Cognitive performance is linked to survival in free-living African striped mice

Cognition is shaped by evolution and is predicted to increase fitness. However, the link between cognition and fitness in free-living animals is unresolved. We studied the correlates of cognition and survival in a free-living rodent inhabiting an arid environment. We tested 143 striped mice (Rhabdomys pumilio) using a battery of cognitive tests, including: (i) an attention task, (ii) two problem-solving tasks, (iii) a learning and reversal learning task, and (iv) an inhibitory control task. We related cognitive performance with days of survival. Better problem-solving and inhibitory control performance were significant correlates of survival. Surviving males showed greater reversal learning which may be related to sex-specific behavioural and life-history characteristics. Specific cognitive traits and not a composite measure of general intelligence underpins fitness in this free-living rodent population, enhancing our understanding of the evolution of cognition in non-human animals.

Characteristics influencing local enhancement in free-living striped mice

Social learning is widespread across species; however, we still know little about the impact of individual differences in behaviour on social transmission. We aimed to investigate factors influencing social learning in free-living Rhabdomys pumilio, a group-living, arid-adapted mouse. We studied 52 mice in a lid opening task in a field laboratory. We created observer-demonstrator dyads with demonstrators either opening lids or not. We measured success of observers to open lids, their attention and latency to open and time spent interacting with the device. We also considered influences of observer age, sex, group size and personality traits. Demonstrator success did not influence observer success, although attention towards the demonstrator did impact the observers' time spent with the device. Males were more successful than females and more active/explorative observers interacted with the device faster and for a longer time compared to less active/explorative counterparts. We found no influence of age and group size on mouse success. Striped mice appeared to use cues from other individuals to learn how to solve the task and it was influenced by sex and personality. Striped mice in this studied population may use local enhancement to acquire information socially.

Non-random associations in group housed rats (Rattus norvegicus)

Ecological factors, such as predation, have traditionally been used to explain sociability. However, it is increasingly recognised that individuals within a group do not associate randomly, and that these non-random associations can generate fitness advantages. The majority of the empirical evidence on differentiated associations in group-living mammals, however, comes from a limited number of taxa and we still know very little about their occurrence and characteristics in some highly social species, such as rats (Rattus spp.). Here, using network analysis, we quantified association patterns in four groups of male fancy rats. We found that the associations between rats were not randomly distributed and that most individuals had significantly more preferred/avoided associates than expected by random. We also found that these preferences can be stable over time, and that they were not influenced by individuals’ rank position in the dominance hierarchy. Our findings are consistent with work in other mammals, but contrast with the limited evidence available for other rat strains. While further studies in groups with different demographic composition are warranted to confirm our findings, the occurrence of differentiated associations in all male groups of rats have important implications for the management and welfare of captive rat populations.