Phylogeographic structure of Tridacna crocea across the

Indo West Pacific

“How diverse is your clam chowda?”

Matthew Subia1, Paul Barber2

1CSU Monterey Bay, 2Boston University

Fish

Corals

Snails

Roberts et al. 2002

IWP is Center of Marine Biodiversity

Giant Clam Distribution

Giant Clam Importance

• Food

• Colorful decorations

• During 1960’s and 70’s annual landings estimated at 100-400 tons.

• In 1985, clams were included in the convention on International Trade in Endangered Species of Wild Fauna and flora

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are needed to see this picture.

Concerns for Giant Clams

• Commercial and artisanal exploitation

• Bleaching

• Disease

• Pollution

• Poaching

Tridacna crocea

Natural History of T. crocea

• Adults tend to burrow in coral in waters less than 10 m deep

• Hermaphroditic and reach sexual maturity in approximately 5-7 years

• Broadcast spawners– Sperm released first– Eggs follow

• Algal symbionts and filter feeders

PacificOcean

IndianOcean Australia

Asia

400km

Coastal marginsduring low sea levelsstands

Indonesia in the Pleistocene

After Voris 2002 400km

Williams et al. 2002

Genetic differentiation of Pacific and Indian Ocean populations of Starfish

Lavery et al. 1996

McMillan & Palumbi 1996Williams & Benzie, Benzie & Williams 1997

Duke et al. 1999

ST=0.87p=0

H. pulchella

Sampled C & W Pacific Populations

Plotted Nm values on geography

Objectives

• What are the patterns of genetic structuring of T. crocea in Indonesia?

• Is there evidence for limited genetic exchange among populations?

• Do they show Pacific-Indian Ocean split?

Methods

• Extracted DNA from T. crocea tissue samples using Chelex

• Amplified DNA using PCR and mtCO1 T. crocea specific primers

• Sequenced DNA using ABI 377

• Sequences aligned and edited using Sequencher 4.5

• Sequences analyzed in Arlequin 2.0

N=287

Geographic Distribution

AMOVA Results

---------------------------------------------------------------------- Source of Sum of Variance Percentage variation d.f. squares components of variation ------------------------------------------------- --------------------- Among groups 5 955.468 3.70605 Va 39.60 Among populations within groups 12 233.243 0.97774 Vb 10.45 Within populations 269 1257.522 4.67480 Vc 49.95 ---------------------------------------------------------------------- Total 286 2446.233 9.35859 ---------------------------------------------------------------------- Fixation Indices FST : 0.50048 ---------------------------------------------------------------------- P(rand. value <= obs. value) = 0.00000+ - 0.00000

Pairwise Comparison

------------------------ Population pairwise FSTs ------------------------ Papua 1 Papua 2 E. Indo N. Indo S. Indo Aceh Papua 1 0.00000 Papua 2 0.54912 0.00000 E. Indo 0.28892 0.18212 0.00000 N. Indo 0.52310 0.03873 0.09190 0.00000 S. Indo 0.60368 0.03403 0.23377 0.05885 0.00000 Aceh 0.68351 0.67235 0.42528 0.56291 0.69159 0.00000

Conclusion

• T. crocea demonstrates a new pattern in comparison to previously studied species in this region

• Three distinct clades exist:– 1 in the far west– 1 in the far east– 1 in central

• Therefore, T. crocea shows regional genetic structure

Acknowledgements

• Paul Barber

• Elizabeth Jones

• Joshua Drew

• Eric Crandall

• Timery DeBoer

• Craig Starger

• NSF