DISSERTATION RESEARCH: Phylogenomics and Biogeography of Early-diverging Laniatores (Opiliones) using Ultraconserved Elements

San Diego State University Foundation, San Diego CA

Investigators

Abstract

The spider group known as Opiliones, or harvestmen, is understudied, particularly the suborder Laniatores where the evolutionary relationships among major lineages are uncertain. To date, research on the relationships among major lineages of Laniatores has produced conflicting results in regards to the proper classification. The current research project will use newly developed DNA sequencing technologies combined with fieldwork targeting key harvestmen groups distributed across the world, including a collaboration between researchers in the U.S. and New Zealand. The goals of this research are to reconstruct the evolutionary relationships among these lineages, producing a stable taxonomy, and to infer the biogeographic history of this group in the southern hemisphere, testing specific biogeographic scenarios. By using newly developed methods, this research will establish the UCE approach as a valid and useful method for other harvestmen and arachnid researchers, which may have a potentially transformative effect on harvestmen systematics, and increase the visibility of harvestmen in the broader field of systematics. The field of molecular systematics is transitioning from traditional studies using single- or multi-gene datasets to phylogenomic studies with 100s - 1000s of genes. This increase in the amount of data helps resolve relationships and settle taxonomic issues, particularly in understudied groups like arachnids. This research will attempt to address unresolved systematic and taxonomic issues through a phylogenomic approach using ultraconserved elements. The inclusion of these key taxa whose placement is uncertain coupled with phylogenomics will lead to a stable taxonomy. Additionally, the general biological characteristics of these harvestmen (low dispersal ability and restricted distributions) make them ideal candidates for hypothesis-based biogeographic analyses. The disjunct worldwide distribution and recently estimated divergence times suggest that these lineages are ancient, likely predating the breakup of Pangea.