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Incipient speciation across a depth gradient in a scleractinian coral?
1Wrigley Institute for Environmental Studies, University of Southern California, P. O. Box 5069, Avalon, California 90704, USA. dbcarlon@ucdavis.edu
Evolution; International Journal of Organic Evolution
|December 19, 2002
Summary
Marine coral speciation may occur without geographic barriers. Two distinct morphotypes of Favia fragum in Panama show genetic divergence, suggesting early stages of species formation with gene flow.
Area of Science:
- Marine Biology
- Evolutionary Biology
- Genetics
Background:
- Speciation can occur without geographic isolation.
- Marine environments offer unique systems to study divergence.
- Coral reefs face threats, making understanding their evolution crucial.
Purpose of the Study:
- Investigate morphological and genetic divergence in Favia fragum.
- Determine if reduced gene flow maintains distinct morphotypes.
- Explore speciation mechanisms in corals.
Main Methods:
- Multivariate analysis of polyp morphology.
- Allozyme electrophoresis to assess genetic variation.
- Haplotype analysis and population genetics statistics.
Main Results:
- Two distinct Favia fragum morphotypes identified with opposing depth distributions.
- Significant genetic differences (allele and haplotype frequencies) between morphotypes.
- Morphotype explained 35% of genetic variation, indicating divergence with gene flow.
Conclusions:
- Favia fragum morphotypes exhibit divergence potentially leading to speciation.
- Gene flow is reduced between morphotypes, maintaining distinct genetic and morphological traits.
- Reproductive isolation mechanisms may be involved in this divergence-with-gene flow process.