitates the color of the flower accurately.A team from the Ecotrop laboratory used spectroradiometry to measure the colors of a spiderplaced on peppermint flowers and then at the center of a tansy ragwort flower. Results frommodeling show that color mimicry can operate simultaneously in the visual systems of predatorsand prey. For birds, the spiders take on the pink color of mint flowers when seen with their fourcone system. Similarly, on the ragwort, each spider has the individual color of the center of theyellow flower on which it hunts its prey. However, against the background of the outer petals ofthe ragwort, where they dont hunt, the spiders produce a strong color contrast which is easilydetected by birds. To hymenoptera the spiders appear to have the same blue-green color as themint flowers when seen with their three-cone system. To hymenoptera, they accurately mimicthe blue-green color of the center of the ragwort flowers, but stand out against the outer petals.These results show that the crab spiders color mimicry works well for the visual systems ofboth predators and prey.

C

NR

S P

hoto

thq

ue /

Ler

ouge

R

oger

Le

Gue

n

Tetrapod fossils from the Devonian. Skullsof Ichtyostega and Acanthostega, and a leg ofTulerpeton compsognathus.

M

NH

M, P

alo

ntol

ogie

, D.S

erre

tte

A PROCESS WHICH UNFOLDS THROUGH TIME

The number of plant or animal species in any particular place not only depends onthe ecological conditions prevailing today but is also the result of history, back to thedistant geological past. Evolution has shaped the structure and functioning of livingcommunities. For example, the extraordinary evolutionary process which during theDevonian, 370 million years ago, led to the appearance of the tetrapods and to verte-brates leaving the water for the first time, had momentous consequences for the his-tory of terrestrial biodiversity. At the other end of the geological time scale, theadaptive radiation i.e. rapid diversification and adaptation of rodents during thePliocene and Quaternary (2 million to 50 000 years ago) enriched terrestrial ecosys-tems with thousands of new species of small size, thus presenting a large number ofcarnivores with renewed biomass.

HUMANS AND BIODIVERSITY

The latest episodes in the history of biodiversity are closely connected to the his-tory of humans. Remains from archaeological sites, of both plants (charcoal, charredseeds, and fruit) and animals (shells and bones), contain a wealth of informationwhich throws light on interactions between human groups and biodiversity. They tellus about both the ways in which humans exploited these raw materials that were nec-essary for their survival and the impact of this exploitation on vegetation cover, thestructure of forests, the composition of animal communities, and the extinction oflarge predators. Seen this way, the archaeological record gives us a unique opportu-nity to observe the long-term effects of a wide range of human activities, whether itbe hunting, fishing or the gathering of shells by small prehistoric groups, the organ-ized management of the countryside by ancient or medieval cities, and animal hus-bandry and farming in the first village societies. Understanding this interaction on thescale of centuries or millennia represents a major contribution to the understandingof biodiversity dynamics, which is of key importance to the management of our cur-rent resources with a view to sustainable development.

16-17

UNDERSTANDINGBIODIVERSITY

These small pierced shells, Nassariuskraussianus, dating from 75 000 years ago,were discovered in the Blombos caves inSouth Africa. They were used as ornaments.They are the oldest jewellery ever discovered.

UNDERSTANDING BIODIVERSITY

Coordinator: Robert BarbaultInstitut fdratif dcologie fondamentale etapplique,(Federal Institut of Fundamental andApplied Ecology) CNRS/universit Paris6,7,12/ENS Cachan/Musum national dhistoirenaturelle (MNHN)/Institut de recherche pour ledveloppement (IRD)With contributions from: Philippe BouchetTaxonomy/Collections Unit, CNRS/MNHN Guillaume LecointreTaxonomy, Adaptation and Evolution Unit,CNRS/Universit Paris 6/MNHN/IRD/ENS Paris

Simon TillierTaxonomy, Adaptation and Evolution Unit,CNRS/Universit Paris 6/MNHN/IRD/ENS Paris Isabelle OlivieriInstitut des sciences de lvolution (Institute ofEvolutionary Sciences), CNRS/UniversitMontpellier 2 Michel VeuillePopulation Genomics Unit, CNRS/colepratique des hautes tudes (EPHE) Anne-Gile AtlanEcosystems, Biodiversity and Evolution (Ecobio)Unit, CNRS/Universit Rennes 1

