Clade sorting has a greater effect than local adaptation on ecometric patterns in Carnivora
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2017 P. David Polly. Background: Ecometric patterning is the sorting of mean values of functional traits in communities in space through time at continental scales. Ecometric patterns can emerge from intraspecific population-level processes (selection along an environmental gradient), species-level processes (geographic sorting of species based on functional trait differences), or clade-level processes (geographic sorting based on phylogenetically shared traits). We analysed a hind limb ratio related to locomotion in carnivores (Mammalia, Carnivora) to determine (1) whether its ecometric patterning involves intraspecific population-level evolutionary processes; (2) whether ecometric patterning is produced by clade sorting processes; and (3) how ecometric patterns are altered by species turnover during glacial-interglacial cycles. Data: We analysed (1) intraspecific variation in hind limb ratio in five species to evaluate the importance of population-level processes in ecometric patterning; (2) the distributions of ratios within and among communities to evaluate the importance of clade sorting; and (3) the distributions of ratios of seven glacial fossil assemblages to evaluate temporal dynamics in ecometric patterns. We also analysed three-dimensional calcaneum shape to assess the strength of phylogenetic and functional components of hind limb variation. Analytical methods: Geometric morphometrics, phylogenetic comparative methods, and phylogenetic community assembly methods were used to evaluate trait-based clade sorting; RLQ analysis was used to measure the correlation between vegetation openness, spatial scale, species occurrences, phylogeny, and hind limb traits; and trait space was used to analyse turnover between glacial and extant carnivore communities. Results: Population-level selection is either too weak or ineffective to produce hind limb trait gradients within carnivore species; however, clade-level trait-based sorting has a strong impact on community-level trait distributions. RLQ analysis demonstrates that clade membership interacts with hind limb ratios and vegetation openness in carnivore community assembly. Glacial-interglacial cycles produced turnover in faunas and hind limb trait distributions regardless of location or biome.
