5 Nov
Darrin Hulsey
Assistant Professor, Department of Ecology and Evolutionary Biology, University of Tennessee Knoxville
Mechanisms and Tempo of Diversification in Cichlid Fishes
Video (QuickTime)
Abstract
The evolutionary novelties in the jaws of cichlid fishes may underlie the putatively unparalleled diversity and ecological success of these icons of adaptive radiation. My research combines molecular phylogenetics, functional ecology, and biomechanics to examine the micro- and macroevolutionary consequences of trophic adaptations for the success of cichlids. During my seminar, I will discuss how several different ecological and evolutionary mechanisms might have structured cichlid diversification.
Bio
My lab studies the evolution of complex morphological phenotypes. Although we work on a large number of aquatic organisms and phenotypes ranging from pectoral fin swimming in Lake Malawi Cichlids to anti-predator defenses in snails, our research is largely concentrated on the feeding apparatus of fish. The jaws of fishes offer an ideal organismal phenotype for examining the forces that structure functional adaptation in a complex system. Within cichlid fishes for example, a huge number of historically independent and convergent trophic phenotypes have arisen through modifications of conserved musculoskeletal elements that comprise their highly kinetic skull. This replicated evolutionary framework provides the power to address broad questions concerning the mechanisms underlying the evolution of ecological novelty.
In both the field and in the lab, we experimentally determine performance capabilities in live organisms to experimentally test if phenotypes we model as simple machines like levers or force-resisting structures exhibit mechanical tradeoffs in vivo. This approach allows us to examine the functional consequences of both predatory abilities and anti-predatory defenses to quantitatively elucidate the mechanistic properties of adaptations in predator-prey interactions. Our work also integrates phylogenetic reconstruction and population genetics to provide evolutionary maps for understanding when and how traits arise. These evolutionary studies that often lie at the interface of micro- and macroevolution allow us to place phenotypic novelties that arise plastically and/or have a genetic basis within a comparative framework. Currently, we are working to incorporate studies of gene expression and quantitative genetics into microevolutionary analyses in order to understand how developmental genetic changes occur within populations where functional novelties arise.
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