Ioannis MichalakisGenetics and Evolution of Infectious DiseasesUnit, CNRS/IRD Jean-Denis VigneArcheozoology and History of Societies Unit,CNRS/MNHN Marc ThryFunctioning, Evolution and RegulatoryMechanisms of Tropical Forest Ecosystems Unit(Ecotrop), CNRS/MNHN

C

NR

S P

hoto

thq

ue /

F.d

Err

ico,

M.V

anha

eren

ECOSYSTEMS AND THEIR DYNAMICS

Ecosystems are both physical and biological systems. They are capable of self-regulation and are dependent just as much on the laws of thermodynamics as on thelaws of Darwinian evolution. An ecosystem may be analyzed in terms of its structure.

In this case, researchers study the type of species present, the spatial distributionof its species and physical components, and the organization of food webs betweenspecies. However, the description of these systems can also focus on their function-

ing. In this case, stress is placed on vari-ation in structure over time, themovement of matter and energy withinthe ecosystem, and exchanges of matterand energy with the atmosphere, hydros-phere and geosphere.

Today, ecosystems are subject toconsiderable pressure. They are beingsubjected to rapid climate change, thespread of built-up areas and farmland,and reduction in biodiversity. And yetthey are essential sources of energy,materials and food for humans. Theyplay a key role in regulating biogeo-chemical cycles. Because of this, moreand more research work is being carriedout on them, especially at CNRS.

BIODIVERSITY PRESERVES ECOSYSTEMS

The rapid fall in the number of species present on the planet leads many people towonder about the importance of the role that biodiversity plays in ecosystem dynamics.What effect will reduced biodiversity have on the performance of ecosystems withrespect to resource utilization? Subject to disturbances of various kinds, e.g. storms,fires and pollution, can ecosystems persist? Under what conditions do they maintaintheir capacity for resilience? There is a positive connection between the performance of an ecosystem and the number of species which inhabit it its species diversity

18ECOSYSTEM DYNAMICS

AN ECOSYSTEM IS ONE OF THE MOST COMPLEX ENTITIESRESEARCHERS CAN STUDY. ECOSYSTEMS ARE MORE THAN JUST THETOTALITY OF SPECIES PRESENT IN A GIVEN PLACE. THEY ARE ALSOMADE UP OF ALL THE INTERACTIONS WHICH EXIST BETWEEN THESPECIES AS WELL AS BETWEEN THEM AND THEIR PHYSICAL ENVI-RONMENT. THIS PARTICULARLY DENSE NETWORK OF INTERCON-NECTED RELATIONSHIPS MAKES IT VERY DIFFICULT TO FORECASTECOSYSTEM DYNAMICS.

Development of satellite towns in Brazil.Nothing remains of the original savannahvegetation: only the gallery forests have beenpartly preserved.

C

NR

S P

hoto

thq

ue /

Her

v T

hery

especially in plant communities. For instance, this is the case for European grassland,where, for a given density, plant productivity increases in line with the number of speciespresent. A certain number of observations also hint at genetic diversity having a majorpositive effect on the productivity and stability of ecosystems.

BIOLOGICAL INSURANCE

Biodiversity provides the ecosystem with buffering capacity against fluctuations inthe physical and biological environment. The mechanisms of this effect, known as bio-logical insurance, are still being debated, and are the subject of a great deal of exper-imental and theoretical work within the CNRS. The aim of this research is todetermine to what extent the haphazard selection of particular species, the comple-mentarity between species and the establishment of mutualistic relationshipsbetween species can explain the positive effects of biodiversity on the performanceand resilience of ecosystems. A major research effort is also being carried out on thefunctional significance of the biodiversity of micro-organisms, especially with respectto the regulation of certain key phases in the nitrogen cycle (nitrification and denitri-fication), and more generally on interactions between soil biodiversity and soils phys-ical and chemical characteristics.

