PARENT SESSION
Symposium 20: Evolution on ecological time scales
Organized by: A Hendry, D Réale, and G Fussmann
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 517 B, Level 5, Palais des congrès de Montréal
Contemporary evolution versus ecology as determinants of population performance in an exotic fish.
Kinnison, Michael*,1, Unwin, Martin2, Quinn, Thomas3, 1 Department of Biological Sciences, Orono, ME, USA2 National Institute of Water and Atmosphere Research, Christchurch, New Zealand3 School of Aquatic and Fishery Sciences, Seattle, WA, USA
ABSTRACT- Though success of exotic species is commonly attributed to ecological factors that influence habitat quality, contemporary evolution is also theoretically favored under the conditions that typify population invasion and establishment. However, reviews of contemporary evolution suggest that associated trait evolution is often modest and capable of being produced by similarly modest intensities of selection. These observations lead to questions about the practical importance of contemporary evolution, versus habitat quality (ecology), in determining the success of exotic populations over short time scales. Here we provide a framework for evaluating the relative importance of contemporary evolution based on evolution of fitness and the extent that it modifies population patterns of lifetime performance expected under habitat quality alone. Lifetime performance metrics (i.e., survival and offspring production) are especially useful as measures of the value of evolution because they integrate fitness effects over much more of the phenotype than individual traits, and they can be related to potential rates of population growth. Using this framework and translocation experiments in the wild, we demonstrate rapid divergence of population performance in exotic populations of a migratory fish (Oncorhynchus tshawytscha). This evolution of fitness occurred in 26 generations (or less) and is proportionately much larger than divergence in any individual characters for these salmon. More importantly, this evolution is estimated to reduce habitat dependent costs on performance by half. Our results thus provide empirical evidence that adaptation plays a major role in the performance of exotic populations. Our results also suggest a basis for evolution of ecologically mediated isolation within the invaded range.
Key words: rapid evolution, evolution of fitness, exotic species, habitat quality