Molecular phylogeny of the Indian Ocean Terpsiphone paradise flycatchers: Undetected evolutionary diversity revealed amongst island populations

2013
We construct a molecular phylogeny of Terpsiphone flycatchersof the Indian Ocean and use this to investigate their evolutionary relationships. A total of 4.4 kb of mitochondrial (cyt-b, ND3, ND2, control region) and nuclear (G3PDH, MC1R) sequence data were obtained from all species, sub-species and island populations of the region. Colonisationof the western Indian Ocean has been within the last two million years and greatly postdates the formation of the older islands of the region. A minimum of two independent continent-island colonisationevents must have taken place in order to explain the current distribution and phylogeneticplacement of Terpsiphone in this region. While five well-diverged Indian Ocean clades are detected, the relationship between them is unclear. Short intermodal branches are indicative of rapid range expansion across the region, masking exact routes and chronology of colonisation. The Indian Ocean Terpsiphone taxa fall into five well supported clades, two of which (the Seychelles paradise flycatcherand the Mascarene paradise flycatcher) correspond with currently recognised species, whilst a further three (within the Madagascar paradise flycatcher) are not entirely predicted by taxonomy, and are neither consistent with distance-based nor island age-based models of colonisation. We identify the four non-Mascarene clades as Evolutionarily Significant Units (ESUs), while the Mascarene paradise flycatchercontains two ESUs corresponding to the Mauritius and Reunion subspecies. All six ESUs are sufficiently diverged to be worthy of management as if they were separate species. This phylogeneticreconstruction highlights the importance of sub-specific molecular phylogeneticreconstructions in complex island archipelago settings in clarifying phylogenetichistory and ESUs that may otherwise be overlooked and inadvertently lost. Our phylogeneticreconstruction has identified hidden pockets of evolutionary distinctiveness, which provide a valuable platform upon which to re-evaluate investment of conservation resources within the Terpsiphone flycatchersof the Indian Ocean.
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