Adaptive innovation after colonization of novel thermal environments:
The green anole, Anolis carolinensis provides an intriguing example of natural invasion. A. carolinensis is nested within the Cuban green anole clade, dispersing overwater to the establish in peninsular Florida as late as the Pliocene. The only anole native to the continental United States, A. carolinensis has spread from Florida throughout the southeast to occupy a range of environments as far north as Tennessee, North Carolina and Oklahoma. It is hypothesized that winter temperatures limit the northern edge of the species’ distribution. However, despite regular ambient temperatures below freezing, northern populations of this species endure winter by retreating to sheltered sites and basking on rock faces during periods of sun exposure. I use this species as a model to understand how changes in environment influence evolution and shape the process of adaptation at niche, phenotypic and genomic level.
Rapid evolutionary response to extreme weather events:
Polar Vortex-mediate winter storm that swept through the green anole range during the winter of 2013-2014
Catastrophic weather events have long been considered strong agents of natural selection, dating back as early as Bumpus’ study (1899) of selection and mortality in house sparrows in response to a winter storm. However, the effects of extreme weather events remain surprisingly understudied. Global climate change is expected to increase the frequency and intensity of extreme weather events. Therefore, measuring organismal response to such events has become increasingly important for estimating the rate of survival and the pace of adaptive response in natural populations. Using multiyear physiological and genomic datasets, I am currently investigating signatures of winter storm-mediated selection in the green anole and (in collaboration with Jason Kolbe at University of Rhode Island) a recent invasive species, the brown anole Anolis sagrei.
You can find a short presentation about part of this research below:
Physiological and regulatory adaptation to urban heat islands:
Urbanization creates local environments that are hotter than surroundings natural areas and has widespread biological consequences. As a result urban areas serve as excellent natural experiments to investigate the impact of human-mediated climate change on evolution and adaptation. As human populations expand globally, these insights will be necessary to gain a clearer picture of how adaptation and acclimation allow species to persist in the face of increased human alterations across the planet. In collaboration with Kristin Winchell, I am studying the effects of urban heat islands on physiological and regulatory divergence between urban populations of the crested anole, Anolis cristatellus and their forest-inhabiting counterparts across the island of Puerto Rico. Combining functional genomics, thermal performance assays and common garden experiments we aim to estimate the contributions of plasticity of genetic specialization to differences in thermal tolerance between urban and natural populations. Additionally, we are searching for the genetic mechanisms that have allowed populations to persist in unnaturally hot urban environments for generations.
Genetic architecture of high altitude adaptation:
The cold and hypoxic conditions of high altitude environments impose severe physiological challenges. For small endotherms that live in cold environments, the ability to produce metabolic heat (aerobic thermogenesis) is important for survival. However, hypoxia constrains aerobic thermogenic capacity, compromising the ability to produce metabolic heat under conditions where thermoregulatory demands are particularly high. This ecological setting provides an opportunity to study the evolution and genetic architecture of complex physiology in an adaptive context.
In collaboration with the Cheviron Lab at University of Montana, I am investigating the genetic mechanisms that contribute to enhanced thermogenic capacity of a highland subspecies of the deer mouse, Peromyscus maniculatus under hypoxic conditions. We are utilizing highland-lowland crossing experiments to identify the QTL underlying thermogenic capacity and subordinate physiological traits throughout the oxygen cascade. Additionally, we are investing patterns of gene expression in hybrid mice to quantify the relative roles of cis- and trans-regulatory modifications in producing observed differences in gene expression between the two subspecies.