Effects of acute maternal stress induced by predator cues on spatial learning and memory of offspring in the subterranean rodent Ctenomys talarum.

One of the main selection pressures to which animals are exposed in nature is predation, which affects a wide variety of biological traits. When the mother experiences this stressor during pregnancy and/or lactation, behavioral and physiological responses may be triggered in the offspring as well. Thus, in order to broaden and deepen knowledge on the transgenerational effects of predation stress, we evaluated how maternal stress experienced during pregnancy and/or lactation affects the spatial abilities of progeny at the onset of adulthood in the subterranean rodent Ctenomys talarum. The results showed that, contrary to what was observed in other rodent species, maternal exposure to predator cues during pregnancy and lactation did not negatively affect the spatial abilities of the offspring, even registering some minor positive effects. Concomitantly, no effects of predatory cues on physiological parameters associated with stress were observed in the progeny. This difference in results between the present study and previous works on maternal stress highlights the importance of considering the species to be evaluated (strain, age and origin-wild or captive-) and the type of stressor used (artificial or natural, intensity of exposure) in the evaluation of the possible transgenerational effects of maternal stress.

Mounting a specific immune response increases energy expenditure of the subterranean rodent Ctenomys talarum (tuco-tuco): implications for intraspecific and interspecific variation in immunological traits.

It was recently hypothesised that specific induced defences, which require substantial time and resources and are mostly beneficial against repeated infections, are more likely to be favoured in 'slow-living-pace' species. Therefore, understanding how different types of immune defences might vary with life history requires knowledge of the costs and benefits of defence components. Studies that have explored the energetic costs of immunity in vertebrates have done so with a focus primarily on birds and less so on mammals, particularly surface-dwelling rodents. In this study, we evaluated whether an experimental induction of the immune system with a non-pathogenic antigen elevates the energetic expenditure of a subterranean rodent: Ctenomys talarum (tuco-tucos). In both seasons studied, a significant increase in oxygen consumption was verified in immune-challenged tuco-tucos injected with sheep red blood cells (SRBC) compared with control animals. The increase in oxygen consumption 10 days after the exposure to SRBC was lower for female tuco-tucos monitored in the breeding season compared with females in the non-breeding season. Interestingly, antibody titres of female tuco-tucos did not decrease during the breeding season. Our results add new insight into the role of other factors such as basal metabolic rate or degree of parasite exposure besides 'pace of life' in modulating the interspecific immunological variation observed in natural populations of mammals.

DNA fingerprinting reveals polygyny in the subterranean rodent Ctenomys talarum.

DNA fingerprinting was used to characterize patterns of paternity in two populations of Ctenomys talarum from Buenos Aires Province, Argentina. The multilocus probe PV47-2 was used to detect variation in genomic DNA extracted from 12 females, their 32 offspring, and 14 putative sires. For 11 out of 12 litters examined, a single male capable of providing all nonmaternal bands was identified. Within each study population, individual males sired more than one litter, suggesting that C. talarum is polygynous. No evidence of multiple paternity of litters was found. High band-sharing values among females suggest that further research is needed to assess the population genetic structure of this species.