Why Do Some Spiders Cooperate? Agelena consociata, a Case Study

I tested the idea that cooperative behavior develops only in tropical spiders because these species exist in an environment that lacks the pressure of competition for prey. The test species was Agelena consociata, an inhabitant of primary rainforest areas in equatorial Africa. It appears that 1) prey availability is potentially limiting in this environment, 2) extinction rates are higher for small colonies than large ones, 3) the majority of the extinctions occur during the rainy seasons, 4) solitary spiders fail to obtain sufficient prey to rebuild their web traps with the frequency necessitated during two three-month rainy seasons, and finally 5) since web trap sizes are not a linear function of the number of individuals within a colony, by living in groups, individuals of A. consociata can reduce their web maintenance overhead.