Gleaning, Trawling, And Aerial Hawking: Distinct Genes With Similar Functions Underlie Convergent Evolution In Myotis Bats

Adaptive radiations represent the response of successful lineages in the face of ecological opportunity. By diversifying in their morphology and behavior, daughter lineages can exploit new and different resources, thereby avoiding competitive exclusion. The mouse-eared vesper bats Myotis offer an instructive example. With 139 species, Myotis is the second-most species-rich genus of mammal, and six of Illinois’ 13 species of bats belong to this genus, including the little brown bat. Myotis is cosmopolitan in distribution, found on all continents save Antarctica. Its global success has been fostered through the adoption of three very different foraging modes that allow them to access highly differentiated resources: gleaning, trawling, and aerial hawking. Each mode is characterized by different sets of phenotypic features that have evolved multiple times in the evolution of this genus. In the new study, the team examined the genomes of 30 bat species, looking for evidence of selection in a sample that included 21 species of Myotis with gleaners, trawlers and hawkers each from multiple continents. They screened 16,426 genes for positive selection and associations between relative evolutionary rates and foraging strategies. The colonization of new environments may have required changes in genes linked to hearing sensory perception, fecundity and development, metabolism of carbohydrates, and heme degradation. These changes apparently reflect the needs of prey acquisition and digestion. The repeated evolution of bat ecomorphs does not always involve changes in the same genes but rather in genes with the same molecular functions.
September 6. 2024