Collaborative Research: Species delimitation in North American lizards

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Species are a fundamental unit of diversity in the natural world. Therefore, accurately documenting species diversity has important implications in life sciences, habitat management, and conservation. Yet, despite the importance of species in understanding biodiversity, it is often difficult to identify unambiguous species boundaries in many taxonomic groups. Lizards are one such example of a taxonomic group with genetically-different populations that often look very similar. What appears to be one lizard species is often a species group of several possible lizard species. In this project, the researchers will collaborate with scientists across 15 different institutions to determine species boundaries in 30 species groups of North American lizards. Doing so will (1) connect scientific understandings of how species form to the practice of naming species and (2) model an intellectual and methodological framework for naming species consistently in other taxonomic groups. The researchers will share their research findings at community events across three metropolitan regions, engage undergraduate students in authentic research, and guide taxonomic revisions to promote stable species names.This project will use an integrative approach to delimit species. First, the project team will collaborate with taxonomic experts to generate range-wide genetic, ecological, and morphological sampling for each focal species group. These data will then be analyzed consistently to characterize levels of genetic and phenotypic divergence within each species complex. Then, the project team will assay levels of reproductive isolation between candidate species by using genetic data to measure the extent of hybridization and introgression between them. By comparing data on divergence and isolation, the team will characterize the rate and pace at which reproductive isolation evolves. Using these estimates, the team will then define the population-species boundary and apply it to the 30 focal groups to identify taxonomic units that show the highest levels of durability through time. Finally, using the revised taxonomy, the team will evaluate species delimitation methods that define taxonomic units based solely on genetic data. While efficient, these methods can be biased, and this analysis will identify the potential causes for these biases.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.