Is Phenotypic Evolution Affected by Spiders' Construction Behaviors?

This article investigates the role of construction behavior—specifically the building of silk-lined burrows and webs—in shaping the phenotypic evolution of spiders (order Araneae) on a macroevolutionary scale. Using a newly developed set of 99 molecular markers, the authors reconstructed a robust phylogeny of 303 spider species across 105 families and analyzed morphological data from 3,342 extant and 682 fossil species. Their findings indicate that construction behaviors, such as suspending web-building and silk-lined burrowing, have a stronger influence on spider body size and limb morphology than habitat type alone, promoting distinct evolutionary trajectories: silk-lined burrowers tend to have larger bodies with shorter legs and longer patellae, while web-builders exhibit smaller bodies with longer legs and shorter patellae. Additionally, genomic analyses revealed that spiders exhibiting construction behaviors show convergent evolution in genes related to morphogenesis and response to stimuli, supporting the conclusion that construction behavior acts as a significant driver of phenotypic evolution by modifying selective pressures over evolutionary timescales.