Mitochondrial selection and evolutionary insights into nectarivory in Glossophaginae (New world leaf-nosed bats)

The family Phyllostomidae, encompassing a wide range of feeding strategies, is one of the most ecologically diverse groups of bats in the Americas. Within this family, nectarivorous bats of the subfamily Glossophaginae play a significant ecological role as pollinators. This study investigated the mitochondrial genome evolution of species in the Glossophaginae subfamily, focusing on selective pressures acting on their mitochondrial protein-coding genes (PCGs) compared with those of closely related frugivorous and insectivorous species in the family Phyllostomidae.

We sequenced the complete mitochondrial genomes of Glossophaga morenoi and Glossophaga mutica, revealing typical features such as AT-rich nucleotide composition and conserved gene order. Phylogenetic analyses based on PCGs confirmed the relationships of G. morenoi and G. mutica within the genus Glossophaga. We analyzed signals of selective pressures across mitochondrial PCGs using Ka/Ks (ω) values among species in the genus Glossophaga. Ka/Ks (ω) values were consistently < 1 across all studied genes, suggesting that signals of purifying selection act in the mitochondrial genome. Moreover, with RELAX analysis, we found signals of a shift in selection pressures in ATP8, COX1, CYTB, and ND5 PCGs of the subfamily Glossophaginae in comparison to those of Stenodermatinae (frugivorous) and Lonchorhininae (insectivorous) bats. Additionally, MEME selection analysis of these four genes, with a focus on the subfamily Glossophaginae, revealed signatures of positive selection in individual sites of PCGs, which could be associated with adaptations to their nectarivorous diet.

We found conserved mitogenomes in the genus Glossophaga, yet our results reveal significant signatures of selection that may reflect adaptations to the metabolic demands of a nectarivorous lifestyle in Glossophaginae bats.