Document Type

Article

Publication Date

1-1-2003

Abstract

The transfer of organisms among patches is a key process influencing the spatial structure and regional dynamics of a population; yet, detailed experimental studies of animal movement among patches are uncommon. I performed a series of mark-recapture studies to quantify the movement of a planthopper, Prokelisia crocea (Hemiptera: Delphacidae), among discrete patches of its host plant, prairie cordgrass (Spartina pectinata). Results from these dispersal studies were used to predict the natural distributions and to characterize the spatial population structure of P. crocea. Planthopper emigration loss per patch increased linearly with the density of female conspecifics and was nonlinearly related to patch size (small > large > intermediate sized patches). Planthopper spatial spread was diffusive and 2.7 times faster among cordgrass patches in a heterogeneous habitat (patches embedded in nonhost vegetation) than within a homogeneous habitat (pure cordgrass). Immigration by planthoppers was an increasing function of patch size but was independent of patch isolation (at the scale of this study). The natural distribution of planthoppers in a prairie fragment, obtained from a survey of 146 cordgrass patches over five generations, was well predicted from the dispersal experiments. Planthopper densities and patch occupancy rates were positively correlated with patch size (cordgrass patches ≥0.8 ha were continually occupied), but uncorrelated with patch isolation. Based on this survey; the rate of patch extinction was 21% per generation, highest in small and moderately isolated patches, and approximately equal to the recolonization rate per generation. Finally, the dynamics of local patch populations were asynchronous, even for patch pairs < 10 m apart. I conclude that P. crocea exhibits a population structure most closely resembling a mainland-island metapopulation, but with high patch connectivity. Under these circumstances, processes operating within the few mainland patches are probably more important than regional processes (patch extinctions/recolonizations) in influencing population persistence.

Publication Source (Journal or Book title)

Ecology

First Page

1179

Last Page

1188

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