Description
Oceanic and continental islands such as desert oases are excellent places to observe the interplay between isolation, selection, and rapid evolution. In particular, the western United States contains many island habitats where rapid evolution has been observed in other species, such as the Hawaiian Islands, the California Channel Islands, and the isolated oases of the Mojave and Great Basin deserts. These regions are home to the Habronattus tarsalis species complex, a morphologically diverse but poorly studied group of jumping spiders (Salticidae) consisting of five nominal species placed within the H. americanus group. Analyses of genetic and morphological data for this group found support for the monophyly of the H. tarsalis complex. However, H. tarsalis is not monophyletic and is split into several phylogeographic groups, many of which correspond to the drainage basins in which they are found. This suggests the desertification of the western United States has had a profound impact on the isolation and divergence of these groups. Additionally, analysis of previously published transcriptome data dates the H. tarsalis complex at 1.55 – 0.75 Ma, indicating rapid evolution of these phylogeographic groups. Further studies of the tarsalis subgroup would likely bring enough evidence to support the split of H. tarsalis into additional species and shed more light on the introgression dynamics within the group.
