title: Stream insect occupancy-frequency patterns and metapopulation structure.
abstract: An understanding of the distribution patterns of organisms and the underlying factors is a fundamental goal of ecology. One commonly applied approach to visualize these is the analysis of occupancy-frequency patterns. We used data sets describing stream insect distributions from different regions of North America to analyze occupancy-frequency patterns and assess the effects of spatial scale, sampling intensity, and taxonomic resolution on these patterns. Distributions were dominated by satellite taxa (those occurring in <or=10% of sites), whereas the occurrence of core taxa (occurring in >or=90% of sites) determined the overall modality of occupancy-frequency patterns. The proportions of satellite taxa increased with spatial scale and showed positive relationships with sampling intensity (r2=0.74-0.96). Furthermore, analyses of data sets from New York (USA) showed that generic-level assessments underestimated the satellite class and occasionally shifted occupancy-frequency distributions from unimodal to bimodal. Our results indicate that, regardless of species- or generic-level taxonomy, stream insect communities are characterized by satellite species and that the proportion of satellite species increases with spatial scale and sampling intensity. Thus, niche-based models of occupancy-frequency patterns better characterize stream insect communities than metapopulation models such as the core-satellite species hypothesis.
authors.affiliation: Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, IL 62901-6501, USA. heatherly75@yahoo.com
authors.forename: T
authors.initials: T
authors.lastname: Heatherly
authors.forename: M R
authors.initials: MR
authors.lastname: Whiles
authors.forename: D J
authors.initials: DJ
authors.lastname: Gibson
authors.forename: S L
authors.initials: SL
authors.lastname: Collins
authors.forename: A D
authors.initials: AD
authors.lastname: Huryn
authors.forename: J K
authors.initials: JK
authors.lastname: Jackson
authors.forename: M A
authors.initials: MA
authors.lastname: Palmer
mesh_terms: D000818:Animals; D003710:Demography; D017753:Ecosystem; D005843:Geography; D007313:Insecta / Q000502:physiology*; D008962:Models, Theoretical; D009656:North America; D010802:Phylogeny; D045483:Rivers