Morphology predicts foraging guild in araneomorphs

With more than 42,000 species currently described, spiders are one of the most diverse and abundant predators in terrestrial environments (Platnick 2011; Cardoso et al. 2011; Foelix 2011) and an integral part of well-functioning ecosystems (Uetz et al. 1999). Despite this, their evolution and ecology are not well understood (Garrison et al. 2016). Here I use an ecomorphological approach to answer broad questions regarding spider functional ecology across diverse foraging guilds of temperate and tropical Araneomorph species. I examined the morphology of 30 families within several clades of Araneomorphs to test whether morphological measurements of the size and shape of the cephalothorax, abdomen, and leg segments can be used to distinguish among spider foraging guilds based on multivariate morphology even after correcting for body size. I found that spiders within the same foraging guild have similar morphologies, despite diverse phylogenetic relatedness. I found that guilds were significantly different from each other based on overall morphology. Discriminant function analyses correctly classified the majority of taxa to guild, especially so for the species-rich Wanderer and Web Builder guilds. Body shape, and the relative lengths of the abdomen and of the femur and patella of the fourth leg were the most important morphological traits in distinguishing groups. These results show that distantly related taxa of spiders within the same functional group are morphologically convergent, suggesting that morphology reflects the fitness landscape of diverse spider groups. This study represents the first taxonomically and ecologically broad application of ecomorphology to the exceptionally diverse Araneomorphs, and suggests that detailed examination of functional morphology within select groups would be productive.