Factors affecting puberty in male ground squirrels

Age at sexual maturity is an important trait of individual life history strategies. Early puberty can prolong the overall time span for reproduction and thereby increase an individual`s offspring. On the other hand, sexual maturation processes have been proposed to be affected by trade-offs with growth patterns and potential mating success. The strict timing of seasonal activities in hibernating species is an additional constraint in these interactions. Although these trade-offs have been documented in a number of species, the environmental key factors suppressing or activating gonadal development often remain unclear. In free-ranging European ground squirrels (Spermophilus citellus), male puberty has been found to vary with population density. In the proposed project we aim to test factors affecting male puberty in semi-natural conditions and in free-living individuals. Previous studies enabled us to identify some potential parameters, that could delay or accelerate puberty in male ground squirrels and that are known to vary with population density. An experimental setup in semi-natural enclosures would provide a suitable opportunity to test the effects of specific environmental factors on male behavior and physiology. Access to specific nutritional components can be critical for developmental processes and hibernation patterns. We plan to examine two factors, proteins and polyunsaturated fatty acids. Our second approach is to manipulate the social environment of the young males. The presence of potential mates and superior competitors affects maturity in subadult males in many species. Young males will be raised in different social groups to investigate behavioral and/or physiological influences of inter- or intrasexual interactions. This can be carried out in the enclosures and in a field experiment. Finally, hibernation may also play an important role determining male development. Suitable hibernacula are critical resources for over-winter survival, mass loss and perhaps the course of gonadal development. Hibernaculum quality and hibernation patterns will be monitored in all experimental individuals. The potential consequences of early puberty, reflected in growth patterns, stress levels and immune competency will be documented in precocious compared to immature yearlings.

Age at sexual maturity is an important trait of individual life history strategies. Early puberty can prolong the overall time span for reproduction and thereby increase an individual`s offspring. On the other hand, sexual maturation processes have been proposed to be affected by trade-offs with growth patterns and potential mating success. The strict timing of seasonal activities in hibernating species is an additional constraint in these interactions. Although these trade-offs have been documented in a number of species, the environmental key factors suppressing or activating gonadal development often remain unclear. In free-ranging European ground squirrels (Spermophilus citellus), male puberty has been found to vary with population density. In the proposed project we aim to test factors affecting male puberty in semi-natural conditions and in free-living individuals. Previous studies enabled us to identify some potential parameters, that could delay or accelerate puberty in male ground squirrels and that are known to vary with population density. An experimental setup in semi-natural enclosures would provide a suitable opportunity to test the effects of specific environmental factors on male behavior and physiology. Access to specific nutritional components can be critical for developmental processes and hibernation patterns. We plan to examine two factors, proteins and polyunsaturated fatty acids. Our second approach is to manipulate the social environment of the young males. The presence of potential mates and superior competitors affects maturity in subadult males in many species. Young males will be raised in different social groups to investigate behavioral and/or physiological influences of inter- or intrasexual interactions. This can be carried out in the enclosures and in a field experiment. Finally, hibernation may also play an important role determining male development. Suitable hibernacula are critical resources for over-winter survival, mass loss and perhaps the course of gonadal development. Hibernaculum quality and hibernation patterns will be monitored in all experimental individuals. The potential consequences of early puberty, reflected in growth patterns, stress levels and immune competency will be documented in precocious compared to immature yearlings.