9520668 MADDISON The forces that have lead to the great diversity of life on earth are poorly understood. This study will compare the genetics of two species of jumping spiders in an attempt to understand the processes driving speciation. These two species, isolated on the mountain ranges in southeast Arizona, appear to be evolving at a very rapid rate. Their habitat was continuous between the mountain ranges as recently as 10,000 to 14,000 years ago. In this short period, males of one species have diverged considerably. Another closely related species also shows some divergence, but not nearly to such a striking degree. Mitochondrial and nuclear genes will be examined in order to reconstruct the genetic forces that have promoted morphological divergence. The genetic data will be used to test new theories developed in the past ten years. one of these, coalescent theory, attempts to reconstruct the past genetic structure of a species by examining a gene genealogy of that species. The genealogy of mitochondrial DNA has been used in attempts to infer the history of humans, but we know little about how mitochondria evolve in general. This study will add to our knowledge of how mitochondria evolve, which may influence how we interpret future genetic data with this molecule. This study allows a unique opportunity to examine speciation while it is still occurring. The mountain ranges in southeast Arizona are habitats that have become fragmented from each other due to climatic changes. They may provide a model that will lead to better understanding of how populations have responded to range fragmentation in the past. Such understanding will be useful in developing conservation strategies to deal with widespread habitat fragmentation due to human disturbance.
