EVOLUTIONARY RATES OF PHENOTYPIC INTEGRATION AND DIETARY ECOMORPHOLOGY IN CARNIVORA (MAMMALIA)

Phenotypic integration describes the overall covariance between morphological traits in organismal form, and bears implications for evolutionary phenomena including adaptation, morphological disparity, evolutionary rates, diversification, etc. However, few studies have analyzed evolutionary rates of phenotypic integration. Evolutionary rates of phenotypic integration describe how fast traits reduce or increase correlation/covariance in the presence of extrinsic factors, where rapid environmental change may induce rapid changes to the magnitude of integration, potentially allowing for greater adaptability and evolvability. The focus of this study attempts to estimate rates of phenotypic integration of traits and its impact on dietary ecomorphological rates of evolution in a phylogenetic comparative method context. Using crania and dentition of the mammalian order Carnivora (cats, dogs, weasels, etc.), phenotypic covariance matrices based on 2D geometric morphometric data were used to calculate an integration metric (Relative Standard Deviation of Eigenvalues), in addition to 14 dietary cranial and dental ecomorphology ratios. Dietary ecomorphology metrics were used as a proxy for ecological variables. Evolutionary rate estimation of integration and ecomorphology was performed using Phylogenetic Ridge Regression in the R package RRphylo, estimating evolutionary rates per branch of a phylogenetic tree, treating the integration metric and each ecomorphological ratio (plus body mass) as tip values evolving along the tree. Ordinary Least Squares analyses were performed between rates of integration and rates of each ecomoprhology metric per phylogenetic tree branch, in order to analyze the association between rates of integration and rates of ecomorphology. Rates of eight out of fourteen ecomorphology metrics were positively correlated with rates of integration (p < 0.05). This indicates that an increase in the evolutionary speed at which integration changes leads to an increase in the speed of dietary ecomorphological evolution.