Spider nest-retreat origin, diversification, and architectural plasticity link to historical and current temperature fluctuations

Ongoing climate change mandates improved understanding of how temperature fluctuations influence organismal evolution and behavior. Detritus-based nest-retreats in spiders have originated multiple times in parallel-hypothesized to be an adaptive response to climatic fluctuations. We investigated the potential role of climate change in shaping the evolution of nest-retreats over geological timescales, and the short-term effect of temperature on the morphology and energy investment of nest-retreats in Campanicola campanulata (Theridiidae). Phylogenetic analyses reconstruct twelve origins of nest-retreats, first appearing in the Eocene, and diversifying during the Late Cenozoic Icehouse period. Spiders respond to experimentally lowered temperatures by making larger nest-retreats, indicating a direct impact of temperature on retreat architecture. Our results for the first time affirm the thermoregulatory function of spider nests and suggest that temperature impacts nest-retreats across both evolutionary and ecological timescales. Nest-retreat spiders can serve as a model to study the origins of thermoregulatory nest-building in animals and how it may be impacted by ongoing climate change.