Body and Digestive Tract Sizes in Small Phytophagous Mammals: Influence of Ecological and Physiological Factors

The question of the size ratio of the body and the digestive tract (DT) in small phytophagous mammals is considered for the example of gerbils (Gerbillidae), a group of rodents that is exceptionally convenient for studying such relationships due to significant differences in the body weight and the morphological homogeneity of the DT. We analyzed the weight ratios of the body size and the DT and the wet weight of the contents and tissues of the DT in six species of gerbils with a tenfold body weight range (on average, 18 to 175 g) coexisting in the Negev Desert: Psammomys obesus, Meriones crassus, Gerbillus pyramidum, Gerbillus allenbyi, Gerbillus dasyurus, and Gerbillus henleyi. In a number of the studied species of small mammals weighing less than 0.5 kg, no linear relationship was found between the body size and the DT. The allometry of the indicators considered is mainly due to environmental and physiological factors.