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Crater lake cichlids individually specialize along the benthic-limnetic axis
Henrik Kusche1, Hans Recknagel2, Kathryn Rebecca Elmer2
1Department of Biology, Chair of Zoology and Evolutionary Biology, University of Konstanz Konstanz, 78457, Germany ; International Max Planck Research School for Organismal Biology, University of Konstanz Konstanz, 78457, Germany.
Ecology and Evolution
|April 29, 2014
Summary
Individual specialization in Midas cichlid fishes (Amphilophus tolteca) occurs along the benthic-limnetic axis. This suggests early ecological divergence within a young species, preceding genetic differentiation.
Area of Science:
- Evolutionary biology
- Ecology
- Ichthyology
Background:
- Adaptive diversification in freshwater fish often involves the evolution of limnetic (open water) and benthic (shore) species from generalist ancestors.
- Individual specialization in phenotype and diet is hypothesized to be an early stage in ecological and evolutionary divergence, facilitating niche partitioning.
Purpose of the Study:
- To investigate individual variation in morphology and diet along the benthic-limnetic axis in the young Midas cichlid species, Amphilophus tolteca.
- To determine if individual specialization occurs in this species and if it correlates with ecological niche use.
- To assess the genetic differentiation within the species in the crater lake environment.
Main Methods:
- Analysis of morphological traits (body shape, pharyngeal jaw morphology) and diet in Amphilophus tolteca.
- Correlation of phenotypic variation with ecological niche.
- Microsatellite genotyping at 13 loci to assess genetic differentiation within the crater lake population.
Main Results:
- Amphilophus tolteca exhibited continuous variation in ecologically relevant traits, including body shape and jaw morphology.
- Phenotypic variation correlated with niche use, indicating individual specialization along the benthic-limnetic axis.
- No significant genetic differentiation was detected among individuals within the crater lake population.
Conclusions:
- Individual specialization in morphology and diet occurs along the benthic-limnetic axis in this young crater lake cichlid species.
- This individual specialization encompasses both limnetic and benthic macro-habitats.
- The absence of genetic differentiation suggests that Amphilophus tolteca is a candidate system for studying the initial stages of sympatric divergence preceding speciation.
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