title: Cross-scale interactions and the distribution-abundance relationship.
abstract: Positive interspecific relationships between local abundance and extent of regional distribution are among the most ubiquitous patterns in ecology. Although multiple hypotheses have been proposed, the mechanisms underlying distribution-abundance (d-a) relationships remain poorly understood. We examined the intra- and interspecific distribution-abundance relationships for a metacommunity of 13 amphibian species sampled for 15 consecutive years. Mean density of larvae in occupied ponds was positively related to number of ponds occupied by species; employing the fraction of ponds uniquely available to each species this same relationship sharply decelerates. The latter relationship suggested that more abundant species inhabited most available habitats annually, whereas rarer species were dispersal limited. We inferred the mechanisms responsible for this pattern based on the dynamics of one species, Pseudacris triseriata, which transitioned between a rare, narrowly distributed species to a common, widely distributed species and then back again. Both transitions were presaged by marked changes in mean local densities driven by climatic effects on habitat quality. We identified threshold densities separating these population regime shifts that differed with landscape configuration. Our data suggest that these transitions were caused by strong cross-scale interactions between local resource/niche processes and larger scale metapopulation processes. The patterns we observed have relevance for understanding the mechanisms of interspecific d-a relationships and critical thresholds associated with habitat fragmentation.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Earl E
authors.initials: EE
authors.lastname: Werner
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Davis
authors.affiliation: School of Forestry & Environmental Studies, Yale University, New Haven, Connecticut, United States of America.
authors.forename: David K
authors.initials: DK
authors.lastname: Skelly
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Rick A
authors.initials: RA
authors.lastname: Relyea
authors.affiliation: Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Benard
authors.affiliation: Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: McCauley
mesh_terms: D000663:Amphibians; D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D005260:Female; D008297:Male; D008824:Michigan; D061005:Ponds; D011156:Population Density; D011157:Population Dynamics; D062211:Spatio-Temporal Analysis