title: Local and regional factors influence the structure of treehole metacommunities.
abstract: BACKGROUND
  Abiotic and biotic factors in a local habitat may strongly impact the community residing within, but spatially structured metacommunities are also influenced by regional factors such as immigration and colonization. We used three years of monthly treehole census data to evaluate the relative influence of local and regional factors on our study system.
  
  
  RESULTS
  Every species responded to at least one of three local environmental factors measured: water volume, leaf litter mass, and presence of a top predator. Several species were affected by water volume, and a non-exclusive group of species were influenced by leaf litter mass. Relative abundance of Aedes triseriatus was higher in treeholes with higher volumes of water, and relative abundances of three out of six other species were lower in treeholes with higher volumes of water. Leaf litter mass positively affected densities of Aedes triseriatus and relative abundance of several dipteran species. The density of the top predator, Toxorhynchites rutilus, affected the relative abundance of the two most common species, A. triseriatus and Culicoides guttipennis. Treeholes with T. rutilus had an average of two more species than treeholes without T. rutilus. We found little evidence of synchrony between pairs of treeholes, either spatially or temporally. There were high levels of spatial and temporal turnover, and spatial turnover increased with distance between patches.
  
  
  CONCLUSIONS
  The strong effects of water volume, leaf litter mass, and presence of a top predator, along with the high temporal turnover strongly suggest that species presence and density are determined by local factors and changes in those factors over time. Both low water volume and high predator densities can eliminate populations in local patches, and those populations can recolonize patches when rain refills or predators exit treeholes. Population densities of the same species were not matched between pairs of treeholes, suggesting variation in local factors and limited dispersal. Distance effects on spatial turnover also support limitations to dispersal in the metacommunity, and we conclude that the weight of evidence favors a strong influence of local factors relative to regional factors.
authors.affiliation: Biology Department, Davidson College, Davidson, NC, USA. chparadise@davidson.edu
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Paradise
authors.forename: Jarrod D
authors.initials: JD
authors.lastname: Blue
authors.forename: John Q
authors.initials: JQ
authors.lastname: Burkhart
authors.forename: Justin
authors.initials: J
authors.lastname: Goldberg
authors.forename: Lauren
authors.initials: L
authors.lastname: Harshaw
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Hawkins
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kegan
authors.forename: Tyler
authors.initials: T
authors.lastname: Krentz
authors.forename: Leslie
authors.initials: L
authors.lastname: Smith
authors.forename: Shawn
authors.initials: S
authors.lastname: Villalpando
mesh_terms: D000330:Aedes / Q000502:physiology; D000818:Animals; D044822:Biodiversity; D004175:Diptera / Q000502:physiology; D017753:Ecosystem; D004777:Environment; D009657:North Carolina; D011156:Population Density; D011157:Population Dynamics; D011891:Rain; D014197:Trees / Q000502:physiology*