Ecology Splits Genomes

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Science  29 Jun 2012:
Vol. 336, Issue 6089, pp. 1621
DOI: 10.1126/science.336.6089.1621-a

Evolutionary biologists wish to know how the environment and specialization of a species factor into the process of speciation. Nosil et al. present single-nucleotide polymorphism (SNP) data from eight populations of stick insects (Timema cristinae) that use two different plant species as their hosts, show slight phenotypic differences, and are in the process of speciation. Using a Bayesian model to estimate the differences between the expected and observed allele frequencies and to perform pairwise comparisons among the populations, the authors executed a genome-wide assessment of the genomic signatures related to the host-specific divergence and other ecological and evolutionary factors. As expected, the authors observed an excess of highly divergent polymorphisms between population pairs experiencing mating isolation. Isolation by distance, however, and a correlation between allele frequencies and climatic variables appear to also influence the genomic variation between populations. Thus, these analyses suggest that multiple ecological and evolutionary factors affect the speciation process, and it cannot be explained solely by the shift in plant host use.

Proc. R. Soc. London. Ser. B 279, 10.1098/rspb.2012.0813 (2012).

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