Abstract
BackgroundEcological release is coupled with adaptive radiation and ecological diversification yet little is known about the molecular basis of phenotypic changes associated with this phenomenon. The venomous, predatory marine gastropod Conus miliaris has undergone ecological release and exhibits increased dietary breadth at Easter Island.Methodology/Principal FindingsWe examined the extent of genetic differentiation of two genes expressed in the venom of C. miliaris among samples from Easter Island, American Samoa and Guam. The population from Easter Island exhibits unique frequencies of alleles that encode distinct peptides at both loci. Levels of divergence at these loci exceed observed levels of divergence observed at a mitochondrial gene region at Easter Island.Conclusions/SignificancePatterns of genetic variation at two genes expressed in the venom of this C. miliaris suggest that selection has operated at these genes and contributed to the divergence of venom composition at Easter Island. These results show that ecological release is associated with strong selection pressures that promote the evolution of new phenotypes.
Highlights
Understanding the origins of biodiversity is a fundamental concern in biology
Recent analyses support the prediction of greater niche variation in generalist populations that have experienced ecological release [5,6,7], with few exceptions [8,9] very little is known about the heritability of this variation or the molecular genetic bases of the evolution of new phenotypes that result
To illuminate the factors that drive the evolution of Conus venoms and the impact of ecological release on venom evolution, we investigated the differentiation of venoms among populations of Conus miliaris, a species that shows evidence of dietary breadth expansion at Easter Island [14]
Summary
Understanding the origins of biodiversity is a fundamental concern in biology. Ecological release, or the increased availability of resources afforded by reduced competition [1], can instigate adaptive radiations and was likely responsible for some of the most dramatic diversifications of life in earth’s history [2,3]. We examined patterns of variation at two conotoxin loci among populations from Easter Island in the southeastern Pacific, Guam in the western Pacific, and American Samoa in the South Pacific and compared these to patterns of variation observed at a region of the mitochondrial cytochrome oxidase I (COI) gene.
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