Is phenotypic evolution affected by spiders’ construction behaviors?

What happens when organisms actively modify their environment? Clarifying
the role of construction behavior on a macroevolutionary scale is crucial
to interpreting phenotypic evolution. Spiders, an extremely successful
group of animals exhibiting a wide variety of functional, morphological,
and behavioral diversity, are ideal candidates to test whether animal
behaviors are related to their phenotypic evolution. Herein, we
reconstructed the phylogenomic relationships of 303 spiders covering 105
families with 99 newly developed molecular markers that universally apply
across Araneae, and explicitly tested the potential link between
construction behavior and somatic evolution based on extensive
morphological data from 3,342 extant species and 682 fossil species. Our
dated molecular phylogeny provides the backbone for analyses, revealing
the behavioral and ecological processes behind these spiders’
morphological adaptations. Evolutionary model analyses showed the
artifacts constructed by spiders, especially the suspending webs, expand
the spider’s ability to inhabit different habitats. These artifacts have
more substantial impacts on their somatic traits than habitats and promote
different trajectories of morphological evolution. Specifically, for
spiders, silk-lined burrowing produced larger bodies, relatively shorter
legs, and longer patellae, while web-building produced smaller bodies,
relatively long legs, and shorter patellae, and hunting promoted an
intermediate morphological size. Molecular convergence analysis showed
that genes related to morphogenesis or response to stimulus and stress are
enriched in spiders with construction behavior. Our study demonstrated
that the construction behavior of an animal plays a crucial role in
determining the direction and intensity of the selection pressure imposed
on it and provides strong evidence that construction behaviors are
associated with phenotypic evolution on macroevolutionary timescales.