Evolutionary History of Spiders and Scorpions: Temporal Diversification of Mesh-web Spiders and Western North American Scorpions
Rosemary Gillespie, Professor
Environmental Science, Policy and Management
Closed. This professor is continuing with Spring 2024 apprentices on this project; no new apprentices needed for Fall 2024.
There are two key projects here:
(1) Temporal Diversification and Evolutionary History of the Cribellum in Mesh-web Spiders: Webs play many essential roles in spider biology, including communication, prey capture, locomotion, and reproduction. One interesting morphological feature of many spiders is the cribellum, a plate located near the silk-producing structures called spinnerets, and used to create a special type of matted silk that captures prey mechanically, instead of with glue droplets used by many orb-weaving spiders. The cribellum is hypothesized to have been present in the ancestor of all araneomorph spiders, but lost multiple times over the course of spider evolution. One group of spiders, the ‘marronoids’, shows a pattern of repeated loss and gain of this structure, placing them at a transitional position in the evolution of spider webs, with further implications for the web capture strategy, and other ecological conditions such as water-associated habitat. Studying the timing of the loss of the cribellum may yield insight to the cryptic ecology and morphology of the marranoid clade, and more broadly, araneomorph spiders. This project uses phylogenetic methods to understand patterns of evolution of the cribellum and aquatic habitat associations in the context of geologic events and a time-calibrated evolutionary history.
(2) Western North American Scorpion Phylogenetics: Scorpions have been a frequent target of interest within and outside of the scientific research community. Scorpions belonging to the genus Paruroctonus range broadly from northern Mexico to Canada. Scorpions in the genus exhibit both hyper-endemism in extreme habitats like alkaline flats and sand dunes, and conversely extremely wide ranges distributed across multiple ecosystems. One example of this geological spread is Paruroctonus boreus (Girard, 1854), the northernmost distributed scorpion in the world. Despite species within this genus frequently being used as a model for a wide range of scorpion ecology and physiology studies, the relationships within the genus and the species boundaries have never been tested using modern methods. This research uses the original type series, as well as specimens spanning the distribution of Paruroctonus species in order to infer a phylogeny and test the validity of the species groups that currently exist based solely on morphology. By understanding species-level relationships of Paruroctonus, we can further our understanding of this model genus, and what we know about their ecology and physiology in the context of evolution.
Role: Students that take part in project (1) will code morphological characters from spider specimens and behavioral characters from the scientific literature to generate data for phylogenetic analysis; and (2) engage in molecular work such as DNA extraction and Sanger sequencing methods to generate data for a phylogenetic analysis.
Qualifications: Applicants should be organized, detail-oriented, and able to work independently. Some background or interest in arachnology, entomology, or molecular methods is recommended but not required.
Day-to-day supervisor for this project: Lauren Esposito, Staff Researcher
Hours: to be negotiated
Off-Campus Research Site: California Academy of Sciences
Related website: https://www.calacademy.org/staff/ibss/entomology/lauren-esposito
Biological & Health Sciences Environmental Issues