Phylogenetics and phylogeography of the Hipposideros commersoni (Chiroptera) species complex with special reference to Malagasy populations.

Abstract

ABSTRACT Hipposideros commersoni is endemic to Madagascar and is relatively common in the western portion of the island, where it is found in different habitats from sea level to 1325 m. A previous study on patterns of morphological variation within the species highlighted the presence of two distinct morphotypes larger individuals in the north of Madagascar and smaller individuals in the south. Molecular techniques using DNA sequence data in combination with morphology have been previously used to identify cryptic hipposiderid species. This thesis presents the results of analyses based on molecular data and craniodental measurements in H. commersoni occurring on Madagascar, and related African forms. The molecular analyses suggest that H. commersoni with respect to Madagascar is paraphyletic, with strong support for the presence of independently evolving lineages. Two individuals amongst those sequenced from areas in the south of Madagascar represent a unique evolutionary lineage (Clade A), distinct from other H. commersoni, and has been recently named as a new species, H. cryptovalorona. This species is sister to H. gigas and H. vittatus, both restricted to Africa. Within H. commersoni, the molecular data support two geographically distributed clades -- one in the south (Clade B) and the other in the north (Clade C). Morphometric data were consistent with the molecular analyses, suggesting a north–south break within H. commersoni. Bayesian clustering analysis showed that H. commersoni comprised four main lineages: B1, B2, B3 and C. The most recent common ancestor of H. commersoni was dated to 3.33 million years ago or the mid-Pliocene. Population expansion events were inferred for groups B1, B2 and B3 from approximately 127,600 (group B1) to 6,870 years BP (group B2). Conflicting results were obtained from Bayesian clustering and AMOVA analyses; strong population genetic structure was obtained from the former but not the latter. Sequence data indicated that genetic subdivisions failed to support an isolation-by-distance model. Lineage dispersal, genetic divergence and expansion events of H. commersoni are likely to be associated with Plio-Pleistocene climate fluctuations. Our data indicate the northern and the central western regions of Madagascar may have acted as refugia for this species during the Plio-Pleistocene.