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Genetic diversity of Diporeia in the Great Lakes: comparison of Lake Superior to the other Great Lakes
Citation:
PILGRIM, E., J. V. SCHAROLD, J. DARLING, AND J. R. KELLY. Genetic diversity of Diporeia in the Great Lakes: comparison of Lake Superior to the other Great Lakes. Presented at International Association of Great Lakes Research , Toronto, ON, CANADA, May 17 - 21, 2010.
Impact/Purpose:
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:
Abundances of Diporeia have dropped drastically in the Great Lakes, except in Lake Superior, where data suggest that population counts actually have risen. Various ecological, environmental, or geographic hypotheses have been proposed to explain the greater abundance of Lake Superior Diporeia. None of these hypotheses, however, have included the possibility of multiple distinct evolutionary lineages of Diporeia in the Great Lakes. Using mitochondrial DNA (ctyochrome oxidase I) sequence data, we compared populations of Diporeia from Lakes Huron, Michigan, Ontario, and Superior. Analyses of this sequence data show Lake Superior Diporeia are a distinct evolutionary lineage that likely diverged over 100,000 years ago from Diporeia of the other Great Lakes. Although these results alone likely are not sufficient to explain the disparity in Diporeia abundance between Lake Superior and the other lakes, the presence of distinct evolutionary lineages of Diporeia within the Great Lakes should be addressed in subsequent investigations of the different population densities of this amphipod.