Phenotypic plasticity in an extended phenotype: the cobweb spider Campanicola campanulata alters web architecture in response to variation in prey availability

Phenotypic plasticity in extended phenotypes has been proposed as a mechanism by which animals modify their phenotypes in response to changing environmental conditions. This phenomenon is exemplified by certain spiders that construct bell-shaped cobwebs using sand grains, soil particles, prey remains, and plant debris. The retreat and gumfooted lines in these cobwebs are believed to serve defensive and foraging functions. This study aimed to test both the phenotypic plasticity and the trade-off hypotheses by examining whether the common cobweb spider Campanicola campanulata alters web architecture and behavioral investments in response to variations in prey availability. When prey availability increases, spiders build webs higher, construct smaller and lighter retreats, and produce cobwebs with fewer gumfooted lines and smaller capture areas. Results indicated that, in the presence of abundant ant prey, spiders reduced their investment in both foraging and defense. These findings suggest that the web architecture of C. campanulata exhibits a high degree of plasticity in response to variation in prey availability, but investment in web architectures do not involve trade-offs between foraging and defense.