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Spatial mosaic evolution of snail defensive traits
Steven G Johnson1, C Darrin Hulsey, Francisco J García de León
1Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA. sgjohnso@uno.edu
BMC Evolutionary Biology
|April 3, 2007
Summary
Reciprocal selection drives snail defenses, with crushing resistance and shell pigmentation varying with resource productivity and predator frequency. These traits are higher in resource-rich habitats, indicating local adaptation in prey defenses.
Area of Science:
- Ecology
- Evolutionary Biology
- Behavioral Ecology
Background:
- Reciprocal selection models predict escalating coevolution in high-resource environments.
- The study focuses on the freshwater snail (Mexipyrgus churinceanus) and cichlid (Herichthys minckleyi) interaction.
- Investigates spatial variation in snail defensive traits and their relation to environmental factors.
Purpose of the Study:
- Examine spatial variation in snail crushing resistance and shell pigmentation.
- Determine associations between abiotic factors, predator frequency, and snail defensive traits.
- Assess the role of primary productivity in driving small-scale variation in prey defenses.
Main Methods:
- Spatial autocorrelation analysis to account for genetic and geographic divergence.
- Correlation analysis between abiotic variables (temperature, conductivity) and snail traits.
- Investigated relationships between molariform cichlid frequency and snail defensive traits.
Main Results:
- No spatial autocorrelation found for defensive traits at small geographic/genetic distances.
- Abiotic variables showed no correlation with snail defensive traits.
- Crushing resistance and pigmentation negatively correlated with molariform frequency; higher in macrophyte habitats.
Conclusions:
- Snail defenses (crushing resistance, pigmentation) vary significantly at small spatial scales.
- Variation is linked to primary productivity, substrate color, and predator frequency.
- Local adaptation in prey defenses may result from resource productivity interacting with predation pressure.
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