DNA barcodes to study and marine biological invasions

1. DNA 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.

2. Marine Biological Invasions Introduced species Exotic species Nonindigenous species Alien species Marine species established with human assistance outside their native ranges.

3. Invaders cause ecological and economic harm Caulerpa taxifolia Carcinus maenas Potamocorbula amurensis Eriocheir sinensis Asterias amurensis

4. Invasions are increasing in frequency Marine invertebrate invasions in North American waters Number of first reports N=298 Ruiz et al. 2000

5. The major modern culprit: ballast water

6. 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?

7. 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 crypticspecies complexes confuse patterns of invasion III. Issues of taxonomy: the “simple” problem of identification of adults • Taxonomic expertise is scarce and overburdened. • Ecologists and managers lack data.

8. Without solving these problems, pressing research is hindered Mechanisms and pathways of invasion Primary sources Secondary spread Propagule pressure Native regions Stepping stones Community and population dynamics Relation between diversity, disturbance, prior invasion history and vulnerability. Management practices and assessments Evaluating ballast water management practices; e.g., ballast water exchange. Early detection and eradication “This looks new? Is it invasive? What should I do?”

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

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

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

12. 2001 * * * * * * * * *

13. Target species or genera Macoma (multiple species) Mytilus galloprovincialis Protothaca staminea Tivela stultorum

14. Mytilus galloprovincialis Mytilus californianus Macoma nasuta Protothaca staminea Tresus nuttalli Cytochrome b sequences discriminate species and contain regions that can be used to design species-specific primers. 1400 PCR products scored after gel electrophoresis.

15. 2001 2000 Low tide High tide High tide Low tide Average of available replicates *incomplete * * * * * *sand 25-90% of larvae/sample were from an introduced mussel. .

16. II. Systematic and biogeographic problems Cryptogenic species (modified from Cohen and Carlton 1995): Species which cannot be reliably identified as native or introduced, frequently considered “cosmopolitan.”

17. California Department of Fish and Game 2002. Introduced Aquatic Species in California Final Report. 7-20% Cryptogenic species

18. DNA data can solve the problem of cryptogenic species Cosmopolitan species could be: A single species, truly cosmopolitan. A single species spread by human mediated transport. 3) Multiple species erroneously described as a single species. Combinations of 2&3 Each scenario has a predicted genetic prediction (gene flow, founder effects, phylogenetic structure)

19. Ophiactis savignyi: a pantropical species? "most common brittlestar in the world" -Clark 1946 in Roy and Sponer 2002.

20. Pacific haplotypes found in the Western Atlantic; Indo-west Pacific Closure of Isthmus of Panama Eastern Pacific Western Atlantic 500 bp mt-CO1

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

22. “Mytilus edulis”: once considered cosmopolitan. Genetic data shows multiple, geographically separated species Invasion of California was unnoticed because a native sibling species was already there.

23. Next, decline of native mussel was unnoticed because it was replaced. Geller, J.B. 1999. • 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 North South Braby and Somero 2006

24. Carcinus maenas 1817 1980 1989 1900 1983 Sibling species also mask multiple invasions 16S mt-rRNA Geller et al. 1997

25. Geller et al. 1997

26. ~30% California Department of Fish and Game 2002. Introduced Aquatic Species in California Final Report. IV. Taxonomic issues: the “simple” job of Identifying adults.

27. Who is going to identify the samples? Polychaeta

28. 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.

29. Taxonomic expertise is scarce and experts are overburdened. Watersipora sp. Mackie et al. 2005