Research

Research in the Mahler Lab is diverse, but tends to fall within the following major areas.

Phenotypic Macroevolution

What factors ultimately determine the patterns of phenotypic diversity that we observe among branches of the Tree of Life? Research in the Mahler Lab uses a phylogenetic comparative approach to test hypotheses about the determinants of phenotypic diversity. We ask questions such as:

  • Do ecological interactions influence the rate or outcome of trait evolution over million-year timescales?
  • How common is convergent evolution, and what factors promote or prevent it?
  • When do the many traits of an organism co-evolve as an integrated unit, and when do they evolve independently (e.g., as distinct modules)?
  • How do life history and sexual selection affect the evolution of trait diversity?

Our lab is set up to collect a broad diversity of phenotypic data from anoles and other organisms, including morphology, colour and pattern, performance, and behaviour. We also build phylogenies, and we merge phylogenetic and phenotypic techniques to test hypotheses about the drivers of trait diversity.

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Matched Anolis species that evolved on different Greater Antillean islands.

Macroevolution and Community Ecology

What role does evolutionary history play in the assembly of ecological communities? Ecology textbooks have long focused on local factors as the main determinants of community structure (e.g., competition, predation, or local climate). However, we’ve known since at least the 1980s that this view is incomplete – historical and stochastic factors may also play important roles. Despite recent interest, the influence of macroevolutionary history on local community structure remains poorly understood.

Since 2016, the Mahler Lab has led a massive field survey effort to understand how local communities of Anolis lizards vary across biogeographic gradients and among faunas with deeply divergent evolutionary histories. Because independent clades of anoles occupy similar habitats across the Neotropics, they provide a unique opportunity to ask how evolutionary history shapes community ecology at both the local and regional scale. Working with lab alum Luke Frishkoff and his lab at U. Texas at Arlington, we have used mark-resample techniques to measure anole community structure across broad ecological gradients in the Dominican Republic, Jamaica, Ecuador, Costa Rica, and Texas. In addition to shedding light on how history shapes ecological communities, this work is revealing how human activities are restructuring communities in the Anthropocene.

Beta diversity among Dominican anole communities differs between natural and human-modified habitats – conversion of forest to pasture homogenizes communities, depressing beta diversity (a). This effect is strongest when comparing communities from different elevations (b). Even the highest and lowest-elevation pasture communities are relatively similar, unlike their forest counterparts.

Natural History of Anolis, and Other Reptiles and Amphibians

My interest in biology stems from a lifelong love of organisms (especially reptiles and amphibians) and information about the natural history of lizards forms the foundation for much of my work. I study the morphology and ecology of Anolis lizards during field expeditions throughout the neotropics, and this work has led to new discoveries about the natural history of species (e.g., Mahler and Glor 2011; Losos et al. 2012; Stuart et al. 2012), and even to the discovery of previously unknown species (Mahler et al., 2016). Most recently, our lab co-discovered and investigated a remarkable new vertebrate respiratory strategy – underwater “rebreathing”!

Taking data on Anolis lemurinus in Chiapas, México.
Taking data on Anolis lemurinus in Chiapas, México.