Collective behavior and colony persistence of social spiders depends on their physical environment

J of Evolutionary Biology

et al. 2019

Identifying the traits that foster group survival in contrasting environments is important for understanding local adaptation in social systems. Here, we evaluate the relationship between the aggressiveness of social spider colonies and their persistence along an elevation gradient using the Amazonian spider, Anelosimus eximius. We found that colonies of A. eximius exhibit repeatable differences in their collective aggressiveness (latency to attack prey stimuli) and that colony aggressiveness is linked with persistence in a site‐specific manner. Less aggressive colonies are better able to persist at high‐elevation sites, which lack colony‐sustaining large‐bodied prey, whereas colony aggression was not related to chance of persistence at low‐elevation sites. This suggests that low aggressiveness promotes colony survival in high‐elevation, prey‐poor habitats, perhaps via increased tolerance to resource limitation. These data reveal that the collective phenotypes that relate to colony persistence vary by site, and thus, the path of social evolution in these environments is likely to be affected.

Section: Methodsmentioning

confidence: 99%

Collective aggressiveness limits colony persistence in high‐ but not low‐elevation sites at Amazonian social spiders

J of Evolutionary Biology

et al. 2019

“…This could also contribute to the observed differences in prey capture rates across sites, because colonies at arid sites captured fewer prey. These effects are costly, as collective foraging aggressiveness is associated with colony mass gain and colony persistence in this system (Pinter-Wollman et al 2017, Kamath et al 2018a.…”

Section: Discussionmentioning

confidence: 99%

Predictors of colony extinction vary by habitat type in social spiders

et al. 2019

Behav Ecol Sociobiol

Self Cite

Many animal societies are susceptible to mass mortality events and collapse. Elucidating how environmental pressures determine patterns of collapse is important for understanding how such societies function and evolve. Using the social spider Stegodyphus dumicola, we investigated the environmental drivers of colony extinction along two precipitation gradients across southern Africa, using the Namib and Kalahari deserts versus wetter savanna habitats to the north and east. We deployed experimental colonies (n = 242) along two ~ 800-km transects and returned to assess colony success in the field after 2 months. Specifically, we noted colony extinction events after the 2-month duration and collected environmental data on the correlates of those extinction events (e.g., evidence of ant attacks, no. of prey captured). We found that colony extinction events at desert sites were more frequently associated with attacks by predatory ants as compared with savanna sites, while colony extinctions in wetter savannas sites were more tightly associated with fungal outbreaks. Our findings support the hypothesis that environments vary in the selection pressures that they impose on social organisms, which may explain why different social phenotypes are often favored in each habitat.

“…For the remaining colonies, aggressiveness was only measured once due to logistical constraints. Latency to attack prey is a common measure of foraging aggressiveness in solitary and social spiders (Riechert & Hedrick, 1993, Pruitt et al, 2013, Kralj-Fiser & Schneider, 2012, Kralj-Fiser et al, 2012), and it tightly linked with prey capture success and foraging performance in several species of group-living spiders (Kamath et al, 2018, Pinter-Wollman et al, 2017, Pruitt & Riechert, 2011).…”

Section: Methodsmentioning

confidence: 99%

Collective aggressiveness limits colony persistence in high but not low elevation sites in Amazonian social spiders

et al. 2019

Preprint

4Identifying the traits that foster group survival in contrasting environments is important for 1 5 understanding local adaptation in social systems. Here we evaluate the relationship between the 1 6 aggressiveness of social spider colonies and their persistence along an elevation gradient using 1 7 the Amazonian spider, Anelosimus eximius. We found that colonies of A. eximius exhibit 1 8 repeatable differences in their collective aggressiveness, and that colony aggressiveness is linked 1 9with persistence in a site-specific manner. Less aggressive colonies are better able to persist at 2 0 high-elevation sites, which lack colony-sustaining large-bodied prey, whereas colony aggression 2 1 was not related to chance of persistence at low-elevation sites. This suggests resistance to 2 2 resource limitation through docility promotes colony survival at high elevations. These data 2 3 reveal that the collective phenotypes that relate to colony persistence vary by site, and thus, the 2 4 path of social evolution in these environments is likely to be affected. 2 5