Diversity and dispersal history of the talitrids (Crustacea: Amphipoda: Talitridae) of Bermuda

ABSTRACT

Five taxa of talitrid amphipods were found in the archipelago of Bermuda, of which three were recorded there for the first time. Four of these are supralittoral wrack generalists: Platorchestia monodi BOLD:AAB3402, (a unique Molecular Operational Taxonomic Unit according to the Barcode Index Number system), a related species recognized by molecular methods, Platorchestia platensis BOLD:AAA2949, Mexorchestia carpenteri carpenteri BOLD:AAC1491 and Tethorchestia antillensis; and one a terrestrial leaf-litter generalist: Talitroides alluaudi. A key is provided to discriminate between the formally described talitrids of Bermuda. Dispersal mechanisms from the American continent to Bermuda were considered for all taxa based on species distributions along the North American Atlantic coast and also investigated by molecular methods, using genetic population differentiation and haplotype network analysis based on the barcode region of cytochrome c oxidase subunit I gene. For P. monodi BOLD:AAB3402 the genetic results suggest that some dispersal events occurred before human colonization of Bermuda but are equivocal about the source population and therefore the direction of dispersal. Some very recent synanthropic dispersal is possible with this species. For the other two species studied genetically, P. platensis BOLD:AAA2949 and M. c. carpenteri BOLD:AAC1491, the small population samples analysed support dispersal to Bermuda from the American mainland, before human occupation of Bermuda, although the available sample size was limited for these species. The available limited direct, non-genetic evidence supports synanthropic transport for Talitroides alluaudi. Platorchestia monodi BOLD:AAB3402 is found in the same wrack habitat as P. platensis BOLD:AAA2949 on Bermuda, apparently without interbreeding. No evidence was found that driftwood specialist talitrids had become established in Bermuda.

KEYWORDS:

• Dispersal
• biodiversity
• oceanic island
• cytochrome c oxidase subunit I
• DNA barcoding

Acknowledgements

We thank Dr T. Trott for facilitating export of the samples to Canada for further study, Mr Blythe Chang for drawing Figure 1 and Ms Mandy Shailer for drawing Figure 2. We also thank the staff of the Canadian Centre for DNA Barcoding at the Biodiversity Institute of Ontario, University of Guelph, for conducting the molecular laboratory analyses. Additional support for the DNA sequencing was provided by Genome Canada in support of the International Barcode of Life project. We also acknowledge the Ontario Ministry of Research Innovation for providing funding to Paul Hebert for the development of BOLD, which was important for data management and analysis for this project. Thanks to Dr Martin Thiel for reviewing the manuscript. This is Contribution #236, Bermuda Biodiversity Project (BBP), Bermuda Aquarium, Natural History Museum and Zoo, Department of Conservation Services.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The molecular component of this research was funded by an NSERC Discovery Grant to SJA [grant number 386591-2010] and by a graduate scholarship from CONACYT to TLQ [grant number 315757].