Photoperiod influences the development and the expression of personality traits and social behaviour in wild cavies (Cavia aperea)

Abstract

Seasonality influences behaviour, physiology and life history of organisms, and photoperiod is a reliable and influential cue gearing individual adaptation to seasonal changes in the environment. Plastic phenotypic adjustments according to the prevailing season are a widespread, well‐studied phenomenon. Less well known are effects on developmental trajectories of animals born into different seasons. By manipulating the photoperiod during pregnancy and lactation independent of food availability and temperature, we studied if maternal behaviour in the precocial wild cavy (Cavia aperea) responds to this seasonal cue and if maternal behaviour and photoperiod shape offspring development and behaviour. We repeatedly observed mothers before and after birth. We investigated if pups differ in risk‐taking behaviours directly after birth (indicating direct prenatal effects) or only after gaining independence of the mother (indicating delayed prenatal or postnatal effects due to own cue sampling). Furthermore, we tested if different simulated seasons of birth affect social and aggressive behaviour of adult animals. While theoretical predictions according to risk‐taking are quite clear, they are contradictory for social behaviours that are much less well studied. We predicted that animals born into spring photoperiods would be aggressive because of a need to gather enough resources for early reproduction and successfully establishing a territory at least in males. Spring‐born males were more aggressive than autumn‐borns, while females did not differ with respect to season. Spring‐born females, however, lost more body mass when they had to integrate into an established group and autumn‐born females initiated more aggressive interactions. Our data demonstrate flexible and long‐term stable seasonal effects on behaviours that likely affect fitness outcomes under natural conditions.