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

Biodiversity can be boosted by colonization of new habitats, such as
different continents and remote islands. 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 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.