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- Author or Editor: D. Heathfield x
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Community ecologists have become increasingly interested in analyzing the phylogenetic diversity of species assemblages. Species that co-occur in the same habitats often share a common phylogenetic history such that at coarse spatial scales a species assemblage with a locally clustered phylogenetic structure is usually associated with the presence of habitat filtering mechanisms. However, more recently it has been hypothesized that environmental filters act primarily on the relative abundance of species rather than on their simple presences and absences, reducing the species’ probabilities to persist in given environmental conditions. This process may produce a non-random distribution of species abundances in the regional phylogeny even in the absence of a locally clustered phylogenetic structure. In this paper, using data from the urban flora of Brussels (Belgium) we tested for the presence of non-randomness in the distribution of abundances among the species phylogenetic structure. We argue that the observed pattern of low species phylogenetic distinctiveness at increasing species abundances is compatible with environmental filtering processes.
The increasing availability of phylogenetic information facilitates the use of evolutionary methods in community ecology to reveal the importance of evolution in the species assembly process. However, while several methods have been applied to a wide range of communities across different spatial scales with the purpose of detecting non-random phylogenetic patterns, the spatial aspects of phylogenetic community structure have received far less attention. Accordingly, the question for this study is: can point pattern analysis be used for revealing the phylogenetic structure of multi-species assemblages? We introduce a new individual-centered procedure for analyzing the scale-dependent phylogenetic structure of multi-species point patterns based on digitized field data. The method uses nested circular plots with increasing radii drawn around each individual plant and calculates the mean phylogenetic distance between the focal individual and all individuals located in the circular ring delimited by two successive radii. This scale-dependent value is then averaged over all individuals of the same species and the observed mean is compared to a null expectation with permutation procedures. The method detects particular radius values at which the point pattern of a single species exhibits maximum deviation from the expectation towards either phylogenetic aggregation or segregation. Its performance is illustrated using data from a grassland community in Hungary and simulated point patterns. The proposed method can be extended to virtually any distance function for species pairs, such as functional distances.