PREDICTING THE FUTURE OF ECOSYSTEMS

Diminishing biodiversity leads not only to a reduction in the number of species, butalso to a modification in the structure and dynamics of animal, plant and microbialcommunities. The mechanisms which regulate the size of populations as well as thenature and intensity of interactions between species are thus altered. Predicting theeffects of these changes on the functioning of ecosystems is still not easy to do andgives rise to a great deal of modeling and experimental work. For instance, we are try-ing to understand the role evolutionary mechanisms play in the response of ecosys-tems to climatic variation, predict to what extent the flow of matter and energy can varywithin the ecosystem and between the ecosystem and atmosphere or hydrosphere, anddetermine the conditions that make an organism become an invasive species, and theeffects of invasions on ecosystems. Invasive species themselves are a cause of reducedbiodiversity. For example, there is the famous case of Cape ivy (South Africa), which hasinvaded the whole of Europe and is causing a drastic reduction in the number of plantspecies found in grassland. Climate change and fragmentation of environments alsodisturb communities, and their effects are added to those of species loss. One of thebig challenges for research today is to define the future geographical ranges of speciesby analyzing the characteristics of their life histories, and use them to infer the new(emergent) communities and ecosystems that will form. For instance, depending on

18-19

ECOSYSTEM DYNAMICS

C

NR

S P

hoto

thq

ue /

Xav

ier

Lero

ux

C

NR

S P

hoto

thq

ue /

Ala

in D

ejea

n

Grasshopper trapped by ants. TheseAllomerus decemarticulatus ants, which liveexclusively in the plant Hirtella physophora,construct a trap to capture insects which arethen consumed. The association between thisant and the plant is a mutualism: the plantprovides the ants with a home in the form ofpockets located at the base of the leaves,while in return the ants protect their hostplant against herbivorous insects. Thanks tothis trap, the ants manage to catch insectsover 1,500 times their own weight.

Annual brush fires are a major factor in thedynamics of the West African savannah.

which assumptions are made, by 2100, the beech tree may either completely disappearfrom France or remain just in the western part of the country.

IDENTIFYING THE BIODIVERSITY OF SOILS

The characterization of biodiversity is a difficult stage in any study of the biologicalfunctioning of ecosystems. Indeed, it is practically impossible at species level forthe micro-organisms in soils, fresh water and oceans. New tools are beingdeveloped at CNRS for the rapid characterization of genetic diversity in suchenvironments and to enable comparative approaches to be made. High throughputgenomic techniques as well as DNA chips open up interesting new possibilities forunderstanding how soil biodiversity varies under the influence of environmentalchange, including pollution.DNA chips make it possible to identify micro-organisms present in complex

environments (soils, aquatic environments, etc.). DNA sequences from different micro-organisms areobtained from international data bases. Thanks to the development of new algorithms, researchers atthe Protist Biology Laboratory can then determine the oligonucleotides which are specific to eachspecies of micro-organism, and fix them on a glass slide. The RNA of the micro-organisms from soilsor aquatic environments are then marked with a fluorescent label and hybridized with the specificsequences fixed on the slide. Each dot of light thus reveals the presence in these complexenvironments of one species of micro-organism, and in this way makes it possible to get a betterunderstanding of the mechanisms which govern how these ecosystems work.

quip

e de

Gn

omiq

ue In

tgr

e d

es In

tera

ctio

ns M

icro

bien

nes

The changing distribution of a species ofNorth American tree, Fraxinus americana, overthe 21st century, according to simulationsusing the Phenofit model.Left: simulation of the current range of thespecies using data from the ClimaticResearch Unit (CRU), (University of EastAnglia, UK).Right: simulation of the range of the speciesin 2100 using data from the HadCM3 model

(Hadley Center, UK), according to the A2 model(defined by the IPCC).

The simulation shows that the speciesdispersion ability will not enable it to occupy allthe areas which are climatically favorable in2100, and that populations located at thesouthern most fringe of the range are likely tobecome extinct by 2100.

