Stabilized morphological evolution of spiders despite mosaic changes in foraging ecology

A prominent question in animal research is how the evolution of morphology and ecology interact in the generation of phenotypic diversity. Spiders are some of the most abundant arthropod predators in terrestrial ecosystems and exhibit a diversity of foraging styles. It remains unclear how spider body size and proportions relate to foraging style, and if the use of webs as prey capture devices correlates with changes in body characteristics. Here we present the most extensive dataset to date of morphometric and ecological traits in spiders. We used this dataset to estimate the change in spider body sizes and shapes over deep time and to test if and how spider phenotypes are correlated with their behavioural ecology. We found that phylogenetic variation of most traits best fitted an Ornstein-Uhlenbeck model, which is a model of stabilizing selection. A prominent exception was body length, whose evolutionary dynamics were best explained with a Brownian Motion (free trait diffusion) model. ...