Journal Club 25 Sept 2016: Potential merger of ancient lineages in a passerine bird discovered based on evidence from host-specific ectoparasites
The occurrence of deep mtDNA lineages in an otherwise homogenous genome may suggest that populations have been isolated in allopatry for long periods of time, but have more recenly been mixed. Such merger of formerly isolated lineages is hypothesized to occur only under certain conditions. There are not many examples of this phenomenon, but a recent study by Block et al. (2015) is an exception. They show with mtDNA sequencing and microsatellite screening of a Malagasy passerine, Xanthomixis zosterops, may possibly represent a instance of merging of deep lineages. There is also very interesting data of host-specific feather lice in the genus Myrsidea, suggesting three major phylogroups. supporting allopatry in X. zosterops.
The sampling sites, mtDNA lineages of the two main players in the present study: X. zosterops and its associated Myrsidea (Figure 2 in Block et al.).