甘肃鼢鼠种群年龄的研究

STUDIES ON THE POPULATION AGE OF GANSU ZOKOR

本文根据甘肃鼢鼠(Myospalax cansus)头骨无机盐含量与其已知年龄大小存在的正相关关系,采用头骨干重作为划分该种年龄的指标,并选择体重、体长、头骨颅全长及颧宽检验头骨干重鉴定年龄的可靠性。结果表明:头骨干重是鉴定甘肃鼢鼠年龄的较为准确的可行指标。

From March of 1987 to October of 1988, the authors studied the population ecology of Gansu zokor in Yanan region of north Shaanxi province. Based on a series of experiment for age determination of the Gansu zokor, we found that the contents of inorganic salt in the skull were increasing along with the increasing of age, and there was a positive relation between them. We also found that the dried skull weight were getting heavier when the percentage of the inorganic salts becoming higher. According to above facts, we took the dried skull weight as a major index of age determination, refering to the morphological characters of the skull and the reproduction, as well as the results of observing feeding the zokors in laboratory, the zokor was divided into five age groups through the frequency distribution of the dried skull weight. T-test show that the difference between the skull weight of neighbour two age groups were striking, so the age groups divided by the dried skull weight were trustworthy. There were seasonal and yearly changes in the population age composition. The proportion of the young group was higher than in other seasons, during the breeding seasons. The proportion of subadults was also increasing after the breeding seasons. Because of the generation overlapping, the seasonal variation of proportion in adult group Ⅰ and old group was not obvious. On the other hand, as the differences of temperature and precipitation, the population age composition had yearly changes too. For example, since the low pregnancy rate caused by. the reduce. of precipitation in May of 1988, proportion of the young zokor was lower in 1988 than in 1987.