Research



     Knowing how organisms adapt to change is fundamental to understanding the patterns and processes underlying organismal biodiversity, particularly dramatic changes. Dramatic environmental changes provide new ecological opportunities that have driven some of the most spectacular adaptive radiations on the planet. Why some members of a community can cope with change through adapting where others do not has, and will have in the future, significant implications for species evolutionary potential. Species life history strategies, phenotype, ecological preferences and physiological limits are key determinants of effective dispersal in an organism, but these factors are often overlooked as the basis of variance amongst species responses in comparative studies assessing the impacts of historical phenomena on patterns of population divergence and historical demography within communities.

While most comparative studies of between and within species phenomena focus on how species within a community may be “similar” in pattern (i.e., common vicariance), my research has sought to highlight why species may be different. I have sought to cultivate a research program focusing on the evolutionary responses of species to historical processes as a result of life history, ecological and morphological differences in a comparative context. I am primarily interested in two interconnected evolutionary research areas:


1)         Reconstructing the influence of historical biogeographic processes across vertebrate communities as a means to assess how environmental, life history and phenotypic factors affect the evolutionary trajectories of species.

2)         Understanding the interplay between environment, phenotype, species interactions and the demographic history of species in generating biodiversity, speciation and local adaptation.


My research looks at these research foci at continent-wide, regional and landscape scales using small vertebrate, and primarily herpetofaunal, systems to answer consequential evolutionary questions utilizing integrative data sets and innovative methods. However, the approaches I use may be applied to any system of interest. I have employed an interdisciplinary approach in my research incorporating the analysis of life history variation, morphology, species interactions, ecological preferences, and how these factors influence species’ demographic histories and patterns of inter- and intra-specific divergence. This has given me an interest in how and why species are able to adapt to change, and what molecular and functional mechanisms allow species to change. These two, interconnected questions are particularly important in understanding historical evolution in spatially and temporally transient environments, and are also inextricably linked to the kinds of processes that are likely to be important determinants in if and how organisms will cope with future climatic dynamism.


Giant Galápagos tortoise evolution
   
  My current research in the lab of Dr. Gisella Caccone at Yale focusses on giant Galápagos tortoises. I am currently building a species tree for the radiation using massively parallel sequencing techniques I have adapted for the Ion Torrent PGM, and ddRAD sequencing. I hope to use this species tree to better resolve the evolutionary relationships among giant Galápagos tortoise species, their biogeographic history, and to reconstruct the influence of ecology on the evolution of carapace phenotypes. We are also using the ddRAD sequencing to develop a suite of SNP markers to diagnose  individuals of conservation importance from Volcano Wolf (thanks to some generous funding from the Galapagos Conservancy), which involves the incorporation of NGS approaches using ancient DNA from sub-fossil remains and museum specimens collected in the early 1900's. I am also involved in the Lonesome George Genome sequencing project, and would like to explore the more functional molecular aspects of phenotypic differences in the radiation using a combination of different genomic data sets. These projects are currently underway, so come back soon for some updates!




Sunset on Dirk Hartog Island, Western Australia



Phenotype, environment, species interactions and evolution
   
     How natural selection acts to limit species to particular environments, control species' distributions and shapes species' phenotypes are fundamental underpinnings of the study of evolution and speciation. I am interested in reconstructing the patterns of morphological evolution within and between species, and looking at how environmental conditions drive phenotypic evolution. I am also interested in the molecular mechanisms which cause phenotypic change and what might underly the ability of some species to change, where others do not. I have a couple of different projects in this area over different spatial and temporal scales and ranging from across different taxa and between species at continental scales to between populations at a landscape level. My research in this area is also leading me into thinking about how natural and sexual selection combine forces to drive adaptive diversification - this is a new and developing direction for me which I would like to continue.



Domed Giant Galápagos Tortoise - species unknown


Ecology, life history, phenotype & biogeography
   
     I have studied biogeographic processes across many spatial scales from landscape scales to continent-wide studies, with a common theme of testing biogeographic hypotheses across taxa with disparate life history strategies, ecological preferences and physiological requirements. While, a large portion of my biogeographic research has focused on deciphering the biogeographic history of the south-western Australian biodiversity hotspot, I have also worked on species occupying the Australian wet tropics, eastern Australia, and more recently across the arid zone of Australia and the Galápagos Archipelago. I have worked on most vertebrate groups within Australia, including amphibians, reptiles and most recently dasyurid marsupials. However, the majority of my current Australian research centers on reptilian systems, as these are some of the most diverse systems within Australia in terms of in species number, phenotypic traits, ecological preferences and life history strategies. I use these systems test the role of species ecology, phenotype & life history on biogeographic responses. I am particularly interested in linking these studies with an understanding of local adaptation and its role in population divergence, especially in extreme environments. 





Ctenophorus maculatus dualis - Picture drawn by my sister Corrine Edwards