X

avie

r M

orin

, CEF

E

h

ttp/

/dav

esga

rden

.com

Favorable area not reached

Colonized area

Increased likelihood of occurrence

Decreased likelihood of occurrence

Extinction

Scenario A2 HadCM 32001-2100

CRU TS 2,01901-2000

Simulated probability of occurrence

0 1

Current distribution

THE ECOSYSTEM: A SET OF TROPHIC INTERACTIONS

The concept of biodiversity has revitalized research on ecosystems by focusingattention on interactions between organisms and geochemical cycles. In particular,the aquatic environment has been the subject of a great deal of study in this area, dueto the ease of experimental work within it. CNRS is carrying out a great deal ofresearch in this field. Scientists are attempting to understand the role of the organi-zation of food webs, which are groups of species linked together by predator-preyrelationships. For instance, they determine the trophic connections between speciesand the role of their functional diversity on energy flows and on the movement of themain elements (nitrogen, phosphorus, carbon, etc.) within ecosystems. In addition thecoupling together of classic (plant-animal) food webs and decomposers via the micro-bial loop is more fully integrated. The movement of matter within food webs, or thetrophic level of organisms can be measured more accurately by using markers fororganic matter such as fatty acids or stable isotopes.

...AND NON-TROPHIC INTERACTIONS

Increasing attention is now being paid to allelopathic interactions, in other wordsto the inhibiting or stimulating effects of one species on another via chemical com-pounds. Similarly, the effects of anthropogenic chemical substances cannot be fullyunderstood without taking into consideration the structure of the food webs into whichthey are released. Theoretical and experimental approaches are being developed inorder to better assess the relative proportion of direct or indirect effects of suchchemical substances on the working of ecosystems in connection with the structure

C

NR

S P

hoto

thq

ue /

Nat

halie

Man

sion

C

NR

S P

hoto

thq

ue /

Ala

in P

asqu

et

20-21

ECOSYSTEM DYNAMICS

Left: Nitrogen-fixing nodule (symbiosisbetween Medicago truncatula (alfalfa) andSinorhizobium meliloti).Right: The spider Arycope bruennichi. A largespecies found locally. The blue patches aremarks made by the experimenter in order tomonitor the movement of individual spiders.This makes it possible to test in the field theinfluence of factors such as the density ofprey or of conspecifics on the way in which anindividual changes the place where it makesits web.

RESEARCH ON A LARGE SCALE

In order to understand the consequences of global change in climate or land use on populationsand communities of vertebrates, it is necessary to do research on a large scale. The CNRS Center forBiological Studies at Chiz is carrying out interdisciplinary research on environmental constraints,adaptation of individuals and the implications for managing populations. The goal of this research is toidentify the mechanisms involved, through long-term research on populations of predators andherbivores, both in marine and terrestrial environments. An evolutionary ecophysiological approachmakes it possible to study the mechanistic connections between variation in the environment andphenotypes. Some research has shown the importance of variation in resources over space and timefor the structure of communities. Other studies endeavor to describe the relationships between globalchange and biodiversity conservation. This work mainly concerns threatened species, such as bustardsand albatross, or invasive species such as roe deer, whose dynamics depend very strongly on global

change. These three areas of research are improving our knowledge of populationdynamics and animal communities in a changing environment, and are making itpossible to draw up new principles for the sustainable management of biologicalresources.

C

NR

S P

hoto

thq

ue /

Ric

hard

Lam

oure

ux

The long-tailed nightjar, Caprimulgusclimacurus, is a tropical African migrant and aregular winter visitor. It lives in humanenvironments, such as trails, villages andslash-and-burn cultivation, in the Makokouregion of Gabon.

C

NR

S P

hoto

thq

ue /

Ala

in R

.Dev

ez

of food webs. All these different aspects show how diverse the networks of interac-tions within ecosystems are. A detailed understanding of the role biodiversity plays infunctional processes within ecosystems is no longer conceivable today without takinginto account coupling between networks of trophic and non-trophic interactions (par-asitism, competition, allelopathy and mutualism).

