Geological Substrate Is Related to Tooth Senescence and Population Dynamic: The Case Study of Alpine Chamois (Rupicapra rupicapra L.).

Abstract

Senescence is defined as a chronological decline in demographic performance with age, showing a gradual deterioration of body functions and a related decline in survival. We analyzed biometric data from over 31 000 Alpine chamois (Rupicapra rupicapra L.) culled during 12 consecutive hunting seasons in 28 hunting districts with different geological substrate (calcareous, metamorphic, and siliceous) in Central-Eastern Alps (Italy). Available data confirmed that females experienced a later senescence than males, in terms of loss in eviscerated body mass. This is in accordance with a greater energy expenditure undergone by males in rut period. Interestingly the different geological substrate influenced the final body mass and the decline of body functions of chamois living in different areas. A pivotal role in this process seems to be played by tooth wear. The progressive wearing of the cheek teeth was assessed in a subset of 596 mandibles using the height of molars and their height/breadth ratio. Referring to the same sex and age, the wear progress on calcareous substrate is slower than the one on other substrates. Indeed, siliceous and metamorphic substrates hold meadows with higher resistance to mechanical stress due to the presence of opal silica and lower nutritional quality compared with calcareous ones. As a consequence, life expectancies and population dynamics depend on the substrate where the chamois population lives. Enhancing knowledge about environmental factors that can affect individual biometrical characters and senescence should be considered a priority to improve adaptive management of hunting species, as well the different distribution of the hunting classes and quotas.