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Genetic diversity in two introduced biofouling amphipods (Amphipods valida and Jassa marmorata) along the Pacific North American coast: investigation into molecular identification and cryptic diversity
Citation:
PILGRIM, E. AND J. DARLING. Genetic diversity in two introduced biofouling amphipods (Amphipods valida and Jassa marmorata) along the Pacific North American coast: investigation into molecular identification and cryptic diversity. Diversity and Distributions. Blackwell Publishing Limited, Oxford, Uk, 16:827-839, (2010).
Impact/Purpose:
Non-indigenous aquatic species (NIAS) are widely recognized as a major environmental threat to ecosystems and economies across the United States (US). Continued introduction and spread of NIAS ranks second only to habitat loss in terms of effects on native biodiversity, effects on existing food webs and resulting economic costs. NIAS introductions have been increasing at unprecedented rates over past decades, largely due to modernization and growth of global transport infrastructure and economic trade. Understanding the role played by principle vectors and conditions favoring NIAS spread must become a critical element of any comprehensive plan for environmental protection that ensures the sustainability of endemic ecosystems and the beneficial resources they provide. EERD has initiated a research effort to develop tools to detect morphologically cryptic NIAS, understand transport pathways and secondary spread of invasive species, and assess patterns and environmental influences on hybridization between native and invading taxa. A primary objective of this research is to evaluate the relative contributions of coastal versus long-distance ballast mediated introductions, and to differentiate secondary introductions via ballast transport from post-introduction range expansion.The study includes targeted screening of ballast (from international and coastal traffic) and population genetic surveys for species of concern to determine whether San Francisco Bay is acting as a local source pool for secondary spread (via ship and/or current transport) to other west coast estuaries. Target organisms include Spartina alterniflora,which has disrupted Pacific Coast ecosystem processes and threatens endemic cordgrass species due to competition and hybridization, as well as globally significant invaders such as European green crab (Carcinus maenas) and the Chinese mitten crab (Eriocheir sinensis). In a related study, EERD researchers are assessing the use of DNA identification tools for early detection and monitoring of invasive species in high risk ports across the Great Lakes.
Description:
We investigated patterns of genetic diversity among invasive populations of A. valida and J. marmorata from the Pacific North American coast to assess the accuracy of morphological identification and determine whether or not cryptic diversity and multiple introductions contribute to the contemporary distribution of these species in the region.