Despite the benefits associated with protection and foraging activities, group living also implies challenges for individuals. The evolutionary transition from subsocial to social living changed the reproductive life histories in many animals. In social species of the spider genus Anelosimus, producing few but large offspring seems to be a strategy to mitigate high competition between spiderlings in multi-matriarch colonies, compared to single-matriarch colonies of subsocial species. However, it is still to be determined how the subsocial species of this genus can benefit themselves from producing larger clutches of relatively small offspring. Large clutches may ensure the subduing of large and/or harmful prey. In addition, many spiderlings may also repair the webs of subsocial spiders efficiently. We hypothesized that colonies individually initiated by large females of Anelosimus jabaquara and by females of other subsocial Anelosimus species present a higher survivorship than those individually initiated by small females of A. jabaquara and by females of social Anelosimus species. We monitored the persistence of the colonies of three Anelosimus species with different sociality levels and female sizes. All the monitored cohorts presented similar rates of persistence. However, all these species presented higher colony persistence than those of more social congener species reported in the literature. We also surveyed the natural enemies that contributed to the colonies’ extinctions, which included predators, parasitoids, and kleptoparasites. These results allowed us to discuss how sociality can affect reproduction and how investing in the number of offspring, rather than the size, can benefit solitary or subsocial Anelosimus species.
Xavier, G.M., Moura, R.R., Sobczak, J.F. et al. Spider colony extinction does not depend on degree of sociality and maternal size in three Anelosimus species (Araneae, Theridiidae). Behav Ecol Sociobiol 79, 1 (2025). https://doi.org/10.1007/s00265-024-03545-5
