Prey Size, Social Competition, and the Development of Reproductive Division of Labor in Social Spider Groups

It has been suggested that the cooperatively social spider, Anelosimus eximius, is eusocial. It has overlapping generations and cooperative brood care, and some females in colonies never reproduce. The hypothesis that the reproductive division of labor arises because of social competition over large prey was tested. Groups of sibling females were provided two types of prey that differed primarily in size. The absolute amount of each type of prey provided fell into three categories. The timing of molt to adulthood and subsequent production of egg sacs was monitored. More spiders molted to adulthood on small fruit flies than on larger houseflies, but the spiders that made it to adulthood in the groups fed larger prey grew larger and produced more egg sacs than the adults on fruit flies at all prey levels. These data suggest that the cooperative capture of large prey in natural colonies influences the formation of a dominant-subordinate dichotomy in which dominants are able to monopolize the resources and secure sufficient resources to reproduce. This system may be important to colony survival because it allows some reproduction to take place even at low prey availability. Likewise, it is possible to envisage such a system's being important to the evolution of the more complex reproductive division of labor with fixed reproductive and nonreproductive castes.

[1]  T. Caraco,et al.  Living in groups: is there an optimal group size? , 1984 .

[2]  S. Riechert,et al.  The Ecology of the Cooperative Spider Agelena consociata in Equatorial Africa (Araneae, Agelenidae) , 1986 .

[3]  S. Emlen,et al.  Perspectives in ornithology: Cooperative breeding strategies among birds , 1983 .

[4]  D. Wise.  Effects of an experimental increase in prey abundance upon the reproductive rates of two orb-weaving spider species (Araneae: Araneidae) , 1979, Oecologia.

[5]  T. Christenson.  Behaviour of colonial and solitary spiders of the theridiid species Anelosimus eximius , 1984, Animal Behaviour.

[6]  P. Ward,et al.  Conflict and Cooperation in the Group Feeding of the Social Spider Stegodyphus Mimosarum , 1985 .

[7]  R. Buskirk.  4 – Sociality in the Arachnida , 1981 .

[8]  W. Wickler,et al.  Bionomics and social structure of 'Family Spiders' of the genus Stegodyphus, with special reference to the African species S.dumicola and S.mimosarum (Araneida, Eresidae) , 1988 .

[9]  R. Jeanne.  Evolution of Social Behavior in the Vespidae , 1980 .

[10]  R. Darchen,et al.  SOCIETIES OF SPIDERS COMPARED TO TH E SOCIETIES OF INSECTS , 1986 .

[11]  P. Ward.  Prey Availability Increases Less Quickly Than Nest Size in the Social Spider Stegodyphus Mimosarum , 1986 .

[12]  Leticia Avilés,et al.  Sex-Ratio Bias and Possible Group Selection in the Social Spider Anelosimus eximius , 1986, The American Naturalist.

[13]  S. Riechert.  Spider Fights: A Test of Evolutionary Game Theory , 1986 .

[14]  N. Jaspen.  Applied Nonparametric Statistics , 1979 .

[15]  D. Smith.  Population genetics of Anelosimus eximius (Araneae: Theridiidae) , 1986 .

[16]  G. B. Pollock.  Chapter 13 – SOCIAL COMPETITION UNDER MANDATORY GROUP LIFE , 1988 .

[17]  Craig Packer,et al.  The Evolution of Cooperative Hunting , 1988, The American Naturalist.

[18]  M. West-Eberhard.  Sexual selection, social competition and evolution , 1979 .