Our lab is interested in the evolutionary and ecological processes that generate phenotypic diversity. The focus of our work is to understand how species have evolved traits, such as behavioral strategies and sexual signals, that enable them to maximize fitness despite variability in their environment. We approach this topic from the perspective of behavioral ecology, addressing questions about the function and evolution of sexual traits, the causes of variability in the survival-reproduction tradeoff among individuals, and the factors that drive individual differences in mate choice and competition strategies. Working with some of the most environmentally-sensitive taxa (amphibians and reptiles) has also led us to apply a behavioral ecology framework to conservation. We aim to better understand the adaptations that permit reproduction in novel anthropogenic environments.
Adapting to variable reproductive environments
How do animals cope with challenges during reproduction? Although mating itself typically comprises only a short amount of time relative to an individual’s entire lifespan, how individuals behaviorally and physiologically respond to challenges before, during, and immediately after mating has a disproportionate effect on their fitness. Consequently, selection within unpredictable environments has repeatedly led to the evolution of flexible, instead of hard-and-fast, tactics of mate choice and competition. Using wood frogs (Rana sylvatica), we examine how behavioral strategies have diversified in a scramble mating system. Male wood frog competitive strategies are sensitive to conspecific density and sex ratio (both of which fluctuate rapidly and unpredictably). We investigate the function of these shifts in strategy and the corresponding tradeoffs experienced by individuals. Ongoing research aims to examine the adaptations that have allowed wood frog breeding aggregations to thrive in highly-modified, suburban habitats.
Challenges experienced in mate choice-based systems are dissimilar, but no less impactful, than those experienced in scramble breeding aggregations. We use fence lizards, Sceloporus undulatus, to test the impacts of phenotypic variability on choice and competition strategies. Our work focuses on identifying how individuals use information to inform decisions during inter- and intra-sexual competition, in conjunction with examining the function and evolution of sexual traits [see below].
The consequences of mate choice and competition
A rich, rapidly-expanding body of literature uses theoretical and modeling approaches to understand the link between mate choice or competition and an individual’s fitness. Building from this base, we empirically test the connection of pre-mating decision-making (e.g., who to mate with, how often, or how much to fight for mate access) with variation in offspring fitness. For example, conflicting predictions can be made regarding the effect of sex ratio on offspring fitness in dense breeding aggregations: does it effectively “filter out” less-fit males (enhancing offspring fitness) or increase stress in females (reducing offspring fitness)? By manipulating wood frog breeding aggregations, we are able to robustly tackle this question in the field.
Identifying the fitness consequences of reproductive decisions is not straightforward, as species often have strategies allowing them to cope with suboptimal matings. As wood frogs are notoriously constrained in their mate choice, we explore how mate choice constraints directly affect offspring fitness, and if there are mechanisms in place that enable an individual to compensate for a suboptimal mating.
The function of sexual signals
To understand why species look and act how they do, we investigate one of the evolutionary forces that shaped them: sexual selection. We examine the mechanisms of sexual selection by taking a functional approach: what role do exaggerated traits (particularly conspicuous coloration) serve in animal communication, and what are the fitness tradeoffs of social signaling? The water anole, Anolis aquaticus, lives on the banks of small streams in a heterogeneous signaling environment. Ongoing projects with this species involve identifying the information content of its orange-red dewlap and the drivers and potential social relevance of its lateral stripe’s rapid color change – from dark brown to bright blue/green in less than a minute.
Our work on the sexual coloration of Sceloporus undulatus is geared at identifying the cost/benefit tradeoffs and functionality of the blue ventral badges in both males and females. Whereas female fence lizards prefer mates with larger badges, females that bear this male-typical trait (the so-called “bearded ladies”) are often rejected by males and accrue substantial fitness costs. Color badges in this species change hue relatively quickly with temperature; we are interested in uncovering the social significance of this green-to-blue switch and its function in mate choice and competition.
Please see the publications page to learn more about our research.