Adaptation is one of the most fundamental issues in the studies of organismal evolution. Pancreatic ribonuclease is a very impor- tant digestive enzyme and secreted by the pancreas. Numerous studies have suggested that RNASE1 gene duplication is closely related to the functional adaptation of the digestive system in the intestinal fermentation herbivores. RNASE1 gene thus becomes one of the most important candidate genetic markers to study the molecular mechanism of adaptation of organisms to the feeding ha...