四川荥经县赤腹松鼠体重及脏器湿重的性别与季节差异

以2015年1月至12月捕自四川荥经县的310只成体赤腹松鼠(Callosciurus erythraeus,雄鼠174只,雌鼠136只)为研究对象,分析了其体重及7种内脏器官湿重的性别和季节差异,以及妊娠对内脏器官湿重的影响。1)雌、雄鼠的体重无性别和季节差异。2)心湿重雌、雄鼠差异显著,春季雄性大于雌性,夏季相反;肝、脾、肺和肾的湿重均无性别差异。3)肝湿重夏、冬季高于春、秋季;脾湿重秋季高于冬季和春季;肺湿重春季最高,夏季最低;肾湿重冬、春季高于夏季;心湿重雄鼠秋季高于夏、冬季,雌鼠夏、秋季高于冬季;睾丸和子宫湿重都在春季最高,秋季最低。4)妊娠鼠肝、肺和肾湿重均高于未妊娠鼠。结果表明,随着季节更替赤腹松鼠的体重维持稳定,雌、雄鼠心湿重差异显著,且器官湿重表现出了一定的弹性,这可能与雌、雄鼠的繁殖状态及季节性环境的多样性变化有关。

Sex- and Season-Dependent Changes of Body Mass and Organic Wet Mass in Red-bellied Squirrel (Callosciurus erythraeus) from Yingjing County, Sichuan Province

Both visceral organ mass and body mass 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 Red-bellied Squirrel (Callosciurus erythraeus), 174 males and 136 females were captured from January to December 2015, respectively from Yingjing County, Sichuan Province. We measured body mass, wet masses of visceral organs (liver, heart, spleen, lung, kidney, testis, uterus), analyzed the data from different sexes and seasons. Besides, the impact of pregnancy in body mass and wet masses of visceral organs were also analyzed. These indices were analyzed by Two-way ANOVA or ANCOVA. If some indices showed significant sex differences, seasonal variations of those indices for any gender were further analyzed by one-way ANOVA or ANCOVA. The results were as follows: 1) No sex and seasonal differences were found for body mass (Fig. 1a). 2) Sex difference was only observed for wet mass of heart, especially, males showed higher wet mass of heart than females in spring but lower in summer (Fig. 1b). Additionally, there was no sex difference in the other internal organ wet masses. 3) The wet mass of liver in summer and winter was higher than that in spring and autumn (Fig. 2a). The wet mass of spleen in autumn was higher than that in spring and winter (Fig. 2b) .The wet mass of lung showed the highest value in spring and the lowest value in summer (Fig. 2c). The wet mass of kidney in spring and winter was higher than in summer (Fig. 2d). The wet mass of heart in autumn was greater than in summer and winter for males. However, it is higher in summer and autumn than in winter for females (Fig. 1b). The wet masses of testis (Fig. 2e) and uterus (Fig. 2f) showed the highest values in spring and the lowest values in autumn. 4) The wet masses of liver, lung and kidney showed higher values in pregnant individuals than non-pregnant ones (Table 1). These results indicate that only the wet mass of heart has significant sex difference and the difference changes with seasons. All of the internal organs exhibit some flexibility characters with the change of seasons, whereas the body mass holds stabilization. The reason may be related to the reproductive status of male and female squirrels and the diversities of season environments.