Title:The evolutionary impact of domestication on the palpebral opening of ruminants
Evolution has been a driving factor in the development of life on Earth, and that process still drives the changes in species continuously. Some of these changes have been selected by humans to reach certain aims in terms of production or utilisation to help the human species. Others happen because the environment these animals are in change and they need to adapt to it, whether by developing new traits for their survival, or devolving traits that are no longer necessary. This thesis studies the impact of domestication in ruminants on one of the 5 main senses; vision. Especially, the size of the palpebral fissure that represents the maximum horizontal angle of vision. We decided to study this aspect in domestication specifically because domestication leads to the animals being protected by humans so they can grow and live until they can be useful to the humans that rear them. This security by humans consists of protection against weather, temperature, but mainly predators. We can suppose that the ruminants, in a position where they would not need their vision to look for predators, then said vision, might decrease because being highly developed would be obsolete. To test this hypothesis, I decided to compare the mean palpebral fissure length in between domesticated and wild ruminants. The domestic ruminants chosen were the cattle (Bos taurus), the goat (Capra aegagrus hircus) and the Sheep (Ovis aries), as these ruminants are the most widespread in terms of domestication. During a trip to South Africa, in the Western Cape, I retrieved measures on three species of large wild ruminants; the Sable Antelope (Hippotragus niger), the Roan Antelope (Hippotragus equinus) and the African Buffalo (Syncerus caffer). These species were chosen due to how taxonomically close these species were to the domestic species used, how similar in size they were, and because I had enough animals to examine to make a proper study. The measures were made and recorded with the help of a calliper ruler under light anaesthesia. In the case of small wild ruminants, I went to Japan, in the Nara park south-east of Kyoto, where I could find Sika Deer (Cervus nippon), the measurements were taken using computerized photographic analysis.