URBAN ECOSYSTEMS

Long considered to be of minor interest, biodiversity in urban environments istoday the subject of several research programs at CNRS. Contrary to popular belief,urban areas are home to a substantial number of species, and some taxa are actual-ly better represented in cities than in the surrounding countryside. Urban biodiversityforms an ideal model for study of many current issues in ecology. This is because thecolonization of these new environments, which on the face of it are not very favorableto living organisms, provides researchers with novel assemblages of species, i.e. withnew models for the analysis of the factors influencing the structure of communities.The extreme fragmentation of urban environments leads to the formation of a networkof habitats that are isolated from each other, and that can also be used in order toidentify processes of colonization and extinction of small populations functioning as anetwork (the metapopulation concept). In addition, cities provide a new type of habitatfor species, which are obliged to adapt to it. It thus forms an authentic evolutionarylaboratory, where we can expect to observe alterations in biological traits (dispersion,reproduction, behavior, etc.) in response to natural selection. Finally, since cities areartificial spaces, they make it possible to study the role of humans in the functioningof ecological systems and to improve the scientific foundations of biodiversity conser-vation in anthropentric environments.

AN OCEANOGRAPHIC LABORATORY FOR THE STUDY OF BIODIVERSITY IN THE MEDITERRANEAN

Oceanographic laboratories have long practiced the interdisciplinary research required for anintegrated approach to ecology and marine biodiversity. They provide facilities for experimental workboth in situ and in the laboratory using naturally circulating seawater, which makes it easier to allowfor interactions between the physical factors of the medium and biological complexity. Theselaboratories have now been established for over a century and a half, and possess series of high-quality long-term observations which not only make it possible to estimate environmental change butalso to validate models. Oceanographic laboratories also play an active role in disseminatingknowledge to decision-makers, schools, clubs and associations, and the general public, thus making acontribution to good governance of the environment. The Diversity, Evolution and Marine FunctionalEcology Unit (Dimar), based at the Endoume oceanographic laboratory, in Marseille, is part of theCentre docanologie de Marseille (Marseille Oceanology Center). It brings together the skills needed

for research into the connections between biological diversity (genetic,phenotypic, specific and functional) and the dynamics and functioning ofmarine ecosystems. Special importance is given to the study of theimpact of large rivers such as the Rhne on benthic communities andon fishing, as well as to biological invasions, since the MediterraneanSea is severely affected by this phenomenon. The results are helping usto understand and predict the impact of disturbances (whether naturalor anthropogenic) and of climate change on coastal environments. Manyresearchers at Dimar are involved as experts in a large number ofprotection and conservation programs, not only locally, but also atregional, national and European levels.

Reef slope in the Cassis area, withParazoanthus (orange sea anemone) andCorallium rubrum (red coral).

C

NR

S P

hoto

thq

ue /

Jea

n-G

eorg

es H

arm

elin

22-23

ECOSYSTEM DYNAMICS

ECOTRONS: ECOSYSTEMS UNDER OBSERVATION

As a result of an article by Michel Loreau published at the end of 1998 in "Bio", the journal of theDepartment of Life Sciences, CNRS decided to equip itself with Ecotrons on a national scale. In theseexperimental stations, natural or artificial ecosystems, as well as animal, plant or microbialcommunities, can be subjected to predetermined environmental conditions. The aim is to understandand predict their responses to pressure such as global climate change.The first Ecotron saw the day in the UK, at the Centre for Population Biology (Imperial College) nearLondon. Its goal is to quantify the relationship between the organization of biodiversity and ecosystemfunctioning. Currently there are two projects under development in France, while a third one isplanned.The first French project is the Montpellier Ecotron, to be located on the CNRS and Baillarguetcampuses. It is planned to contain an experimental plot and an array of twelve macrocosms, which willbe enclosed chambers in daylight, within which the climate can be controlled. The chambers will beequipped with instruments which continuously measure temperature, humidity, the atmospheric CO2concentration, etc. One of their original features is that the chambers will be able to accommodateintact soil monoliths measuring 5 m3 complete with their natural vegetation. An array of mesocosmsand microcosms will used for short-term studies, i.e. less than two years in length. This setup, whichis used to study terrestrial ecosystems, will be completed by the Medimeer station (Ste), where it isalready possible to confine pelagic communities.The Foljuif Ecotron, located near Fontainebleau, is run by the cole normale suprieure. One plot isused to carry out long-term experiments under natural conditions. The core of the project is an arrayof 24 climate chambers designed to subject artificial, terrestrial or aquatic communities andecosystems to a range of environments. Ponds will be used for long-term monitoring of interactions

between the structure of food webs, thedynamics of plankton communities and thephysical chemistry of water. Population cagesare used to test the effect of climate changeand fragmentation of the environment on thedispersion of animals.Finally, sophisticated greenhouses are used toanalyze the functioning of plant communitiesunder semi-controlled conditions.A third Ecotron, given over to Alpinebiodiversity, is under study. It will be set up onthe site of the Lautaret Alpine garden, located

at 2,100 meters altitude. It willin particular include coldgreenhouses which allowaccurate control of soilparameters.

