Species InteractionsSpecies InteractionsHUMANS IN THE BIOSPHEREHUMANS IN THE BIOSPHERE

CHAPTER 6 CHAPTER 6

Biodiversity and Biodiversity and Extinction: The sixth great Extinction: The sixth great

wavewave

ADAPTED FROM BBC ARTICLE by Alex Kirby

All the creatures we share the All the creatures we share the Earth with are important in some Earth with are important in some way, however unprepossessing way, however unprepossessing or insignificant they may appear. or insignificant they may appear. They and we are all part of the They and we are all part of the web of life.web of life.

From the dawn of time, extinction has From the dawn of time, extinction has usually progressed at what scientists usually progressed at what scientists call a natural or background rate. call a natural or background rate. Today the tempo is far faster. Today the tempo is far faster.

Many scientists believe this is Many scientists believe this is the sixth great wave - the sixth the sixth great wave - the sixth mass extinction to affect life on mass extinction to affect life on

Earth. Earth. FIVE MASS EXTINCTIONS Cretaceous (About 65 million years ago) Triassic (About 208 million years ago) Permian (About 245 million years ago) Devonian (About 360 million years ago) Ordovician (About 438 million years ago)

Human Population GrowthHuman Population Growth

We have more than doubled our We have more than doubled our numbers in half a century, and that is numbers in half a century, and that is the most obvious reason why there is the most obvious reason why there is less room for any other species less room for any other species

We are taking their living room to We are taking their living room to grow our food, their food to feed grow our food, their food to feed ourselves. We are exploiting them, ourselves. We are exploiting them, trading in them, squeezing them to trading in them, squeezing them to the margins of existence - and the margins of existence - and beyond. beyond.

LIVING PLANET INDEXLIVING PLANET INDEX

LIVING PLANET INDEX LIVING PLANET INDEX

The index tracks the size of specific The index tracks the size of specific populations of selected speciespopulations of selected species

It shows them as a percentage of the It shows them as a percentage of the 1970 populations1970 populations

It shows falling population levels in It shows falling population levels in all three ecosystem types studiedall three ecosystem types studied

Often the choice is hard: conserve a Often the choice is hard: conserve a species or feed a community, species or feed a community, tourists' dollars or turtles' nests tourists' dollars or turtles' nests

FactsFacts

In 2003 the World Conservation Union's In 2003 the World Conservation Union's Red List said more than 12,000 Red List said more than 12,000 species (out of 40,000 assessed) species (out of 40,000 assessed) faced some extinction risk, including: faced some extinction risk, including:

one bird in eight one bird in eight 13% of the world's flowering plants 13% of the world's flowering plants a quarter of all mammals. a quarter of all mammals.

Why is biodiversity Why is biodiversity important?important?

Many species keep us alive, purifying Many species keep us alive, purifying water, fixing nitrogen, recycling water, fixing nitrogen, recycling nutrients and waste, and pollinating nutrients and waste, and pollinating crops. crops.

Plants and bacteria carry out Plants and bacteria carry out photosynthesis, which produces the photosynthesis, which produces the oxygen we breathe. Trees absorb oxygen we breathe. Trees absorb carbon dioxide, the main greenhouse carbon dioxide, the main greenhouse gas given off by human activities. gas given off by human activities.

Contributions lostContributions lost

Tropical cone snails contain toxins Tropical cone snails contain toxins which show promise for treating some which show promise for treating some forms of cancer and heart irregularities. forms of cancer and heart irregularities. One toxin may be a thousand times One toxin may be a thousand times more potent than morphine for pain more potent than morphine for pain relief. relief.

Millions of cone snails are now killed Millions of cone snails are now killed annually for their shells, and their annually for their shells, and their habitats are under pressure. habitats are under pressure.

Contributions lostContributions lost Brazil nuts are a lucrative Brazil nuts are a lucrative

harvest in the Amazon. But harvest in the Amazon. But an experiment to produce an experiment to produce them in plantations failed, them in plantations failed, because the trees bear a because the trees bear a good crop in the forest, but good crop in the forest, but are barren in isolation. are barren in isolation.

US researchers estimate US researchers estimate that by 2020 less than 5% that by 2020 less than 5% of the Amazon will remain of the Amazon will remain in pristine condition. in pristine condition.

Amazon DeforestationAmazon Deforestationhttp://geography.uoregon.edu/bartlein/animations/rondonia.gif

Animation show 1982 to 1992Animation show 1982 to 1992

Contributions lostContributions lost

Within 15 years, about a fifth of Within 15 years, about a fifth of central Africa's forests will have gone central Africa's forests will have gone

71% of UK butterfly species are 71% of UK butterfly species are reported to be decliningreported to be declining

Humans are bucking the trend Humans are bucking the trend towards extinction. In 1953 there towards extinction. In 1953 there were about 2.5bn people: today were about 2.5bn people: today there are 6bn. there are 6bn.

