The long-term survival of a species is dependent on the genetic diversity of the populations that comprise that species. Any reduction in genetic diversity weakens the ability of a species to adapt to changes in the environment, including emerging diseases or changing climate. Understanding how populations lose genetic diversity, and how they may recover from this loss, is fundamental to conservation efforts. This study will cap a 25-year-long project by addressing the foundational topic of the loss of genetic diversity across 270 generations of an insect (chewing louse) with a very short (33 day) generation time. This insect serves as a model for organisms with much longer generation times; for example, a 270-generation study of rodents would take more than 300 years to complete, and a similar study of human genetics would span more than 5,000 years. The distinct advantage of using this insect as a model organism promises to produce new insights that have the potential to change the way scientists think about changes in species distributions and the effect of this change on the genetic diversity of at-risk species. The study also will provide numerous research opportunities for undergraduate students and will foster discussion at the local level via the establishment of a Science Café for informal interactions between research scientists, students, and the general public.
This study will provide empirical genetic data from a parasitic chewing louse (Geomydoecus aurei) for testing predictions produced by simulation studies. G. aurei is experiencing an ongoing range expansion that dates back at least to the 1920's. The research will take advantage of a library of louse samples collected since 1991, which documents a yearly southward movement of the parasite's geographic distribution of about 200 meters per year. To test models of population expansion, the spatial distribution of genetic variation associated with the population expansion will be compared to spatial genetic variation within the core of the species range. Genetic recovery models will be tested by comparing populations previously bottlenecked by the colonization process with populations from those same locations now embedded within the expanding range of G. aurei.
