Diversifying Coevolution and the Adaptive Radiation of Crossbills (Aves: Loxia)

EPA Grant Number: MA916362
Title: Diversifying Coevolution and the Adaptive Radiation of Crossbills (Aves: Loxia)
Investigators: Parchman, Thomas
Institution: New Mexico State University - Main Campus
EPA Project Officer: Zambrana, Jose
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $97,796
RFA: GRO Fellowships for Graduate Environmental Study (2004) RFA Text |  Recipients Lists
Research Category: Academic Fellowships


The role of ecology and species interactions in the production and organization of biological diversity has become a central focus of modern evolutionary biology, ecology, and conservation biology. The objective of this research is to investigate how geographical and ecological variation in predator-prey interactions influences coevolutionary dynamics and patterns of adaptive radiation focusing on the ecologically specialized red crossbills (Aves: Loxia) and the conifers they have evolved to exploit. In particular, I am examining the contribution of predator-prey coevolution to the adaptive diversification of crossbills. Because there is a direct functional link between the bill morphology of crossbills and the cone structure of their conifer resources, I can use foraging experiments with captive crossbills to understand how reciprocal natural selection should act on crossbill morphology and the cone morphology of the conifer species on which they specialize. My previous research taking such an approach revealed that coevolution between crossbills and several conifers occurs only in areas where a preemptive competitor, the red squirrel, is absent and that coevolution in separate systems has occurred in a parallel and replicate fashion. These studies suggest that geographic mosaics of coevolution are important in underlying the adaptive diversification of crossbills and that understanding and characterizing such coevolutionary mosaics is critical to the conservation of specialist species.


My current research is directed at evaluating the contribution of coevolution to the adaptive radiation of crossbills by addressing how ecological context affects the geographic mosaic of coevolution and by using molecular markers to understand patterns of genetic differentiation arising from geographic variation in the form and outcome of coevolutionary interactions. First, previous studies on crossbill-conifer coevolution will be extended to include a wide range of ecological contexts that different crossbills experience (i.e., variation in resource stability and the strength of competition). This work will utilize similar approaches as in the above-mentioned studies but will focus on different crossbill taxa specialized on fluctuating conifers and experiencing different community contexts in western North America and on islands in the Mediterranean and Caribbean regions. In addition, molecular markers will be used to produce a population genetic and phylogenetic framework through which to understand patterns of specialization, coevolution, and diversification throughout the adaptive radiation of crossbills, beginning with the use of AFLP markers to investigate patterns of genetic variation across the North American crossbills. Together with detailed field and laboratory studies of crossbill-conifer interactions for a wide range of crossbill and conifer taxa, my genetic studies will provide tests of the hypothesis that ecological specialization and predator-prey coevolution can drive speciation and will allow me to address the role of coevolution across the adaptive radiation of crossbills. Thus, this research will address the role of geographically structured species interactions and coevolution in the formation and maintenance of biological diversity.

Supplemental Keywords:

fellowship, species interaction, biological diversity, adaptive radiation, coevolution, molecular markers, genetic studies, crossbills., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecosystem/Assessment/Indicators, exploratory research environmental biology, Ecological Effects - Environmental Exposure & Risk, Ecology and Ecosystems, Biology, Ecological Indicators, biological activity, adaption mechanisms, coevolution, biological transformation, gene-environment interaction, biological cycling, additive genetic variation, predator/prey interactions, species diversity, crossbills, conservation biology, species response