Population Pressure: HawaiiPopulation Pressure: Hawaii Stressed Stressed

physiologicaphysiological conditions l conditions may may threaten the threaten the health and health and sustainabilitsustainability of coral y of coral reefs reefs

Extinction versus Extinction versus EndangeredEndangered

Extinction is foreverExtinction is forever Endangered = still timeEndangered = still time Biodiversity Video

US Department of Fish and US Department of Fish and Game,Game,

Endangered Species DivisionEndangered Species Division Listing StatusListing Status

EndangeredEndangered Critically EndangeredCritically Endangered ThreatenedThreatened RareRare http://www.fws.gov/endangered/wildlife.

html#Species

Ecological IssuesEcological IssuesWhat do you know about What do you know about

the following?the following?A.A. Global Warming “Greenhouse Effect”Global Warming “Greenhouse Effect”

1.1. Caused byCaused by2.2. _______is trapped between the ____________ and _______is trapped between the ____________ and

the earth.the earth.3.3. Problems?Problems?

B.B. Ozone DepletionOzone Depletion1.1. Caused by the__________________________________________ Caused by the__________________________________________

which remove which remove ____________________________________________________.____________________________________________________.

2.2. Problems?Problems?

C.C. Acid RainAcid Raina)a) Burning _____________________________ produces SOBurning _____________________________ produces SO22 and and

NONOxx

b)b) They mix with water forming They mix with water forming c)c) Problems?Problems?

Ecological IssuesEcological IssuesA.A. Global Warming “Greenhouse Effect”Global Warming “Greenhouse Effect”

1.1. Caused by the accumulation of COCaused by the accumulation of CO2 and CH42 and CH4

2.2. Heat is trapped between the COHeat is trapped between the CO22 layer layer and the earth.and the earth.

3.3. Problems?Problems?

4.4. Solution? Solution? http://www.androidworld.com/prod60.htm

Ecological IssuesEcological Issues

B. Ozone DepletionB. Ozone Depletion1.1. Caused by the CFC’s Caused by the CFC’s

(Chloroflurocarbons) removing ozone (Chloroflurocarbons) removing ozone molecules from the atmosphere.molecules from the atmosphere.

2.2. Problems? – UV light allowed in!Problems? – UV light allowed in!

3.3. CFC’s banned in 1980’s – the result is CFC’s banned in 1980’s – the result is positive as some scientists predict the positive as some scientists predict the holes may shrink and disappear in holes may shrink and disappear in approx. 50 yrsapprox. 50 yrs

Ecological IssuesEcological Issues

C. Acid RainC. Acid Raina)a) Burning fossil fuels produces SOBurning fossil fuels produces SO22 and and

NONOxx

b)b) They mix with water forming They mix with water forming Sulfuric Acid (HSulfuric Acid (H22SOSO44) ) making the making the rain acidic.rain acidic.

c)c) Problems?Problems?

Fish-Eating Birds

Magnification ofDDT Concentration

10,000,000

100,000

10,000

1,000,000

1

1000

LargeFish

Small Fish

Zooplankton

Producers

Water

Section 6-3

Figure 6-16 Biological Magnification of DDT

Biological MagnificationBiological Magnification

Harmful pollutants become more Harmful pollutants become more concentrated as they make there concentrated as they make there way up the food pyramidway up the food pyramid

California connection: mercury California connection: mercury magnificationmagnification

CA history link

SuccessionSuccession

Two TypesTwo Types Primary successionPrimary succession Secondary successionSecondary succession

Primary Succession Primary Succession - begins in barren areas, such as on - begins in barren areas, such as on bare rock exposed by a retreating glacier. The first inhabitants are lichens bare rock exposed by a retreating glacier. The first inhabitants are lichens or plants—those that can survive in such an environment. Over hundreds or plants—those that can survive in such an environment. Over hundreds

of years these “pioneer species” convert the rock into soil that can of years these “pioneer species” convert the rock into soil that can support simple plants such as grasses. These grasses further modify the support simple plants such as grasses. These grasses further modify the

soil, which is then colonized by other types of plants. Each successive soil, which is then colonized by other types of plants. Each successive stage modifies the habitat by altering the amount of shade and the stage modifies the habitat by altering the amount of shade and the

composition of the soil. The final stage of succession is a climax composition of the soil. The final stage of succession is a climax community, which is a very stable stage that can endure for hundreds of community, which is a very stable stage that can endure for hundreds of

years.years.

Secondary successionSecondary succession