Unraveling the Myotis Morass: Ultraconserved-Element Analysis Reveals Introgression, Cryptic Diversity, and Taxonomic Trouble in the Most Species-rich Bat Genus

Using sequences from 2615 UCE loci and multiple methodologies we inferred phylogenies for the largest genetic dataset of New World Myotis to date. The resulting phylogenetic trees were populated with short branch lengths and widespread conflict, hallmarks consistent with rapid adaptive radiations. The degree of conflict observed in Myotis has likely contributed to difficulties disentangling deeper evolutionary relationships. Unlike earlier phylogenies based on 1-2 gene sequences, this UCE dataset places M. brandtii outside the New World clades. Introgression testing of a small subset of our samples revealed evidence of historical but not contemporary gene flow, suggesting that hybridization occurs less frequently in the Neotropics than the Nearctic. We identified several instances of cryptic lineages within described species as well as several instances of potential taxonomic over-splitting. Evidence from Central and South American localities suggests that diversity in those regions is not fully characterized. In light of the accumulated evidence of the evolutionary complexity in Myotis and our survey of the taxonomic implications from our phylogenies it is apparent that the definition of species and regime of species delimitation need to be re-evaluated for Myotis . This will require substantial collaboration and sample sharing between geneticists and taxonomists to build a system that is both robust and applicable in a genus as diverse as Myotis . ### Competing Interest Statement The authors have declared no competing interest.