EVOLUTION, SYSTEMATICS, BIOGEOGRAPHY, AND CONSERVATION OF DIPLOGLOSSID LIZARDS

Abstract

Research on island biodiversity has played an integral part in our understanding of speciation, biogeography, and adaptive radiations. The islands of the Caribbean provide an ideal location to study evolutionary hypotheses because of their proximity to species-rich mainland source areas while being sufficiently isolated to preserve an endemic biota. Most of the more than 1,000 Caribbean reptile and amphibian species occur nowhere else and are typically restricted to a single island. However, anthropogenic pressures resulting in habitat loss and degradation threaten biodiversity, leading to the loss of undescribed and unstudied species. Few studies have been conducted on the phylogenetic relationships and biogeography of Neotropical forest lizards (Diploglossidae) because of the rarity of most species. Before my work, there were 3 recognized genera and 53 species of these lizards, found in Middle America, South America, and on Caribbean islands. I gathered and analyzed sequence DNA of 3,232 genes and 642,775 aligned base pairs in 30 currently recognized diploglossid species and conducted phylogenetic, phylogenomic, biogeographic, ecological, and morphological analyses. I found that Neotropical forest lizards are older and more species-rich than previously thought. Based on this, I described 2 new subfamilies, 4 new genera, and 18 new species. I also resurrected four genera and elevated 17 subspecies to the species level. The family Diploglossidae now contains three subfamilies, 12 genera, and 91 species. I assigned all 59 Caribbean celestine species to IUCN Redlist threat classes, with the primary threats being habitat loss and introduced predators Of these, fifteen species (25%) are Critically Endangered, seventeen species (29%) are Endangered, one species (2%) is Vulnerable, and twenty-six (44%) are Least Concern. Four of the Critically Endangered species are extinct, or possibly extinct. Four of the Critically Endangered species are extinct, or possibly extinct. My biogeographic analyses indicate that forest lizards reached the Caribbean islands by at least two dispersal events, in the Oligocene and Miocene, likely by floating on flotsam from northern South America. Past and present ocean currents facilitated these initial dispersal events and subsequent dispersals among Caribbean islands. Finally, I assigned the species of Neotropical forest lizards to six different ecomorph classes based on ecology, morphology, and statistical analyses. Several of these ecomorphs appear multiple times in my phylogeny, indicating that convergent evolution has occurred within the family.