Phylogenetic community ecology: integrating community ecology and evolutionary biology

The species composition of a biological community results from the interplay between evolutionary and ecological processes (Ricklefs 1987). It depends on the availability of species in the species pool of the region where the community is located, the dispersal ability of species in the regional species pool that allows them to reach the community and the degree to which the species that have reached the community can tolerate abiotic and biotic conditions in the locality (Willis et al. 2010). However, evolutionary and ecological processes assembling species into biological communities have generally been studied in isolation from one another (Johnson and Stinchcombe 2007). In the face of widespread and various anthropogenic threats to biological communities worldwide, it is urgent to understand how evolutionary and ecological processes interplay to generate and maintain biodiversity patterns and species membership in biological communities across the globe. Species diversity and assembly of biological communities are thought to be driven by three groups of processes: nichebased processes (e.g. Chase and Leibold 2003; Diamond 1975; Tilman 1982; Weiher and Keddy 1999), neutralitybased processes (Bell 2001; Hubbell 2001) and historyrelated processes (Ricklefs 1987; Ricklefs and Schluter 1993). Phylogenies, especially when calibrated with a dimension of time, can illuminate our knowledge of evolutionary histories of biological communities at multiple temporal and spatial scales (Pennington et al. 2006). At a global scale, they permit a re-evaluation of the relative roles of plate tectonics and long-distance dispersal in the assembly of regional and continental biota (Crisp et al. 2004). At a local scale, they permit an examination of phylogenetic relatedness of species and provide insights into the assembly of biological communities (Webb et al. 2002). In particular, as Cavender-Bares et al. (2009) point out, ‘phylogenetics helps to resolve the long-standing controversy about the relative roles of neutral vs. niche-related processes in community assembly and facilitates identification of the kinds of processes that underlie community assembly’. The assembly of local biological communities is thought to be generally driven by two processes: filtering of species that can persist within a community on the basis of their tolerance of the abiotic environment (Weiher and Keddy 1995) and biotic interactions among species that limit their longterm coexistence (Elton 1946; Gause 1934; Leibold 1998). The phylogenetic structure of a community can be assessed by comparing the species composition of the community with that of the regional species pool. Phylogenetic clustering should result when conserved characters determine habitat filtering, because they influence tolerance of abiotic conditions, and phylogenetic overdispersion is expected to occur if there is either filtering on convergent characters or competitive exclusion of species with similarity in conserved characters (Cavender-Bares et al. 2004; Webb et al. 2002), although competitive exclusion may also result in phylogenetic clustering (Mayfield and Levine 2010). If phylogenetic relatedness predicts ecological similarity, phylogenetic diversity should increase ecosystem productivity by maximizing total resource uptake (Pennington et al. 2006). A high degree of phylogenetic signal has been frequently found in plant functional traits (e.g. Donoghue 2008; Moles et al. 2005). Phylogenetic structure within communities can also influence phylogenetic turnover between communities, i.e. phylogenetic beta diversity (Graham and Fine 2008). Since an early attempt to perform a phylogenetic analysis of community structure (Webb 2000), the use of phylogenies to investigate patterns of community structure has blossomed (Fig. 1). This Special Issue includes a collection of 10 research papers in the field of phylogenetic community ecology. These papers cover a wide range of spatial extents from an experiment in laboratory microcosms (Pu et al. 2014) to the globe (Brunbjerg et al. 2014), covering a wide taxonomic spectrum of organisms including microbial bacterivorous ciliated protists (Pu et al. 2014) and vascular plants (all other papers in this issue). Most of the papers investigated phylogenetic structure within biological assemblages, with five papers (i.e. Brunbjerg et al. 2014; González-Caro et al. 2014; Qian et al. 2014; Yang et al. 2014; Zhang et al. 2014) using net relatedness index (NRI) or nearest taxon index (NTI) as a measure of phylogenetic structure. Three papers