A new giant anole (Squamata: Iguanidae: Dactyloinae) from southwestern Ecuador

We describe a new species of Anolis lizard from the Pacific slopes of the Andes of southwestern Ecuador at elevations between 372–1,000 m. The new species belongs to the Dactyloa clade and may be distinguished from other Anolis by size, external anatomy, mitochondrial DNA divergence, and dewlap color. Based on phylogenetic analyses of mitochondrial and nuclear DNA sequence data, we found that the new species is sister to A. fraseri in a clade composed primarily of large Dactyloid species. The new species is known from a protected area in southern Ecuador, Buenaventura Reserve, which suggests that at least some its populations are well protected.

Lampreys, the jawless vertebrates, contain three Pax6 genes with distinct expression in eye, brain and pancreas

The transcription factor Pax6 is crucial for the development of the central nervous system, eye, olfactory system and pancreas, and is implicated in human disease. While a single Pax6 gene exists in human and chicken, Pax6 occurs as a gene family in other vertebrates, with two members in elephant shark, Xenopus tropicalis and Anolis lizard and three members in teleost fish such as stickleback and medaka. However, the complement of Pax6 genes in jawless vertebrates (cyclostomes), the sister group of jawed vertebrates (gnathostomes), is unknown. Using a combination of BAC sequencing and genome analysis, we discovered three Pax6 genes in lampreys. Unlike the paired-less Pax6 present in some gnathostomes, all three lamprey Pax6 have a highly conserved full-length paired domain. All three Pax6 genes are expressed in the eye and brain, with variable expression in other tissues. Notably, lamprey Pax6α transcripts are found in the pancreas, a vertebrate-specific organ, indicating the involvement of Pax6 in development of the pancreas in the vertebrate ancestor. Multi-species sequence comparisons revealed only a single conserved non-coding element, in the lamprey Pax6β locus, with similarity to the PAX6 neuroretina enhancer. Using a transgenic zebrafish enhancer assay we demonstrate functional conservation of this element over 500 million years of vertebrate evolution.

Genetic reconstruction of the invasion history of Anolis wattsi in Trinidad with a comment on the importance of ecological similarity to invasion success

Human activities have reshaped patterns of island biogeography for many groups of amphibians and reptiles. In Trinidad, an island in the West Indies with only one native Anolis lizard species, four additional anole species have been introduced since the 1800s. The most recent introduction, Anolis wattsi, native to Antigua, has become established despite the presence of multiple species of resident anoles. We used genetic data (mitochondrial DNA) to infer the geographic origin and genetic structure of introduced A. wattsi on Trinidad. We then gathered published data to compare eco-morphological traits of all anole species currently established on the island. We found three mtDNA haplotypes in Trinidad that clustered with two different clades from the northern part of the native range in Antigua, rejecting the hypothesis that the lizards originated in the pineapple-growing region of the south. However, a lack of fine-scale population structure precluded precise identification of the origin in Antigua of haplotypes introduced to Trinidad. Compared to the other anole species on Trinidad, A. wattsi is smaller, perches lower, and has a higher field body temperature. Thus, the successful establishment and spread of A. wattsi should not be surprising given the success of two previous introductions of anole species that were more similar ecomorphologically to the native species and each other, and the fact that Trinidad has relatively few anole species for its size.

A new cryptic species of Anolis lizard from northwestern South America (Iguanidae, Dactyloinae)

A new species ofAnolislizard from the Andean slopes of southwestern Colombia and northwestern Ecuador, from between 1187 and 2353 m in elevation, is described. The new species can be distinguished from otherAnolisin squamation, cranial osteology, hemipenial morphology, and nuclear and mitochondrial DNA. The new species is sister toAnolisaequatorialis, and it is suggested that previous records ofA.aequatorialisin Colombia correspond to the new species described herein.

Thermal niche evolution across replicated Anolis lizard adaptive radiations

Elucidating how ecological and evolutionary mechanisms interact to produce and maintain biodiversity is a fundamental problem in evolutionary ecology. Here, we focus on how physiological evolution affects performance and species coexistence along the thermal niche axis in replicated radiations of Anolis lizards best known for resource partitioning based on morphological divergence. We find repeated divergence in thermal physiology within these radiations, and that this divergence significantly affects performance within natural thermal environments. Morphologically similar species that co-occur invariably differ in their thermal physiology, providing evidence that physiological divergence facilitates species coexistence within anole communities. Despite repeated divergence, phylogenetic comparative analyses indicate that physiological traits have evolved more slowly than key morphological traits related to the structural niche. Phylogenetic analyses also reveal that physiological divergence is correlated with divergence in broad-scale habitat climatic features commonly used to estimate thermal niche evolution, but that the latter incompletely predicts variation in the former. We provide comprehensive evidence for repeated adaptive evolution of physiological divergence within Anolis adaptive radiations, including the complementary roles of physiological and morphological divergence in promoting community-level diversity. We recommend greater integration of performance-based traits into analyses of climatic niche evolution, as they facilitate a more complete understanding of the phenotypic and ecological consequences of climatic divergence.