Living life on the edge: The role of introduction and range expansion in shaping behavior of a non-native spider

Animal personalities describe the behavioral phenotypes of individuals that often remain relatively stable over time and contexts. Since they can account for differential dispersal tendencies, understanding how personality types are distributed across the range can lead to important characterization of expanding invasive populations. Cyrtophora citricola is a colonial tentweb orbweaver spider with an Old World native range that is invasive in Florida. It has experienced a range expansion of over 450 km in 20 years. In my dissertation, I asked whether C. citricola exhibits personality, whether some of its behavioral traits are correlated with dispersal tendencies, and whether personality types are spatially assorted across its range. I found that this spider species does indeed exhibit personality through repeatability in various behavioral traits, and that activity and exploration behaviors were correlated with the latency to engage in ballooning long distance dispersal. I have also shown that individuals at the core of the established population behaviorally differ from those at the two expanding range fronts, although these two populations seem to have diverged in traits. Individuals at the leading edge of their invasive front are faster to attack a prey stimulus and more active. Those in the western population are shyer and less exploratory. These differences suggest that any landscape level range expansion processes such as spatial sorting do not always result in similar patterns of phenotypic divergence from the core population. I also compared behavioral types of native populations of C. citricola in their native range with those in their invasive Florida range, to better determine whether invasive populations are subject to different pressures and processes than those in the native range. In the native range, range was not a significant predictor of behavior, although individual size, site, and colony were. This is consistent with the idea that composition and spatial distribution of native populations might be shaped by local adaptation, whereas expanding introduced population might be influenced by dispersal-influenced phenotypic change. Overall, personality composition at the core of the non-native range resembled that of the native population. This dissertation suggests that personality shifts across the non-native range may be more of a product of range expansion processes, rather than selective pressures from the introduction and establishment process.