Meeting Abstract
Spider chelicerae, which are functionally equivalent to jaws, are a crucial component to spider biology and successful prey capture. Not much is known about the diversity of this trait in spiders, or how the chelicerae have evolved to adapt to different ecological pressures. In this study, we test how the various shapes and orientations of the chelicerae have diversified across the major spider lineages. Our hypothesis is that hunter spiders, because of their reliance on cheliceral performance compared to those that use a snare to capture their prey, have experienced an increased rate of cheliceral trait evolution. We measured seven morphological traits of the cephalothorax for 84 representative spider species. These values were then compiled in a matrix, with which we performed a phylogenetically corrected Principle Component Analysis. We used the first and second PC values to construct a plot visualizing the cheliceral morphospace across spiders. The rate of cheliceral trait evolution was then determined via BAMM analysis, using the three PC values with the highest eigenvalues and our size data. Our preliminary data shows that ground hunting spiders show an increased rate of trait evolution relative to orb weaving and web building spiders. This suggests that the evolution of a hunter lifestyle promoted an adaptive radiation in cheliceral trait morphology.
