Chirichella, Roberta (2011) Ecological factors affecting investment in body mass, and horns in the Alpine chamois (Rupicapra rupicapra). Doctoral Thesis.
Fitness in herbivorous polygynous species is related both to body conditions and to secondary sexual traits. Ungulates therefore must balance resources between body size and antlers/horns growth. Here I described how some ecological factors affected the investment in body mass and horn length in Alpine chamois (Rupicapra rupicapra). Chamois horns grow mainly in the first years of life and their size can be deciding for future individual success. Therefore I analyzed the horn size variation in yearlings according to a large set of ecological variables, including for the first time also soil type (calcareous or siliceous). I found that there are many environmental and climatic factors able to modify horn length. Both sexes showed a high investment in horn grow in good conditions but females on siliceous soil and after harsher winter reduced this investment. Moreover I analyzed the reproductive strategy over time in male Alpine chamois and I showed that the reproductive investment increased with age by continuing to invest more energy after prime age. This strategy is in agreement with the terminal investment hypothesis. Finally I investigated which factors negatively affected the free access to resources for this species. I demonstrated for the first time how livestock and a wild non native ungulate (Ovis orientalis musimon) may force chamois to use sub-optimal meadows, negatively affecting the gain of a proper body size during summer due to reduction of feed intake.
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