A grant has been awarded to Dr. Susan Masta of Portland State University and her colleague Dr. Jeffrey Boore (DOE Joint Genome Institute) to examine phylogenetic relationships among the 11 orders of arachnids (spiders, mites, scorpions, and relatives). Arachnids are one of the four major groups of arthropods, are of ancient origin (ca. 450-500 million years ago) and are highly diverse (over 97,000 described species). However, little systematic work has focused on deciphering the relationships among the orders of Class Arachnida, and their relationships remain enigmatic. This project will sequence and analyze whole mitochondrial genomes of 42 species sampled from across the 11 orders of Class Arachnida. To infer genealogical relationships among the orders, the research will use sequence data as well as novel genome-level characters ("rare genomic changes" such as changes in gene order, gene content, and RNA secondary structure). Preliminary data suggests these genome-level characters are capable of resolving the ancient divergences among arachnids. An accompanying analysis of morphological characters by Dr. Jeffrey Shultz (University of Maryland) will further extend the number of characters that can be used to infer relationships among these organisms.
By elucidating phylogenetic relationships, the investigators expect to advance the systematic understanding of arachnids, and thereby provide crucial context to numerous basic and applied biological studies. Arachnids show unusual and highly derived traits that are of interest as evolutionary innovations and that may hold promise for applications in biotechnology. For instance, venom components from some scorpions have been shown to have antibacterial properties and to inhibit development of malaria parasites, while the silks of spiders include the strongest fibers known. Understanding how such traits evolved requires a robust arachnid phylogeny. The work will also reach beyond the scientific research community. Arachnids, particularly spiders and scorpions, are of interest to the public, and our results will be made available via a project webpage. The project will also provide training in the techniques and concepts of systematics and genomics to undergraduate and graduate students at Portland State University. Such training addresses an urgent need, as systematists begin to utilize data from comparative genomics. In addition to incorporating students into all aspects of the research, results from this work are being integrated into new courses for undergraduate and graduate students. These courses allow hands-on analyses of newly generated sequences to teach gene annotation, alignment, and phylogenetic analysis, skills crucial in making sense of today's burgeoning amount of genomic data.
