Reassessing a Holocene extinction: multiple lines of evidence do not support the historical presence and recent extirpation of a protected anole on the island of Anguilla

Michael L Yuan , Rayna C Bell, Edward A Myers

Accurate assessment of historical species ranges is important for conservation science and management. Inaccurate historical species ranges can lead to incorrect assumptions about local extinctions, population trends, and potential sites for reintroductions. Yet, historical knowledge is often lacking for many species. Here, we examine the case of the bearded anole, Anolis pogus, which is long believed to have been recently extirpated from the island of Anguilla. We addressed the evidence for the historical presence and recent local extinction of A. pogus on Anguilla using species abundance modeling, fossil and extant morphological data, and archival DNA sequencing from museum specimens. We found that although viable habitat remains on Anguilla, it is highly fragmented. Our data is also not consistent with the prior characterization of two size classes of anoles in Anguilla's fossil deposits as evidence for the two species (A. gingivinus and A. pogus) that occur sympatrically on neighboring St. Martin. Instead, our data indicate that fossil deposits on Anguilla likely correspond to males and females of the larger anole species, A. gingivinus, and is not consistent with the presence of A. pogus in the fossil record. Finally, we sequenced the only two known museum specimens of A. pogus from Anguilla and demonstrate that these specimens correspond to A. schwartzi and were likely missorted (and subsequently misidentified) when a collection from Anguilla and St. Eustatius was originally deposited at the Museum of Comparative Zoology. Together, our results show that there is no evidence for the historical presence, and thus no evidence for the local extinction, of A. pogus on Anguilla. These data are vital for the appropriate management of this species of conservation concern. Furthermore, our study provides a case study for the critical assessment of historical species ranges and narratives of extinction.