Conflicting mitochondrial and nuclear paraphyly in small-sized West African house bats (Vespertilionidae)
Abstract
Hybridization between species may result in introgression of mitochondrial DNA from one species to another. Phylogenetic inference, therefore, may not recover true evolutionary relationships.
In bats, there are only a few reported cases of introgressive hybridization. House bats are a genus with obscure phylogeny and taxonomy, caused mainly by morphological similarity.
We undertook a detailed analysis of small-sized West African house bats (Scotophilus), tentatively identified as S. nigritellus, to clarify relationships between two sympatric colour forms. These forms were recovered in paraphyletic position to each other in both mitochondrial and nuclear phylogenies, signifying that they are two distinct species.
While the yellow-bellied form could be assigned beyond doubt to S. nigritellus s. str., the white-bellied form may be an as yet undescribed species. Moreover, the white-bellied form clustered as a sister mitochondrial lineage to another species, Scotophilus leucogaster.
These sister lineages differed by only 2.6-2.8% sequence divergence, which lies within the intraspecific range for this genus. Two nuclear markers, however, contradicted the sister relationship, showing them instead to be distantly related.
The apparent conflict between the mitochondrial and nuclear signals suggests that past hybridization may have occurred between these morphologically distinct species.