Research

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We are motivated by a fundamental observation in nature: Evolution proceeds unequally! Whereas some genes, traits, and lineages diversify rapidly, others can remain inert (or nearly so) for millions of years. But, why is this true? Why do some traits and lineages achieve evolutionary overdrive while others appear to be stuck in the slow lane? The primary goal of my lab is to answer this question by linking ecological processes with evolutionary patterns. We approach this goal primarily through the lenses of evolutionary physiology, and biomechanics. Below are a few of our major current topics of research:

 

A. Evolutionary Dynamics of Adaptive Radiation

Anoles have diversified across elevations into distinct thermal macrohabitats.  Additionally, diversification has also occurred along the sun-shade axis into distinct thermal microhabitats. Thus, some species have specialized to cool and/or hot environments at the macro and microhabitat scale.

Islands are important cradles for biodiversity. They’re home to many strikingly diverse adaptive radiations, such as the Hawaiian silverswords and honeycreepers, Darwin’s finches, and one of our personal favorites, Anolis lizards from the Caribbean. The adaptive radiation of Caribbean anoles is known for the evolution of distinct ‘ecomorphs’, so-named based on the tight association between structural habitat use and morphological traits in these lizards.  Yet, what we’re discovering is that thermal physiology is just as important as morphology for the diversification of Anolis lizards. Anoles have diversified into various thermal niches, as well as structural niches. Currently, graduate student Brooke Bodensteiner is working out the temporal dynamics of trait diversification. Although her work is still ongoing, she is discovering that the tempo and mode of physiological and morphological evolution impart distinct signatures of anole diversity. Stay tuned for more!

Undergraduate Jhan Salazar recently tested whether island lizards have faster rates of physiological evolution than mainland anoles. Due to ecological opportunity, island lineages are well known for fast rates of trait evolution. Surprisingly, however, they discovered slower rates of heat tolerance evolution in the island lineages. Moreover, island anoles are evolving towards higher trait optima. The results are largely explained by greater thermoregulation on islands. Despite island and mainland anoles occurring in similar thermal environments, island lizards thermoregulate more. The major result from this study (currently in revision) is that ecological opportunity (release from predators and competitors) on islands can reduce the intrinsic costs of thermoregulation. The surprising result, therefore, is that ecological opportunity may actually slow, rather than accelerate, trait evolution!

B. Ecological and Evolutionary Responses to Climate Change
Climate change is already having a tremendous impact on biodiversity worldwide, resulting in range shifts, localized extirpation, and even extinction events. However, the role that climate change plays in altering biodiversity is not always clear cut. Species can be directly impacted by increasing temperature, or indirectly impacted through alterations to abiotic and biotic interactions. Postdoc Vincent Farallo is using mechanistic niche models, which incorporate species-specific physiology and behavior data, to determine how montane Anolis lizards from the island of Hispaniola will alter their activity time based on climate change scenarios. The mechanistic models allow us to tease apart the direct and indirect effects of climate change. The lab has also started collecting physiology data for lungless salamanders from the Appalachian Mountains, specifically the Plethodon cinereus group. The group contains montane endemics with very restricted ranges, as well as widespread species.

Species from the Plethodon cinereus group vary widely in their distribution size from over 1 million km2 to less then 50 km2. Our goal is to understand how these species will respond to climate change including how species interactions may shift.

The lab’s goal is to use these techniques to help guide conservation efforts of these range limited species including understanding how interactions between montane endemics and widespread species may be altered with the changing climate. We will also assess how the physiological traits of these species have evolved which will help determine if adaptation to rapidly changing conditions is possible.

Photo b y Jhan Salazar
Anolis chloris taken by Jhan Salazar