Welcome to my research lab website. I am an an evolutionary biologist primarily interested in micro-evolution. I have an inordinate fondness for marine organisms, but have dabbled in some intriguing terrestrial systems, including the Hawaiian flycatcher radiation. My research has drawn on a variety of methods, but the approach and tools of Molecular Ecology unites ongoing work in my lab.
After 10 years of teaching and research at the University of Hawaii, I moved to the slightly colder waters of Maine in the Summer of 2013 to take the Directorship of the Coastal Studies Center (CSC) at Bowdoin College. The Coastal Studies Center has an outstanding natural setting to understand human impacts in the Gulf of Maine Ecosystem: including invasive species, overfishing, and climate change. Given our geographic position and these societal needs, we are growing research facilities and teaching programs to serve the Bowdoin Community as well as visiting researchers. See the CSC webpages for our latest developments. In addition to holding a faculty position in Bowdoin’s Biology Department, I have an adjunct position at the University of Hawaii so I can continue to work with a great team of graduate students. You can see their bios and get a sense of what they do from the Lab Members page.
Below I describe three active areas of research:
Speciation I continue to work in systems of “new” species where genes can (and do) cross phenotypic boundaries. The tension between the homogenizing effects of gene flow and the diversifying effects of reproductive isolation in such systems provides unique insights into the speciation process and sometimes its reversal. My colleagues and I have uncovered a new parrotfish hybrid swarm in the Eastern Pacific, that may potentially be the world’s largest hybrid zone: stretching over 3500 kms between Baja California to the Galapagos Islands. We are currently using the illumina NGS platform and UCE markers to determine the extent of gene flow across genomes, and increasing our geographic sampling to understand the spatial context of hybridization. Our team includes Ross Robertson (STRI), Carlos Armando Sanchez (UABCS, Mexico), Howard Choat (JCU, Townsville), and Kendall Clements (U. of Aukland, New Zealand).
Evolutionary applications Climate change will exert an enormous selective gradient on natural populations. Evolutionary quantitative genetics provides a framework to predict how organisms will respond from organismal and population perspectives. Since the response to changing environments can involve both physiological and evolutionary components, we will need estimates of the amount of quantitative genetic variation (heritability in the narrow sense) in traits under selection in natural populations. It is this later quantity, combined with genetic correlations among traits, that sets the rate of the evolutionary response. Traditional methods for estimating heritability and genetic correlations require laboratory crosses and culture over many generations, the foundation of quantitative genetics. Yet for many of the species that provide ecosystem services, or that are ecosystem engineers, or bring so much aesthetic value to our lives, such crosses and culture are just not possible. A solution to this problem is to develop estimators of heritability in the wild, and I have been contributing to this field by the development and application of marker-based methods to wild populations (Carlon et al. 2011). These marker-based methods, and newer developments springing from applications of next generation sequencing to “de novo” systems, hold the key to predicting the evolutionary response of many natural populations in the face of rapid climate change.
Conservation genetics The molecular tool kit plays an increasingly important role in identifying fundamental units of conservation. Some examples from my lab include John Fitzpatrick’s thesis work (Fitzpatrick et al, 2011), which strongly suggests new species or sub-species in Hawaii and the Eastern Pacific within the species formerly described as S. rubroviolaceus. As in other fisheries stocks, efforts are under way to document life history and phenotypic evolution among these distinct populations. A second interesting example from my lab comes from a collaborative study of a flycatcher complex (the “Elepaio” or Chasiempis sandwichensisis) in which divergence in phenotypic traits and song variation has been well described among the Main Hawaiian Islands by Eric Vanderwerf and colleagues. Two mitochondrial genes suggest a complex of at least three sibling species each endemic to different island (Vanderwerf et al. 2009). Recognizing the conservation and evolutionary significance of the Oahu species is particularly timely. Relentless urban and agricultural development during the last century has reduced population size to < 2000 birds which occupy an estimated 4% of its former range. In addition to identifying the spatial distribution of potential conservation units, there is historical information contained in DNA sequence data that can greatly informs the design of parks and reserves. Maturing coalescent-based population genetic approaches can evaluate models that include both isolation and gene flow. Thereby providing more biological reality and more robust estimates of connectivity among populations or species than traditional frequency-based methods. I am keen to collaborate with ecologists and systematic biologists who are interested in the application of these kinds of approaches to their particular system.