Friday, August 10, 2007 - 9:00 AM

COS 146-4: Morphological correlates of dispersal in Odonata

Shannon J. McCauley, University of California, Davis

Dispersal is a critical process affecting species distributions, community structure, and the persistence of spatially structured populations.  Despite the central importance of dispersal in population and community ecology, our understanding of dispersal processes is highly limited for many taxa.  Extensive research on the relationship between species traits and local performance has led to predictive frameworks that provide insight into the mechanisms determining community composition (e.g., activity level - mortality risk trade-offs and species sorting across habitat gradients) but similar approaches have rarely been applied to understanding how species traits are related to dispersal behavior.  I examined the relationship between dispersal behavior, measured in a field experiment, and morphological traits expected to affect flight performance in odonates including patterns of allocation to wings and the thorax.  These comparisons indicate that species that dispersed more often and farther from their source habitats had relatively larger thoraces.  Additionally, wing morphology was related to dispersal behavior but these patterns were less consistent and suggest that there may be alternative morphologies associated with gliding versus powered flight.  Comparisons of wing morphology within a single genus, Libellula, found that both wing size and wing shape were related to dispersal behavior.  These results suggest that understanding the functional relationships between morphology and flight performance may provide a framework for making predictions about dispersal performance in odonates and other groups of flying insects.  Finally, I present preliminary data on intraspecific comparisons that assess the relationship between individual characteristics and dispersal behavior.