DNA barcodes to study and marine biological invasionsDNA barcodes to study and marine biological invasions

What are marine invasions?

Why are we interested?

What are the challenges?

How can DNA barcodes help?Examples of applications to invasive species

problems.

What are marine invasions?

Why are we interested?

What are the challenges?

How can DNA barcodes help?Examples of applications to invasive species

problems.

Marine Biological InvasionsMarine Biological Invasions

Introduced species

Exotic species

Nonindigenous species

Alien species

Introduced species

Exotic species

Nonindigenous species

Alien species

Marine species established with human assistance outside their native ranges.

Invaders cause ecological and economic harm

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are needed to see this picture.

Caulerpa taxifolia

Potamocorbula amurensis

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Carcinus maenas

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.Eriocheir sinensis

Asterias amurensis

Invasions are increasing in frequency

Ruiz et al. 2000

Marine invertebrate invasions in North American waters

Num

ber

of f

irst

repo

rts

N=298

The major modern culprit: ballast water

Why study invasions?Why study invasions?

Basic community ecology and evolutionary biology.

Why are some species good invaders but not others?

Why are some communities more vulnerable or resistant?

How do invaders adapt to new enviroments?

How much biogeography is natural or anthropogenic?

Conservation and economics.For policy-makers: risk of harm.

Understand risks of intentional introductions.

How can we best protect native species?

What are effective management practices?

Basic community ecology and evolutionary biology.

Why are some species good invaders but not others?

Why are some communities more vulnerable or resistant?

How do invaders adapt to new enviroments?

How much biogeography is natural or anthropogenic?

Conservation and economics.For policy-makers: risk of harm.

Understand risks of intentional introductions.

How can we best protect native species?

What are effective management practices?

What are some of the problems in studying invasions that DNA barcodes can solve?

I. Issues of identification of larvae and juveniles.• Invaders arrive as larvae.• Invaders spread as larvae.

II. Issues of biogeography and systematics• Many species are cryptogenic: we don’t know if they

are invaders or not. • Sibling and cryptic species complexes confuse patterns

of invasion

III. Issues of taxonomy: the “simple” problem of identification of adults1. Taxonomic expertise is scarce and overburdened.2. Ecologists and managers lack data.

Without solving these problems, pressing research is hindered

Mechanisms and pathways of invasion Primary sources

Secondary spreadPropagule pressure

Native regionsStepping stones

Community and population dynamicsRelation between diversity, disturbance, prior invasion history and vulnerability.

Management practices and assessmentsEvaluating ballast water management practices; e.g., ballast water exchange.

Early detection and eradication“This looks new? Is it invasive? What should I do?”

I. Identifying larvae of invasive species in plankton(natural or ballast water)

Larvae of most marine invertebrates are undescribed. When descriptions are adequate, identification is slow and laborious.

Using DNA barcodes to identify larvae of introduced mussels in Morro Bay, California

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2001

Target species or genera

Tivela stultorum

Macoma (multiple species)

Protothaca stamineaMytilus galloprovincialis

Cytochrome b sequences discriminate species and contain regions that can be used to design species-specific primers.

1400 PCR products scored after gel electrophoresis.

G9FBG19FA

G13MBG20FAG28FAG26FBG27FA

C10MAC22FAC19FBC3MAC26FBC13FA

C21FBC23FA

MNC33BAMN13BMNC39BMN1A

MN17BMN5AMNC42BBMNC34BBMMN6AMNC45BAMNC40BAMMN4AMIC13A

MS1AMS9AMS10B

PS27APSC25B

PSC23ABPSC24ABPSC28BPSC26ABPSC14AA

SGABMercenaria

SG1AATS4A

PitarCalyptogena

ArcticaTNC47BBTNC8BAMTN2BTN3ATN1ATNC6BAMTN1BATNC47BA

SpisulaC.gigas

10 changes

Mytilus galloprovincialis

Mytilus californianus

Macoma nasuta

Protothacastaminea

Tresus nuttalli

Identified Larvae in May

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station/tide

larvae/m^3

Unknown

Protothaca

Tresus

Macoma

Mytilus

incomplete

sand

Ave

rag

e o

f ava

ilab

le r

epl

ica

tes

Low tide Low tideHigh tide High tide

2000 2001

25-90% of larvae/sample were from an introduced mussel..

Cryptogenic species (modified from Cohen and Carlton 1995):

Species which cannot be reliably identified as native or introduced, frequently considered “cosmopolitan.”

II. Systematic and biogeographic problems

California Department of Fish and Game 2002. Introduced Aquatic Species in California Final Report.

Cryptogenic species

7-20%

Cosmopolitan species could be:

1) A single species, truly cosmopolitan.2) A single species spread by human mediated transport.3) Multiple species erroneously described as a single species.4) Combinations of 2&3

Each scenario has a predicted genetic prediction (gene flow, founder effects, phylogenetic structure)

DNA data can solve the problem of cryptogenic species

Ophiactis savignyi: a pantropical species?

"most common brittlestar in the world"-Clark 1946 in Roy and Sponer 2002.

Western Atlantic

Indo-west Pacific

Eastern Pacific

Pacific haplotypes foundin the Western Atlantic;

Closure ofIsthmus of Panama

500 bp mt-CO1

Genetic data shows multiple, geographically disjunct species“Mytilus edulis”: once considered cosmopolitan.

“Mytilus edulis”

Genetic data shows multiple, geographically separated species“Mytilus edulis”: once considered cosmopolitan.

Invasion of California was unnoticed because a native sibling species was already there.

Next, decline of native mussel was unnoticed because it was replaced.Next, decline of native mussel was unnoticed because it was replaced.

DNA from museum collections from the late 1800’s shows M. trossulus in southern CA

M. galloprovincialis arrived in Southern CA in the 1930's

It has progressively spread northward and replaced M. trossulus

DNA from museum collections from the late 1800’s shows M. trossulus in southern CA

M. galloprovincialis arrived in Southern CA in the 1930's

It has progressively spread northward and replaced M. trossulus

Geller, J.B. 1999.

Braby and Somero 2006

North South

19891817

1983 1900

1980

Carcinus maenas

16S mt-rRNA Geller et al. 1997

Sibling species also mask multiple invasions

Geller et al. 1997

Atlantic haplotype (%)

Mediterranean haplotype (%)

Banyul-Sur-Mer, France 0 100

Naples, Italy 0 100

Rio de Betanzos, Spain 100 0

Cadiz, Spain 100 0

Texel Island and Den Helder, Netherlands 100 0

Isle of Wight, U.K. 100 0

Bodega Harbor, CA, USA 100 0

Mystic, CT, USA 100 0

Capetown, South Africa 92 8

Falmouth, Tasmania 100 0

Tokyo Bay, Japan 33 67

California Department of Fish and Game 2002. Introduced Aquatic Species in California Final Report.

IV. Taxonomic issues: the “simple” job ofIdentifying adults.

~30%

Who is going to identify the samples?

Polychaeta

The future of DNA barcoding for the study of marine invasions.

A complete Census of Marine Life/Barcoding project would include all invaders and all potential invaders.

Targeted DNA barcoding of known invaders and high risk species would provide tools now.

DNA barcoding coupled to innovations in sequence detection can speed identification of new invaders, assist monitoring efforts, and relieve taxonomic experts of repetitive identification requests.

Taxonomic expertise is scarce and experts are overburdened.

Watersipora sp.

Mackie et al. 2005