Multi-Locus Phylogeographic and Population Genetic Analysis of Anolis carolinensis: Historical Demography of a Genomic Model Species

The green anole (Anolis carolinensis) has been widely used as an animal model in physiology and neurobiology but has recently emerged as an important genomic model. The recent sequencing of its genome has shed new light on the evolution of vertebrate genomes and on the process that govern species diversification. Surprisingly, the patterns of genetic diversity within natural populations of this widespread and abundant North American lizard remain relatively unknown. In the present study, we use 10 novel nuclear DNA sequence loci (N = 62 to 152) and one mitochondrial locus (N = 226) to delimit green anole populations and infer their historical demography. We uncovered four evolutionarily distinct and geographically restricted lineages of green anoles using phylogenetics, Bayesian clustering, and genetic distance methods. Molecular dating indicates that these lineages last shared a common ancestor ∼2 million years ago. Summary statistics and analysis of the frequency distributions of DNA polymorphisms strongly suggest range-wide expansions in population size. Using Bayesian Skyline Plots, we inferred the timing of population size expansions, which differ across lineages, and found evidence for a relatively recent and rapid westward expansion of green anoles across the Gulf Coastal Plain during the mid-Pleistocene. One surprising result is that the distribution of genetic diversity is not consistent with a latitudinal shift caused by climatic oscillations as is observed for many co-distributed taxa. This suggests that the most recent Pleistocene glacial cycles had a limited impact on the geographic distribution of the green anole at the northern limits of its range

Geographic variation in aggressive signalling behaviour of the Jacky dragon

Signal diversification is often the product of sexual and/or natural selection and may be accompanied by genetic differentiation or simply reflect a plastic response to social and environmental variables.We use an agamid lizard endemic to Australia, the Jacky dragon (Amphibolurus muricatus), to examine the relationships between population relatedness, morphology and signalling behaviour. We also tested whether males are able to discriminate among rivals from different populations and whether they respond more aggressively to more closely related populations. We studied three populations, two of which belong to the same genetic clade. Individuals from the two most closely related populations were also more similar in morphology than lizards from the third, more distant, population. However, all three populations differed in characteristics of their signalling behaviour including latency to display and the interval between displays. In addition, animals from all populations showed similar levels of aggression when matched with individuals from the same or different populations in staged trials and thus did not show evidence of population-level discrimination. We argue that display variation might be a consequence of behavioural plasticity and that, despite difference in genetic structure, morphology and behaviour, this species retains a cohesive communication system.Macquarie UniversityUniversidad de Costa RicaConsejo Nacional para Investigaciones Científicas y Tecnológicas de Costa Rica/FI-252-11/CONYCIT/Costa RicaUCR::Sedes Regionales::Sede del Carib