关键词: 内脏器官, 消化道, 表型可塑性, 性别, 季节, 长爪沙鼠

Abstract: Both visceral organ mass and digestive tract length show phenotypic plasticity in small mammals,which in turn
is related to their living environmental conditions. To further understand the seasonal adaptive strategy for wild Mongolian gerbils (Meriones unguiculatus),we measured the sexual and seasonal variations of the body mass,masses of visceral organs and digestive organs,as well as the length of each portion of the gut from July 2004 to May 2005 at Taipusiqi County, Nei Mongol,China. All specimens were measured 1 - 3 days after they were live-trapped. Both body mass and body length for male gerbils were higher than those of females,but average liver mass for male gerbils was lower than that of females, and no sexual variation was found for other organ masses. For both the sexes,body mass and heart mass was highest in winter, and lowest in summer. For male gerbils,liver mass was higher in summer,and lowest in spring and winter,but no seasonal variation was found in female gerbils. The average testes mass was highest in spring. The mass of both the caecum and small intestine was higher in autumn than in spring,but no seasonal differences were found among other seasons. Average mass of both the stomach and large intestine did not show any seasonal variation. The length of small intestine was longest in winter and shortest in summer. The length of the caecum was shortest in spring,and the length of the arge intestine was longest in spring and shortest in summer. The plastic variations of body mass,and the respective masses of heart,digestive organs and other visceral organs,as well as the lengths of digestive organs,may play important roles in the adaptation of Mongolian gerbils to changing environments.

Key words: Digestive tract, GendeSeasonr, Internal organ, Mongolian gerbils (Meriones unguiculatus), Phenotypic plasticity, Season