Facultative iteroparity in a semelparous social spider, Stegodyphus dumicola (Araneae: Eresidae)

Organisms can optimize their reproductive success by differential resource allocation. When adult survival is low, investment of all resources into a single reproductive event can be beneficial, favouring a semelparous strategy. In the spider genus Stegodyphus Simon, 1873 (Eresidae), all species are considered semelparous, based on observations of ancestral subsocial species. However, derived social species show task differentiation and helping by non-reproducing females. This could facilitate a facultative iteroparous strategy by providing sufficient resources to meet the threshold for repeated reproduction. We investigated the reproductive behaviour of groups with single breeding females in the cooperative breeding Stegodyphus dumicola Pocock, 1898. We found that mothers can depart from a strictly semelparous lifestyle by producing more than one clutch. The facultative iteroparity in S. dumicola may enhance colony growth and survival, and act as a mechanism to maintain sociality.