We study the ecology and evolution of non-model organisms to better understand how biodiversity tends to evolve. Our work blends computational biology with field biology and evolutionary ecology with evolutionary genetics, and we address fundamental questions surrounding the mechanisms that generate observable patterns of species richness.

Conceptually, our work is organized around a basic premise, which is that for biodiversity to arise and accumulate, two processes must occur. First, lineages must split into two or more descendants (however defined), and second, descendant lineages must establish overlapping ranges. Speciation and the establishment of sympatry are then two critical rate-limiting steps in the diversification cycle. The primary focus of our work is to better understand the factors affecting both processes.

Practically, we work with a variety of organisms and data types. One component of our research involves the fine-grained investigation of genomic and ecological patterns in individual lineages pairs (ranging from wild drosophilids to butterfies to fishes); other questions involve large-scale data syntheses and comparative analyses, which often necessitate the development of novel statistical approaches; and still another component of our work involves the construction of mechanistic theory to generate testable predictions.

A non-exhaustive list of recent and on-going research themes are:

  • The role of adaptive ecological divergence during speciation and the establishment of sympatry
  • The role of ecological differences in preventing lineage fusion upon secondary contact
  • Factors affecting speciation reversal
  • The relationship (or lack thereof) between organismal RI (mechanisms like hybrid sterility or assortative mating) and evolutionary RI (the extent of independent evolution across two genomes)
  • The relationship between evolutionary RI as measured across contemporary hybrids zones and over deeper timescales
  • Understanding the speciation continuum from the perspective of both organismal and evolutionary RI

Our current work is framed in the context of a revolution in our understanding of speciation that has emerged in the genomic age and that is not yet near complete. For instance, just prior to the routine publication of whole genomes, Coyne and Orr (2004) exhaustively surveyed the speciation literature and concluded “our guess is that morphologically distinct taxa showing rampant gene exchange at many loci will be rare” (p.41). We now know that such data are commonplace, that strong organismal RI doesn’t always translate into reduced gene flow – and, most radically (in the context of Modern Synthesis thought), that stable co-occurrence between diagnosable taxa does not imply a lack of introgression. Diagnostic trait differences can indeed be maintained despite weak evolutionary RI.

A key priority in our current age is thus to develop research questions that (1) treat RI as continuous rather than discrete, (2) recognize the reversibility of the proecess, and (3) are, rather paradoxically, agnostic about species status. One question that meets these criteria also forms the unifying question of our current work: how and why does the extent of independent evolution across the genomes of two lineages rise or fall over time?