title: Disturbance by an endemic rodent in an arid shrubland is a habitat filter: effects on plant invasion and taxonomical, functional and phylogenetic community structure.
abstract: Disturbance often drives plant invasion and may modify community assembly. However, little is known about how these modifications of community patterns occur in terms of taxonomic, functional and phylogenetic structure. This study evaluated in an arid shrubland the influence of disturbance by an endemic rodent on community functional divergence and phylogenetic structure as well as on plant invasion. It was expected that disturbance would operate as a habitat filter favouring exotic species with short life cycles.
  
  
  
  Sixteen plots were sampled along a disturbance gradient caused by the endemic fossorial rodent Spalacopus cyanus , measuring community parameters and estimating functional divergence for life history traits (functional dispersion index) and the relative contribution to functional divergence of exotic and native species. The phylogenetic signal (Pagel's lambda) and phylogenetic community structure (mean phylogenetic distance and mean nearest taxon phylogenetic distance) were also estimated. The use of a continuous approach to the disturbance gradient allowed the identification of non-linear relationships between disturbance and community parameters.
  
  
  
  The relationship between disturbance and both species richness and abundance was positive for exotic species and negative for native species. Disturbance modified community composition, and exotic species were associated with more disturbed sites. Disturbance increased trait convergence, which resulted in phylogenetic clustering because traits showed a significant phylogenetic signal. The relative contribution of exotic species to functional divergence increased, while that of natives decreased, with disturbance. Exotic and native species were not phylogenetically distinct.
  
  
  
  Disturbance by rodents in this arid shrubland constitutes a habitat filter over phylogeny-dependent life history traits, leading to phylogenetic clustering, and drives invasion by favouring species with short life cycles. Results can be explained by high phenotypic and phylogenetic resemblance between exotic and native species. The use of continuous gradients when studying the effects of disturbance on community assembly is advocated.
authors.affiliation: Departamento de Biología, Universidad de La Serena, Casilla 554 La Serena, Chile.
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Escobedo
authors.affiliation: Departamento de Biología, Universidad de La Serena, Casilla 554 La Serena, Chile.
authors.forename: Rodrigo S
authors.initials: RS
authors.lastname: Rios
authors.affiliation: Departamento de Biología, Universidad de La Serena, Casilla 554 La Serena, Chile.
authors.forename: Cristian
authors.initials: C
authors.lastname: Salgado-Luarte
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Canada T6G 2E9.
authors.forename: Gisela C
authors.initials: GC
authors.lastname: Stotz
authors.affiliation: Departamento de Biología, Universidad de La Serena, Casilla 554 La Serena, Chile.|Departamento de Botánica, Universidad de Concepción, Casilla 160-C Concepción, Chile.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Gianoli
mesh_terms: D000818:Animals; D044822:Biodiversity; D003889:Desert Climate; D017753:Ecosystem; D058865:Introduced Species; D010802:Phylogeny; D010944:Plants; D011157:Population Dynamics; D012377:Rodentia
keywords: Disturbance gradient; Spalacopus cyanus; exotic species; functional divergence; habitat filtering; phylogenetic signal; phylogenetic structure; short life cycle