Thursday, June 7, 2007 - 11:45 AM
394

I used to think that sinkholes are islands, but I grew out of it: dragonflies experience an ontogenetic shift in landscape function

Karen H. Gaines, Biology, University of New Mexico, MSC03-2020, Albuquerque, NM 87131

Island biogeography theory predicts that larger habitat patches will support higher numbers of species.  Unfortunately, studies that explicitly compare diversity patterns exhibited by multiple life stages of a single taxonomic group are uncommon, despite their potential to offer additional insight into the general applicability of this theory.  Dragonflies may represent an ideal group for such a study because these insects experience dramatic changes in environmental requirements and dispersal abilities during the maturation process from aquatic larva to terrestrial adult.  The effects of water quality and physical habitat parameters on adult and larval dragonfly species diversity in a desert sinkhole complex over the course of three years were investigated, and as predicted by island biogeography theory, the species diversity of both life stages increased with increasing sinkhole surface area.  However, the slopes of the respective species-area curves suggest that the sinkhole complex functions primarily as a mainland landscape for volant adult dragonflies and as an island system for larval dragonflies. Sinkhole water salinity had more influence on species diversity than did surface area for each life stage, perhaps because salinity strongly affects other site selection cues used by adult dragonflies and the ability of larvae to survive until emergence.