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Ecological opportunity and sexual selection together predict adaptive radiation
Catherine E Wagner1, Luke J Harmon, Ole Seehausen
1Department of Fish Ecology & Evolution, EAWAG Centre for Ecology, Evolution and Biogeochemistry, 6047 Kastanienbaum, Switzerland. catherine.wagner@eawag.ch
Nature
|June 23, 2012
Summary
Adaptive radiation in cichlid fishes is driven by ecological opportunity and sexual selection. These factors, combined with lake depth, solar radiation, and time, predict diversification, not just lake size.
Area of Science:
- Evolutionary Biology
- Ecology
- Ichthyology
Background:
- Understanding biodiversity requires explaining why some species groups undergo adaptive radiations while others do not.
- Extrinsic environmental factors and intrinsic lineage-specific traits influence species diversification.
- African Great Lakes cichlid fishes offer dramatic examples of species diversification, yet most lineages haven't radiated adaptively.
Purpose of the Study:
- To investigate the factors driving adaptive radiation in cichlid fishes across 46 African lakes.
- To determine the interaction between environmental features and lineage-specific traits in promoting or inhibiting adaptive radiation.
- To identify predictors of adaptive radiation in cichlid fish lineages.
Main Methods:
- Compiled data on cichlid colonization and diversification in 46 African lakes.
- Collected data on lake environmental features (depth, solar radiation, surface area, time).
- Analyzed traits of colonizing cichlid lineages, focusing on sexual dichromatism as a proxy for sexual selection intensity.
Main Results:
- Ecological opportunity (deep lakes, high solar radiation, longer diversification time) and sexual selection (indicated by sexual dichromatism) strongly predict cichlid adaptive radiation.
- Lake surface area showed weak or negative associations with diversification, unlike terrestrial taxa.
- The coincidence of ecological opportunity and sexual selection is the key predictor for cichlid adaptive radiation.
Conclusions:
- Adaptive radiation in cichlids is predictable when ecological opportunity and species traits, particularly sexual selection, are jointly considered.
- Environmental factors like lake depth and solar radiation, alongside intrinsic traits, are crucial for understanding diversification patterns.
- This study highlights the importance of integrating extrinsic and intrinsic factors to explain the evolutionary success of species radiations.
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