ECOSYSTEM DYNAMICS

Coordinator: Luc AbbadieUnit for Biogeochemistry and Ecology ofContinental Environments,CNRS/Inra/universit Paris 6/Institut nationalagronomique Paris-Grignon (INA-PG)/ ENSParis/cole nationale suprieure de chimie deParis (ENSCP)With contributions from: Gilles BoeufEvolutionary and Cell Biology Models Unit,CNRS/universit Paris 6 Patrick DuncanCentre dtudes biologiques de Chiz (ChizCenter for Biological Studies), CNRS

Pierre-Olivier CheptouCentre dcologie fonctionnelle et volutive(Center for Evolutionary and FunctionalEcology), CNRS/universits Montpellier 1, 2,3/cole nationale suprieure agronomique deMontpellier/Centre de cooprationinternationale en recherche agronomique pourle dveloppement (Cirad) Jean-Pierre FralDiversity, Evolution and Marine FunctionalEcology Unit, CNRS/Universit Aix-Marseille 2 Grard LacroixBiogeochemistry and Ecology of TerrestrialEnvironments Unit, CNRS/Inra/Universit Paris6/INA-PG/ENS Paris/ENSCP

Architects drawing of the Ecotron in Montpellier.

M

anda

tair

e: P

.Alb

aret

- B

ET T

echn

ique

Auv

erte

ch -

Arc

hite

cte

: Age

nce

Mat

te/D

evau

x/R

ouss

eau

F

olju

if

These experimental plots run by CNRSat Foljuif enable researchers to carry outa long-term study of the impact ofclimate warming on the functioning ofpopulations.

24THE IMPACT ON HEALTH

2.5 BILLION IN 1955, OVER 6.5 BILLION TODAY, AND NEARLY 10 BILLIONIN 50 YEARS TIME. THATS THE RATE HOMO SAPIENS SAPIENS ISEXPANDING WITHIN THE BIOSPHERE. HUMANS ARE CHANGING THEEARTH AND ALL ITS ECOSYSTEMS BY UPSETTING THE BALANCE OFINTERACTIONS, COMPETITION AND COOPERATION AMONG SPECIES.WHAT WILL BE THE CONSEQUENCES OF REDUCED BIODIVERSITY FORTHE EVOLUTION OF MICROBES, WHICH, LIKE US, ARE PART OF THELIVING WORLD? OUR HEALTH DEPENDS ON THE ANSWER TO THISQUESTION.

MICRO-ORGANISMS: A CENTRAL ROLE IN THE DEVELOPMENT OF HUMAN POPULATIONS

Micro-organisms are one of the essential biological components of our planet, andone that cannot be ignored. The emergence of higher organisms, including the firsthumans, and their impact on the environment encouraged selection for new types ofactivity by micro-organisms. These new possibilities gave rise to a large number ofassociations which have proved beneficial to humans. Such microbial diversity has agreat impact on human health and on the development of human populations.

EVER SINCE THE BEGINNING OF HUMAN EXISTENCE

Certain micro-organisms colonize humans and live in close interaction with them.They are found on the skin, and in all the human bodys entry and elimination routes:the nasal cavity, the oral cavity, the alimentary tract, etc. These micro-organisms usethe products of the human body or ingested and digested food in order to grow. Thecolonization of these routes by the micro-organisms has been going on, generationafter generation, for at least several thousand years, and possibly for the last 195 000years on the basis of the most recent dating of the oldest skulls of Homo sapiens.However, it has only been in the last fifty years or so that the benefits for human healthof colonization by some of these micro-organisms have been recorded and recog-nized. Some micro-organisms break down food which has not been digested byhumans. They improve digestion, stimulate the immune system, and prevent coloniza-tion by pathogens. These observations have given rise to the term "probiotic", whichdenotes a micro-organism which benefits the health of its