Systematics of the New World bats Eptesicus and Histiotus suggest trans-marine dispersal followed by Neotropical cryptic diversification

Abstract

Biodiversity can be boosted by colonization of new habitats such as remote islands and separated continents. Molecular studies have suggested that recently evolved organisms probably colonized already separated continents by dispersal, either via land bridge connections or crossing the ocean. Here we test the on-land and trans-marine dispersal hypotheses by evaluating possibilities of colonization routes over the Bering land bridge and across the Atlantic Ocean in the cosmopolitan bat genus Eptesicus (Chiroptera, Vespertilionidae). Previous molecular studies have found New World Eptesicus more closely related to Histiotus, a Neotropical endemic lineage with enlarged ears, than to Old World Eptesicus. However, phylogenetic relationships within the New World group remained unresolved and their evolutionary history was unclear. Here we studied the systematics of New World Eptesicus and Histiotus using extensive taxonomic and geographic sampling, and genomic data from thousands of ultra-conserved elements (UCEs). We estimated phylogenetic trees using concatenation and multispecies coalescent. All analyses supported four major New World clades and a novel topology where E. fuscus and Histiotus are sister clades that together diverged from two sister clades of Neotropical Eptesicus. Intra-clade divergence suggested cryptic diversity that has been concealed by morphological features, especially in the Neotropics where taxonomic re-evaluations are warranted. Molecular dating estimated that Old World and New World clades diverged around 17 million years ago followed by radiation of major New World clades in the mid-Miocene, when climatic changes might have facilitated global dispersal and radiation events. Biogeographic ancestral reconstruction supported the Neotropical origin of the New World clades, suggesting a trans-Atlantic colonization route from North Africa to the northern Neotropics. We highlight that trans-marine dispersal may be more prevalent than currently acknowledged and may be an important first step to global biodiversification.

Keywords: Biogeography; Colonization; Phylogenetics; Phylogeny; UCE; Ultra-conserved elements.