Divergence times of ecotypes

Range ~150,000 - 700,000 years ago
Organism Killer whale Orcinus orca
Reference Morin PA. et al., Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species. Genome Res. 2010 Jul20(7):908-16. doi: 10.1101/gr.102954.109. abstract, p.912 left column 2nd paragraph & table 2PubMed ID20413674
Method Abstract: "Using killer whales as a case study, [investigators] have developed a method to readily sequence, assemble, and analyze complete mitochondrial genomes from large numbers of samples to more accurately assess phylogeography and estimate divergence times...[They] used high-throughput sequencing to survey whole mitochondrial genome variation of 139 samples from the North Pacific, North Atlantic, and southern oceans."
Comments Abstract: "Phylogenetic analysis indicated that each of the known ecotypes represents a strongly supported clade with divergence times ranging from approximately 150,000 to 700,000 yr ago." P.912 left column 2nd paragraph: "[Investigators'] estimated dates of divergence based on the entire mitogenome are much older than those inferred from short mitochondrial and nuclear loci...Using these inferences as [their] hypotheses, [they] used whole mitogenomes to infer killer whale evolutionary patterns, and [their] results indicate much deeper initial separation (either geographic or ecological) between the mammal-eating Transient clade in the North Pacific and a second clade in the Atlantic or lower latitudes ∼700,000 yr ago, followed by ecological and/or geographical diversification of the second clade into the present day types at high latitudes, including secondary contact with Transients. These splits between types date from ∼150,000–700,000 yr ago rather than 20,000–40,000 yr ago, consistent with species or subspecies level designations."
Entered by Uri M
ID 112711