Ecological and microevolutionary effects of urban land-use change on butterfly dispersal.

摘要

Dispersal usually is considered an intrinsic species trait, invariant through time and independent of landscape factors. My research highlights that realized dispersal distances may depend on landscape configuration as well as intrinsic capabilities. A critical landscape measure is the connectivity between discrete habitat patches. Through modeling studies, I demonstrate that urban growth in some landscapes can increase habitat connectivity, despite the loss of a high proportion of habitat. Landscapes with a high degree of change in structural attributes such as connectivity, habitat area, and inter-patch distances, can exert high selective pressures on organisms. Using museum specimens of 4 butterfly species collected over the past 100 years, I show that dispersal morphologies may have changed rapidly in response to patterns of urban growth in the San Francisco Bay area. My dissertation research suggests that dispersal should be considered a dynamic trait that interacts with environmental change. Explicit consideration of this dynamic interaction will improve our understanding of the movement and persistence of species in human-dominated landscapes.