Authors: Erik M Pilgrim Michael J Blum Deborah A Reusser Henry Lee John A Darling
Publish Date: 2013/04/30
Volume: 15, Issue: 11, Pages: 2415-2428
Abstract
Reconstructing the invasion history of aquatic invasive species can enhance understanding of invasion risks by recognizing areas most susceptible to invasion and forecasting future spread based on past patterns of population expansion Here we reconstruct the invasion history of the Japanese amphipod Grandidierella japonica Stephensen 1938 combining information from historical collection data with molecular genetic data to better understand postinvasion range expansion and anthropogenic connectivity across the Pacific coast of North America Compilation of collection data from bays and estuaries of the Pacific North American coast show many new localities have been colonized in the last two decades moving outward from harbors and bays with high commercial traffic into smaller coastal locations dominated by local recreational traffic DNA barcode sequence data for G japonica reveals two distinct clades one found in San Francisco Bay and sites to the north and one also found in San Francisco Bay and sites to the south The two clades differ by an average 728 genetic distance large enough to consider these invasive amphipods two separate species Both northern and southern clades exhibit low levels of genetic diversity suggesting a single introduction event for each The presence of cryptic diversity within this invasive amphipod highlights the need for more extensive study of the invasive and native populations of aquatic invasive invertebrates to address questions of taxonomy diversity and invasion historyWe would like to thank Dr Bruce Boese Dr John Chapman and Janet Lamberson for their insightful comments on an earlier manuscript and for collecting amphipods in Yaquina Bay Oregon We also would like to thank Jack Kelly Florence Fulk Mark Bagley and two anonymous reviewers for their comments on this manuscript The views expressed in this manuscript are those of the authors and do not necessarily reflect the views or policies of the US Environmental Protection Agency or the US Geological Survey
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