Hitching a lift on the road to speciation

摘要: Understanding how speciation can take place in the presence of homogenizing gene flow remains a major challenge evolutionary biology. In early stages ecological speciation, reproductive isolation between populations occupying different habitats is expected to be concentrated around genes for local adaptation. These genomic regions will show high divergence while exchange other genome should continue relatively unimpaired, resulting low levels differentiation. The problem explain progresses from this point towards complete isolation, allowing genome-wide divergence. A new study by Via and West (2008) on host races pea aphid, Acyrthosiphon pisum, introduces mechanism ‘divergence hitchhiking’ which generate large ‘islands differentiation’ facilitate build-up linkage disequilibrium, favouring increased isolation. This idea potentially removes stumbling block under continuous flow.