Where divergent evolutionary lineages come into geographic contact and have the opportunity to interbreed, they often remain distinct because of genetic differences that reduce the probability of successful mating between lineages or reduce the fitness of hybrid offspring. Speciation is the process by which lineages diverge and become reproductively isolated and is the basis for the accumulation of biodiversity. A complete understanding of speciation requires knowledge of the genetic basis and evolution of reproductive isolation. The proposed research will characterize the genetic basis and evolution of reproductive isolation between the butterfly species Lycaeides idas and L. melissa. The goals of this research are to determine the number, distribution, and effects of genetic regions isolating these species, and the role of natural selection in their divergence. Genetic regions associated with reproductive isolation will be identified using novel statistical analyses of gene flow in populations with hybrids between the two species. These genetic regions will then be contrasted with regions showing evidence of natural selection in geographically isolated populations.
This project will provide insight into the genetic basis of reproductive isolation and the role of natural selection in the speciation process. The project will further develop statistical methods for evolutionary genetics, which will be made available to the scientific community as computer software. Participation of undergraduates and K-12 teachers in the research will be a priority and will involve computational work with participants in the University of Wyoming summer bioinformatics program and fieldwork with local teachers.
Our research on butterflies provides strong evidence that speciation is aided by natural selection and adaptation to alternative environments. Previously this long-standing evolutionary hypothesis had received considerable support at the level of individual traits and genes that contribute to speciation. Importantly, our research showed that this hypothesis holds at many genetic regions across the genome. Furthermore, our study provided evidence that the processes of speciation and adaptation to alternative environments have highly variable consequences for the genomes of diverging organisms. This work is important because it enhances our understanding of how evolution proceeds and genomic divergence occurs as populations and species evolve independently. The work was made possible by very recent advances in laboratory technology that allowed us to assay the genome at much finer scales, and revealed unanticipated variability throughout the genome. The results of this work have now been published in several journal articles. Beyond these evolutionary findings, for our research we developed novel methods and software for analyzing genome variation. These should facilitate further progress in evolutionary and population genomics. In addition to the training of Gompert in his Ph.D., this research provided three Wyoming K-12 teachers with training in field biology, data analysis, and computational biology. Additionally, software was developed and distributed, and a teaching module was developed and disseminated.
