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Evolution of physiological tolerance and performance during freshwater invasions
Carol Eunmi Lee1, Jane Louise Remfert, Gregory William Gelembiuk
1Department of Zoology, 430 Lincoln Drive, University of Wisconsin, Madison, Wisconsin 53706.
Integrative and Comparative Biology
|June 18, 2011
Summary
The invasive copepod Eurytemora affinis evolved freshwater tolerance, showing trade-offs between low and high salinity survival. This evolution primarily impacted early life stages, demonstrating natural selection
Area of Science:
- Evolutionary Biology
- Ecology
- Genetics
Background:
- Invasive species often face novel environmental conditions, driving rapid adaptation.
- Eurytemora affinis, typically found in saline environments, has invaded freshwater habitats.
Purpose of the Study:
- To investigate evolutionary changes in salinity tolerance and performance in Eurytemora affinis following freshwater invasion.
- To identify trade-offs and the life stages most affected by salinity selection.
Main Methods:
- Common-garden experiments comparing freshwater (Lake Michigan) and ancestral saline (St. Lawrence marsh) populations.
- Assessed adult survival and developmental survival/timing across a range of salinities (0-25 PSU).
Main Results:
- Freshwater populations showed increased low-salinity tolerance and decreased high-salinity tolerance, indicating evolutionary trade-offs.
- Selection primarily acted on pre-metamorphic stages, with distinct developmental patterns observed across salinities.
- Genetic variation for salinity tolerance was evident, with significant genotype-by-salinity interactions.
Conclusions:
- Natural selection drives rapid evolutionary shifts in reaction norms during aquatic invasions.
- Adaptation to freshwater involves trade-offs and differential selection across life-history stages.
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