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Nonindigenous vs. native species: A comparison of preferred niche breadth
Citation:
FRAZIER, M. R., D. REUSSER, AND H. LEE, II. Nonindigenous vs. native species: A comparison of preferred niche breadth. Presented at Marine Bioinvasions Conference, Portland, OR, August 24 - 27, 2009.
Impact/Purpose:
To successfully invade and expand their populations, nonindigenous species must be able to physiologically cope with their new environment.
Description:
To successfully invade and expand their populations, nonindigenous species must be able to physiologically cope with their new environment. Given this, species that tolerate a wide array of environmental conditions are often predicted to be better at establishing populations in new environments. To test this, we compared the preferred niche breadths of nonindigenous and native soft-bottom benthic species for the following variables: temperature, water depth, salinity, dissolved oxygen, pH, latitude, and percent fines (silt plus clay). We predicted that nonindigenous species would have wider preferred niche breadths than native species. Preferred niche breadth was operationally defined as the range of environmental conditions in which a species was observed (presence/absence data) after eliminating the upper and lower 10% of observations. Classification of native and nonindigenous species was based on the “Pacific Coast Ecosystem Information System” (PCEIS) database. The database used to calculate niche breadths included benthic samples collected from Puget Sound in northern Washington to northern Mexico (N > 4,300). Only species that were collected in > 20 benthic grabs were included in the analysis, which reduced the potential species pool to 579 native species and 43 nonindigenous species. To standardize for differences in sample size, we randomly subsampled each species to 20 grabs. Nonindigenous species had a wider thermal tolerance than native species (P = 0.026, N= 329 natives and 34 nonindigenous) but did not otherwise differ from native species. We are currently exploring whether our results are robust to different definitions of niche breadth. Our results suggest that species with wider thermal tolerances have a higher potential for invading the Northeast Pacific and may provide some insight into why the western sides of oceans appear to be dominant donor regions to the Northeast Pacific. Species invading the Northeast Pacific from the Northwest Atlantic (east coast of United States) and Northwest Pacific (Asia) have presumably evolved to survive greater extremes of temperature within their home range, and are therefore well adapted to establish themselves in the Northeast Pacific ecoregions which have milder temperature extremes.