On the origin of bipedal locomotion in rodents (ecological correlates of jerboa's bipedal hopping)

摘要

Biological and behavioral characteristics of Asian jerboas were examined in respect to their degree of specialization for bipedal locomotion based on author's and literary data. Morphological specialization appears to be reflected in the diversity of gaits that jerboas use and in their maximum running speed. Relations between body mass, predominant type of locomotion, diet type and diversity, tactics of danger avoidance and size of home ranges in 20 species of Central Asian jerboas were examined for a latter understanding of the evolution of jerboas as specialized bipeds. There were positive and significant correlations between the diet diversity, maximal speed of locomotion, home range size and species body mass among the jerboa species considered. Results of the stepwise regression analysis performed for 16 jerboa species suggested that maximum running speed was the only important factor in determining the home range size. Maximum running speed appears to be defined by both home range size and species body mass. The latter was the leading parameter in determining the diet diversity in the species. Evolution of bipedality in Asian jerboas seems to be a consequence of inhabiting deserts with poor food reserves and few natural shelters. Under these conditions an extensive type of exploitation of home ranges was formed in parallel with escape from predators using high speed of locomotion. These specific features distinguish the described jerboas from well-studied North American kangaroo rats.