Welcome to my lab website. I am an evolutionary biologist with considerable experience in marine systems. My research has drawn on a variety of methods and data, but the approach and tools of Molecular Ecology unites most of the ongoing work in my lab.
I have recently moved to Bowdoin College as the new Director of the Bowdoin Marine Laboratory (BML). The BML is part of Bowdoin’s Coastal Studies Center (http://www.bowdoin.edu/coastal-studies-center/), located on Orr’s Island, a 20 minute drive from the Bowdoin Campus in Brunswick, Maine. The CSC is conserving 118 acres of coastal pine forest that is located on a pennisula that extends into Harpswell Sound. As a consequence we have outstanding access to both terrestrial and estuarine marine environments. A research pier brings seawater to our Marine Lab building and serves at the launching point for estuarine and coastal research via small boats. See the Bowdoin Marine Laboratory page for a fun slideshow of facilities, environments, and organisms.
Many have asked me: “Dave, you know it snows in Maine”…and my response is that YES…I am familiar with freezing precipitation. I grew up in Upstate NY and was an undergraduate and graduate student in the New England area. But thank you for your concerns of whether I can still thermoregulate. I will maintain and adjunct position in the Biology Department at the University of Hawaii where I will continue to advise and 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.
OK, so what am I working on these days? Below I describe three active research areas:
Speciation I am interested in what Darwin called that “mystery of mysteries” or how populations make the transition to new species. Recently, my group has been integrating the fossil record with molecular phylogeny to deconstruct rapid speciation and adaptive radiation (Schwartz et al. 2012). We also take a microevolutionary view of speciation by capitalizing on incipient species of corals and parrotfish in order to understand contemporary forces that drive reproductive isolation, including natural selection, sexual selection, and genetic drift.
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.