黑斑侧褶蛙消化道重量及长度的性别和季节差异

Sexual and Seasonal Differences of Digestive Tract Mass and Length in Pelophylax nigromaculata

消化道是联系脊椎动物能量摄入和能量支出之间关系的纽带,其重量和长度对外界环境具有高度的敏感性和弹性(flexibility)。以黑斑侧褶蛙(Pelophylax nigromaculata)为研究对象,测定了山东聊城地区2012年夏季(16只,8♀/8♂)、秋季(19只,9♀/10♂)及翌年春季(17只,8♀/9♂)其体重、体长、胴体湿重和干重系数、总消化道及各段(食道、胃、小肠和大肠)的湿重、干重和长度系数的性别和季节差异(双因素方差分析),对有性别差异的指标,用单因素方差分析分别比较了雌、雄蛙的季节差异。结果显示,1)雌蛙的体重、体长均高于雄蛙,都在秋季最高,春季或夏季最低;雄蛙的胴体湿重系数高于雌蛙,夏季高于秋季;胴体干重系数既无性别差异,也无季节差异。2)除食道湿重系数无性别差异外,雌蛙总消化道及各段的湿重系数均高于雄蛙;除胃湿重系数无季节差异外,春季或秋季的总消化道及各段的湿重系数都高于夏季;雌蛙的总消化道干重和胃干重系数高于雄蛙,食道、小肠和大肠的干重系数无性别差异,所有的干重系数均无季节性差异。3)除雌蛙的大肠长系数高于雄蛙外,总消化道及各段的长度系数均无性别差异,春季和秋季的总消化道长、食道长及胃长系数均高于夏季,小肠长和大肠长系数均无季节性差异。结果表明,随着季节更替,黑斑侧褶蛙消化道各段的重量和长度表现出一定的弹性特征,这与各器官的功能及其生活环境的多样性是相适应的。

The digestive tract represents a functional link between energy intake and energy allocation in vertebrates. Its mass and length are highly sensitive to environmental adaption, and is of flexibility. In this paper, sexual and seasonal differences in body mass, snout-vent length （SVL） , wet and dry carcass mass indices, as well as wet and dry mass indices, and length indices of total digestive tract and different portions （oesophagus, stomach, small intestine, and large intestine） of digestive tract （Two way ANOVA） were measured in black-spotted pond frog Pelophylax nigromaculata captured in summer （8 males, 8 females, n =16） and autumn （10 males, 9 females, n = 19） 2012, and in spring （9 males, 8 females, n = 17） 2013, respectively from Liaocheng city, Shandong province, China. If some indices showed significant sexual differences, seasonal variations of those indices for any gender were further analyzed by one way ANOVA. The results were as follows ： 1 ） Body mass and SVL in females were higher than in males, and both were higher in autumn than in spring or summer for both sexes. Wet carcass mass index in males was higher than in females, and was greater in summer than in autumn for both sexes. No sexual and seasonal differences were found for dry carcass mass index. 2） All the wet mass indices of total digestive tract and different portions of digestive tract except for oesophagus wet mass index in females were higher than in males. All the wet mass indices of total digestive tract and different portions of digestive tract except for the stomach wet mass index in spring or autumn were greater than in summer. Both total digestive tract and stomach dry mass indices in females were higher than in males, but not for the oesophagus, small intestine and large intestine dry mass indices. All the dry mass indices did not show seasonal differences. 3） No sexual differences were found for the length indices of total digestive tract and different portions of digestive tract except that large intestine length index in females was higher than in males. The length indices of total digestive tract, oesophagus and stomach in spring and autumn were higher than in summer, but not for small and large intestine length indices. These results indicate that the mass and length of different portions of digestive tract in Pelophylax nigromaculata change with seasons, and display some flexibility characters, which may be related to the functions of digestive organs and diversities of life environments.