Publications

Species may adapt to changing environments by modifying their social behaviors, often forming larger groups under challenging conditions to enhance survival and reproduction. This environmental buffering response, or social buffering, can mitigate the impacts of unfavourable conditions. A key, but understudied, driver of this response is intragenerational social flexibility, which includes behaviors such as individual dispersal decisions. This study explored the prevalence and mechanisms of environmental buffering in Cape ground squirrels (Xerus inauris), a long-lived, arid-adapted, communal breeder. Analyzing 18 years of data on climate, social organization, reproduction, and survival of a single population of ground squirrels, we found that group sizes increased during periods of temperature extremes. Altered group sizes may have resulted from distinct dispersal strategies: female group fission decreased during colder conditions, while male dispersal was delayed during hotter periods. Through delayed male dispersal, intragenerational social flexibility produced group-level benefits as the increased presence of adult males in groups increased per capita female reproduction during hot periods and enhanced the survival of female juveniles during low-rainfall years and female subadults during warmer years. This buffering effect ultimately supported overall group survival and fecundity under challenging climatic conditions. Our findings underscore the role of intragenerational social flexibility as a rapid response mechanism to climatic variability. As climate change intensifies, understanding these adaptive behaviors will be crucial for predicting species resilience and guiding conservation efforts.

Oxidative stress plays a crucial role in mediating life-history processes, where it can compromise survival and reproduction through harmful alterations to DNA, lipids, and proteins. In this study, we investigated oxidative stress in Cape ground squirrels (Xerus inauris), a longer-lived African ground squirrel species with a high reproductive skew and unique life history strategies. We measured oxidative stress as total antioxidant capacity (TAC), total oxidant status (TOS), and an oxidative stress index (OSI) in blood plasma from individuals of approximately known ages. Our results reveal a distinct pattern of decreasing oxidative stress with age, consistent across both sexes. Females exhibited lower OSI and TOS levels than males. Males employing different life-history strategies, namely natal (staying at home), had significantly lower oxidative stress compared to the band (roaming male groups), likely due to variations in metabolic rate, activity, and feeding rates. However, both strategies exhibited reduced oxidative stress with age, though the underlying mechanisms require further investigation. We propose that selection pressures favoring survival contributed to the observed reduction in oxidative stress with age, potentially maximizing lifetime reproductive success in this species.

Over their lifetime, individuals may use different behavioural strategies to maximize their fitness. Some behavioural traits may be consistent among individuals over time (i.e., ‘personality’ traits) resulting in an individual behavioural phenotype with different associated costs and benefits. Understanding how behavioural traits are linked to lifetime fitness requires tracking individuals over their lifetime. Here, we leverage a long-term study on a multi-year living species (maximum lifespan ~ 10 years) to examine how docility (an individual’s reaction to trapping and handling) may contribute to how males are able to maximize their lifetime fitness. Cape ground squirrels are burrowing mammals that live in social groups, and although males lack physical aggression and territoriality, they vary in docility. Males face high predation risk and high reproductive competition and employ either of two reproductive tactics (‘natal’ or ‘band’) which are not associated with different docility personalities. We found that although more docile individuals sired more offspring on an annual basis, docility did not affect an individual’s long-term (lifetime) reproductive output. Survival was not associated with docility or body condition, but annual survival was influenced by rainfall. Our findings suggest that although docility may represent a behavioural strategy to maximize fitness by possibly playing a role in female-male associations or female matechoice, variations in docility within our study population is likely maintained by other environmental drivers. However, individual variations in behaviours may still contribute as part of the ‘tool kit’ individuals use to maximize their lifetime fitness.

Personality may influence social living and the maintenance of alternative reproductive tactics (ARTs). In some species, suppressing aggression may be important for facilitating social living, and different personalities may be linked with different types of social associations. Yet, few studies have examined personality in species with low levels of aggression. In Cape ground squirrels, males have two discrete ARTs. Males either live in family groups (‘natal’) or all-male groups (‘band’) and lack physical aggression and territoriality. We measured docility (during trapping and handling in 2014e2019, Nmales ¼ 275) and activity and exploration (during an open field test in 2015, Nmales ¼ 34) in adult males to determine whether personality contributes to the maintenance of ARTs. We found repeatability in docility (adjusted repeatability ¼ 0.25e0.26) but not in activity or exploration, and docility was not associated with different ARTs. However, docility and ARTs were influenced by abiotic and biotic factors. Males were more docile after their first capture, and older males (longer on-site tenure) tended to be less docile. In years of higher rainfall, there were more band males, suggesting that ARTs may depend on ecological conditions.