| Summary: | <p>Abstract</p> <p>Background</p> <p>The Old World warbler genus <it>Sylvia </it>has been used extensively as a model system in a variety of ecological, genetic, and morphological studies. The genus is comprised of about 25 species, and 70% of these species have distributions at or near the Mediterranean Sea. This distribution pattern suggests a possible role for the Messinian Salinity Crisis (from 5.96-5.33 Ma) as a driving force in lineage diversification. Other species distributions suggest that Late Miocene to Pliocene Afro-tropical forest dynamics have also been important in the evolution of <it>Sylvia </it>lineages. Using a molecular phylogenetic hypothesis and other methods, we seek to develop a biogeographic hypothesis for <it>Sylvia </it>and to explicitly assess the roles of these climate-driven events.</p> <p>Results</p> <p>We present the first strongly supported molecular phylogeny for <it>Sylvia</it>. With one exception, species fall into one of three strongly supported clades: one small clade of species distributed mainly in Africa and Europe, one large clade of species distributed mainly in Africa and Asia, and another large clade with primarily a circum-Mediterranean distribution. Asia is reconstructed as the ancestral area for <it>Sylvia</it>. Long-distance migration is reconstructed as the ancestral character state for the genus, and sedentary behavior subsequently evolved seven times.</p> <p>Conclusion</p> <p>Molecular clock calibration suggests that <it>Sylvia </it>arose in the early Miocene and diverged into three main clades by 12.6 Ma. Divergence estimates indicate that the Messinian Salinity Crisis had a minor impact on <it>Sylvia</it>. Instead, over-water dispersals, repeated loss of long-distance migration, and palaeo-climatic events in Africa played primary roles in <it>Sylvia </it>divergence and distribution.</p>
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