title: Bermuda as an evolutionary life raft for an ancient lineage of endangered lizards.
abstract: Oceanic islands are well known for harboring diverse species assemblages and are frequently the basis of research on adaptive radiation and neoendemism. However, a commonly overlooked role of some islands is their function in preserving ancient lineages that have become extinct everywhere else (paleoendemism). The island archipelago of Bermuda is home to a single species of extant terrestrial vertebrate, the endemic skink Plestiodon (formerly Eumeces) longirostris. The presence of this species is surprising because Bermuda is an isolated, relatively young oceanic island approximately 1000 km from the eastern United States. Here, we apply Bayesian phylogenetic analyses using a relaxed molecular clock to demonstrate that the island of Bermuda, although no older than two million years, is home to the only extant representative of one of the earliest mainland North American Plestiodon lineages, which diverged from its closest living relatives 11.5 to 19.8 million years ago. This implies that, within a short geological time frame, mainland North American ancestors of P. longirostris colonized the recently emergent Bermuda and the entire lineage subsequently vanished from the mainland. Thus, our analyses reveal that Bermuda is an example of a "life raft" preserving millions of years of unique evolutionary history, now at the brink of extinction. Threats such as habitat destruction, littering, and non-native species have severely reduced the population size of this highly endangered lizard.
authors.affiliation: Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley, California, United States of America. matthew.brandley@yale.edu
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Brandley
authors.forename: Yuezhao
authors.initials: Y
authors.lastname: Wang
authors.forename: Xianguang
authors.initials: X
authors.lastname: Guo
authors.forename: Adrián
authors.initials: A
authors.lastname: Nieto Montes de Oca
authors.forename: Manuel
authors.initials: M
authors.lastname: Fería Ortíz
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hikida
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Ota
mesh_terms: D000818:Animals; D001605:Bermuda; D005075:Biological Evolution; D008116:Lizards; D010802:Phylogeny