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Spatial geographic mosaic in an aquatic predator-prey network.
Johel Chaves-Campos1, Steven G Johnson, C Darrin Hulsey
1Department of Biological Sciences, University of New Orleans, New Orleans, Louisiana, United States of America.
Plos One
|July 30, 2011
Summary
Coevolutionary trait matching varies spatially, influenced by gene flow. Snail shell strength and fish crushing morphotype frequency correlate, indicating local adaptation in predator-prey dynamics.
Area of Science:
- Ecology
- Evolutionary Biology
- Coevolutionary Studies
Background:
- The geographic mosaic theory of coevolution posits that predator-prey interactions vary geographically.
- This variation is driven by spatial differences in traits and influenced by gene flow between populations.
- Understanding these dynamics is crucial for predicting evolutionary trajectories.
Purpose of the Study:
- To investigate spatial variation in snail defensive traits and fish predator morphotypes.
- To examine the role of gene flow in shaping coevolutionary patterns between freshwater snails and fish.
- To test predictions of the geographic mosaic theory in a natural system.
Main Methods:
- Documented spatial variation in crushing resistance of three freshwater snail species (Mexipyrgus churinceanus, Mexithauma quadripaludium, Nymphophilus minckleyi).
- Assessed the relative frequency of the crushing morphotype in the polymorphic fish Herichthys minckleyi across 11 communities.
- Analyzed gene flow patterns in both snails and fish using phylogeographic methods.
Main Results:
- Significant spatial variation was observed in both snail crushing resistance and fish morphotype frequency.
- Snail crushing resistance was not explained by geographic proximity or genetic similarity.
- Limited gene flow was detected in snails, while fish showed more widespread gene flow, suggesting snails drive local divergence.
Conclusions:
- Gene flow in snails contributes to a mosaic of local divergence in shell strength, potentially preventing predator morphotype fixation.
- A negative correlation between fish morphotype frequency and snail shell crushing resistance supports trait matching across the geographic mosaic.
- The findings align with the geographic mosaic theory, highlighting the importance of spatial variation and gene flow in coevolution.
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