Collaborative research: Species delimitation, hybridization and the origin of parthenogenesis in Whiptail lizards (Aspidoscelis).

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Species are the basic unit of biological diversity. Scientists must be able to accurately recognize the boundaries between species, and the relationships among them, to understand fundamental biological processes and global patterns of biological diversity. The biology of some organisms makes recognizing species challenging. In particular, when species hybridize in nature it obscures the patterns of morphological and genetic variation that scientists usually use to recognize them. In some cases, hybridization is also associated with unique and interesting biological phenomena, such as changes in reproductive modes, chromosome number, or evolutionary adaptation. In this project, the research team will develop ways to accurately recognize species in a group of lizards where hybridization is common and species identification has been challenging: The North and Central American Whiptail lizards of the genus Aspidoscelis. In addition to improving methods for recognizing species, this research will increase the understanding of the effects of hybridization in the wild, as well as the evolution of reproductive modes in this group of lizards. The research activities will also provide training for a diverse team of scientists and students, many from groups typically underrepresented in science, in Hawaii and California.Whiptails have diversified rapidly and experienced a large amount of introgressive hybridization, which makes them ideal for evaluating phylogenetic and population genetic methods for disentangling hybridization, lineage sorting, and systematic error. Hybridization between gonochoristic species has also repeatedly led to the formation of parthenogenetic lineages at a frequency that is essentially unique to this group. The research team will use genomic and morphological data to disentangle the effects of introgressive hybridization and lineage sorting on the patterns of divergence between all lineages of the Whiptail lizards, and use these results to infer the origins of parthenogenesis across the genus. By examining the geographic, temporal, and genomic dynamics of hybridization and introgression in Whiptails, the project will provide a better understanding of how gene flow impacts the speciation process in nature, and across evolutionary time. Comprehensively resolving patterns of speciation among Whiptails will also shed light on the processes associated with the frequent changes in reproductive mode that make them unique among vertebrates, and contribute to their ability to serve as a model system for other areas of inquiry across the life and biomedical sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.