Phylogenetic structure of vertebrate communities across the Australian arid zone

Abstract

Aim: To understand the relative importance of ecological and historical factors in structuring terrestrial vertebrate assemblages across the Australian arid zone, and to contrast patterns of community phylogenetic structure at a continental scale. Location: Australia. Methods: We present evidence from six lineages of terrestrial vertebrates (five lizard clades and one clade of marsupial mice) that have diversified in arid and semi-arid Australia across 37 biogeographical regions. Measures of within-lineage community phylogenetic structure and species turnover were computed to examine how patterns differ across the continent and between taxonomic groups. These results were examined in relation to climatic and historical factors, which are thought to play a role in community phylogenetic structure. Analyses using a novel sliding-window approach confirm the generality of processes structuring the assemblages of the Australian arid zone at different spatial scales. Results: Phylogenetic structure differed greatly across taxonomic groups. Although these lineages have radiated within the same biome - the Australian arid zone - they exhibit markedly different community structure at the regional and local levels. Neither current climatic factors nor historical habitat stability resulted in a uniform response across communities. Rather, historical and biogeographical aspects of community composition (i.e. local lineage persistence and diversification histories) appeared to be more important in explaining the variation in phylogenetic structure. While arid-zone assemblages show an overall tendency towards phylogenetic clustering, this pattern was less pronounced at finer spatial scales. Main conclusions: By focusing within different taxonomic groups and between those groups within regions, we show that although the vertebrate lineages we examined exhibited high diversity and low turnover across the arid zone, the underlying phylogenetic structure differs between regions and taxonomic groups, suggesting that taxon-specific histories are more important than habitat stability in determining patterns of phylogenetic community relatedness. © 2013 Blackwell Publishing Ltd.