Scaling of the extended phenotype: convergent energetics from diverse spider web geometries.

Web-building spiders rely on extended phenotypes in the form of silk webs to capture energy. Webs tend to be phylogenetically constrained composite traits, being two-dimensional, typically in the shape of orbs in some spider families, or three-dimensional, in the shape of a tangle or a sheet-and-tangle, in others. We show that the mass-specific prey-capture surface area of webs with different geometries scales in taxon-specific ways with spider body size, including hollowing of sheet-and-tangle webs to maintain isometry.

The mass-specific energy consumption rate, however, scaled hypometrically with identical slopes and intercepts across all three web geometries. Although an allometric relationship between energy acquisition and body size has been shown repeatedly across metazoans, no previous studies have shown such a relationship mediated by a diverse set of extended phenotypes. Our findings support the most general trend predicted by metabolic theory while illustrating how the extended phenotypes spiders build meet their bodies’ energetic demands in diverse ways.

Usage notes

This dataset contains the data (i.e., Trait_data.csv, Bodylength_data.csv, and Wheeler.tre) and code (i.e., Whole_analysis_models_1-2.R, Whole_analysis_models_4-9.R, Ratio_analysis_models_1-2.R, Ratio_analysis_models_4-9.R, PGLS_analysis_model_3.R, and BodyLength_analysis.R) used to generate the results and figures for the paper titled ‘Scaling of the extended phenotype: convergent energetics from diverse spider web geometries’.

The files Ratio_analysis_models_1-2.R, Ratio_analysis_models_4-9.R, PGLS_analysis_model_3.R, and BodyLength_analysis.R contain the code used to generate the graphs featured in the paper. The definitions for all columns (including units) for Trait_data.csv and Bodylength_data.csv are included in the ReadMe file. The Wheeler.tre file is used to create the phylogenetic tree used in the PGLS analysis.

All analyses and graphs were done in R version 4.0.2.