PARENT SESSION
Poster Session #47: Dispersal.
Friday, August 10, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
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Dispersal patterns of Chrysochus auratus in a highly fragmented landscape.
St. Pierre, Matthew1, Hendrix, Stephen1, 1
ABSTRACT- Although many species may persist in fragmented landscapes by reliance on metapopulation dynamics, few well studied examples are known. Survival of a species as a metapopulation depends on long-range dispersal for colonization of suitable vacant habitat patches, a phenomenon that is difficult to study because it often requires extensive mark and recapture of individuals. In summer 1999 and 2000, I individually marked over 16,500 goldsmith beetles (Chrysochus auratus Fabricius; Coleoptera: Chrysomelidae), a host-specific herbivore of dogbanes (Apocynum sp.), at twelve habitat patches in 30 km2 highly fragmented landscape of east central Iowa. My goals were to determine the degree of dispersal between host-patches and to identify factors influencing dispersal frequencies and distances. I recorded 33 between-site dispersal events ranging from 36 meters to 4150 meters. Fewer than half of these dispersals were between nearest-neighbor sites. Over 1900 recaptures within sites show dispersal frequencies decrease exponentially with distance. Neither dispersal distances nor patch residency times were significantly correlated with beetle density in the patch. Sexes did not differ in dispersal distances, dispersal frequencies, or patch residency times. I observed no unoccupied habitat patches of greater than 20 ramets in the vicinity of my study area during either year suggesting that suitable vacant habitat patches are rare. I conclude that this beetle species does not rely on metapopulation dynamics in east central Iowa because of its strong dispersal abilities.
KEY WORDS: dispersal, metapopulation, Chrysomelidae, habitat fragmentation