Verifying invasive marine fish species using molecular techniques: A model example using triplefin fishes (Family Tripterygiidae)

Abstract

Molecular techniques can resolve many questions concerning the identification and origins of invasive marine species. We used a molecular taxonomy based on the mitochondrial control region (mtCR) to identify the origin of three cryptogenic triplefin species (Family: Tripterygiidae) found in two Australian ports—Port Phillip Bay, Melbourne and the Derwent Estuary, Hobart. DNA was extracted from Australian specimens of Forsterygion varium, F. lapillum , and Grahamina gymnota , and PCR (polymerase chain reaction) fragments of the mitochondrial control region (mtCR, c. 400 bp) were amplified, sequenced, and aligned to a reference alignment containing 23 endemic New Zealand triplefin species. Multiple specimens were sequenced for Australian F. varium , and G. gymnota , and the sequences were aligned to data sets from conspecific specimens collected around New Zealand. The sequences from Australian specimens of F. varium and G. gymnota consisted of only one and two haplotypes, respectively. Haplotypes of all three Australian species nested among New Zealand conspecific haplotypes, and the single Australian F. varium haplotype was shared with two southern New Zealand individuals. The low genetic diversity in two of the Australian triplefin populations of F . varium and G. gymnota and their close genetic relationship to New Zealand populations strongly suggests recent introductions from New Zealand to Australia.

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