Extended phenotypes can underlie trade-offs: a case of social spiders

Abstract

Extended phenotypes engineered by animals can potentially improve safety and/or foraging. Whether the well-known trade-off between safety and foraging applies for extended phenotypes, and if so, how it is resolved has not been determined. Spiders build elaborate silk structures that serve as traps for their insect prey and often attach silken retreats (nests) to their capture webs. These extended phenotypes of spiders are made of silk that is considered costly since it is made of protein. Using the Indian social spider, Stegodyphus sarasinorum, we examined how simple proximal factors, like colony hunger state and group size, shape trade-offs in collectively built extended phenotypes that offer shelter and food. We found that well-fed colonies showed greater investment in retreat silk than starved colonies. However, the two groups did not differ in their investment in capture webs. Hence, our findings validate the starvation-risk taking hypothesis in an extended phenotypic paradigm by showing that hungry colonies trade-off retreat size for capture web, irrespective of group size.

Repeatability of an extended phenotype: potential causes and consequences of nest variation in the Northern House Wren (Troglodytes aedon aedon)

“…The copyright holder for this preprint this version posted March 13, 2024. ; https://doi.org/10.1101/2024.03.08.584149 doi: bioRxiv preprint bowers. However, despite the clear potential for construction behaviour to benefit the fitness of an individual, trade-offs often occur between investment in the construction process and other behaviours that affect fitness, such as foraging, which can result in negative effects on both the builder (Madden 2002, Bailey et al 2015 and the structure (Ellendula et al 2021, Parthasarathy et al 2022.…”