Mexican Colonial Web-Building Spiders Nest in Colonies That Range in Size

Multiple Choice

Mexican colonial web-building spiders nest in colonies that range in size from ten to thousands of individuals, with each individual occupying their own web within the colony. Colonies are frequently attacked by predatory wasps. Individuals in larger colonies suffer lower predation than those in smaller colonies. The data in the graph below are from a study performed by Uetz et al. (2002) , where they measured the distance at which spiders responded to potential predators. Open bars are for spiders on the interior, and colored bars are for spiders on the periphery of the colony. What type of grouping benefit is demonstrated here?

A) dilution
B) group defense
C) increased vigilance
D) cooperative foraging