Biological Invasions in Marine Ecosystems

Volume 204 of the series Ecological Studies pp 203-214

Escape from Parasites

  • Mark E. TorchinAffiliated withSmithsonian Tropical Research Institute
  • , Kevin D. LaffertyAffiliated withU.S. Geological Survey, Western Ecological Research Center, Marine Science Institute, University of California

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In betting circles, the odds-on favorite of a sporting match can depend on the health of the star players; a pulled hamstring or bad flu can determine the winner. Introduced species are often in contest with native species and their impacts are directly proportional to their demographic performance in the novel environment. Demographic performance can encompass population level parameters, such as densities, abundances, and biomass as well as individual level parameters, such as growth rate, survivorship and fecundity. One indication of an invader's demographic performance is size because individuals that grow fast or live long can become large. On average, marine invaders attain larger sizes compared to populations in their native range (Grosholz and Ruiz 2003). This increased performance, if it translates into increased standing biomass, should positively correlate with an invader's impact (Crivelli 1983). Exploring reasons for invasion success will not only accelerate our understanding of species interactions, but will strengthen our ability to manage invasions.