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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Fish Ecology
DISPERSAL PATTERNS OF INVASIVE VS. NONINVASIVE GAMBUSIA: IS THERE A DIFFERENCE?
J.S. Rehage1, R. Holliday1, and A. Sih2. 1Department of Biological Sciences, University of Kentucky, Lexington, KY 40506, 2Department of Environmental Science and Policy, University of California, Davis, CA 95616
A central question in the study of biological invasions is: Do successful invaders have certain attributes in common that contribute to their success? Studying closely related and morphologically similar taxa should allow us to identify these key traits. A good system is the poeciliid fish Gambusia, where the differences in geographic range and invasive ability are extreme. Differences in dispersal rates might be key in explaining the success of invasive Gambusia. We compared the dispersal tendency and ability of the widespread and invasive G. affinis and G. holbrooki and two restricted and noninvasive species, G. geiseri and G. hispaniolae, in two experiments conducted in an artificial arena of tanks connected by shallow channels. In the first experiment, individual gravid females were released at one end of the array and their dispersal quantified by noting the furthest point reached. In a second experiment, we tested the dispersal behavior of Gambusia in social groups, and in the presence and absence of a dispersal barrier (flow, 98 mm sec-1). Groups were placed in the middle pool and allowed to disperse either upstream or downstream. Surprisingly, Gambusia species did not differ in their dispersal tendency or in their ability to cope with low-moderate flow.
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