RESEARCH INTERESTS:


A wonder and appreciation for the impressive diversity of animal coloration is broadly shared and continues to inspire people of all ages.

It takes a truly multidisciplinary approach to address topics in evolution, ecology, population genetics/genomics, speciation and conservation. My research aims to understand the mechanisms that promote and maintain divergence between populations on fine scales, as well as broad scale patterns of divergence across species using visual signals as focal traits under selection.

In studying visual signals I am able to gain unparalleled evolutionary insights by studying signals that be can readily quantified, where we can measure how and when selection acts on a single focal trait, where divergence in that very trait can directly contribute to reproductive isolation and speciation.

A critical aspect of understanding the process of speciation remains elucidating when sources of selection act to promote or maintain divergence, and when diverging lineages coalesce. My current interests aim to address some of these gaps.


IDENTIFYING PATTERNS OF VISUAL SIGNAL DIVERGENCE ON LARGE SCALES:


Using a large data set of Australian agamid (dragon) lizards I have been examining the contribution of natural and sexual selection on color pattern evolution. Of particular interest is the response of pattern complexity driven by local adaptation to a diverse suite of ecological conditions. Using species distribution modeling approaches I’m able to look at how color patterns respond to habitat heterogeneity (niche breadth), whether ecological character displacement between related species diversifies color patterns, and describe overall patterns of niche conservatism or divergence across diverse lineages.

Ongoing research collaborative projects in the Edwards lab include addressing patterns of phenotypic and genotypic divergence and patterns of color polymorphism in the Side-blotch lizard Uta stansburiana. Preliminary quantitative color analyses revealed strikingly high variance between classic ‘morph’ groups involved in the “rock-paper-scissors” game. I am currently applying a series of visual modeling, visual acuity experiments and RNA sequencing techniques to assess the contribution of color vision to visual signal complexity.


FINE-SCALE PATTERNS OF VISUAL SIGNAL DIVERGENCE:


For my dissertation I investigated the mechanisms that promote and maintain within-population color polymorphism. By focusing on a polymorphic population of Oophaga pumilio I have investigated two anti-predatory strategies through the use of a series of behavioral experiments to assess the contribution of natural selection to signal divergence. Using cline analyses techniques I assessed admixed genotypic and phenotypic transitions across a polymorphic region, including cryptic and conspicuous aposematic color patterns, to demonstrate the role (or lack there of) that coloration plays in maintaining population structure. I also assessed the effects of variation in habitat quality affects a suite of traits under selection including diet, dermal carotenoid and alkaloid profiles, and frog coloration as viewed by conspecifics and potential predators.

I have previously investigated a fascinating case of Müllerian mimicry in the Peruvian poison frog Ranitomeya imitator. In this mimetic radiation, R. imitator mimics several related species (R. fantastica, R. summersi, R. variabilis and R. ventrimaculata) throughout its range. Using molecular techniques coupled with phenotypic (both color and pattern) analyses we demonstrated phenotypic divergence between R. imitator morphs and convergence between R. imitator and model species. We also investigated the population genetics of R. imitator throughout their mimetic radiation, and demonstrated selection acting to promote phenotypic divergence using coalescent simulations.