圈养大熊猫种群性比失衡现象产生机制的探究

Study on the Mechanism of Gender Imbalance in Captive Giant Panda Population

摘要

大熊猫(Ailuropoda melanoleuca)的迁地保护工作已开展了近70年, 基本实现了圈养种群的自我维持。根据2019年大熊猫谱系, 现存圈养大熊猫种群(n=612)的总性比为1.22∶1 (♀336/♂276), 与1∶1的性比有显著性差异(P=0.015), 目前尚未开展性比失衡现象产生机制的探究工作。本研究以全国最大的圈养大熊猫种群为研究对象, 梳理了该种群36年的出生性比、11年的分年龄雌雄个体数量和分年龄死亡雌雄个体数量, 计算了出生性比和预期寿命等数据, 旨在探究性比失衡的内在原因。结果显示, 圈养大熊猫种群的出生性比为1.01∶1, 与1∶1的性比无显著性差异(P=0.926); 雄性大熊猫在幼年阶段死亡的比例高于雌性(♀38.24%/♂48.72%); 圈养大熊猫的出生预期寿命中位数为21.4岁, 其中雌性为23.5岁, 雄性为19.8岁, 雌性预期寿命比雄性长3.7岁。研究表明, 圈养大熊猫种群性比失衡的内在原因是雄性大熊猫幼年阶段的死亡比例高于雌性, 且雌性大熊猫预期寿命更长。本研究聚焦圈养大熊猫种群的性比失衡问题, 首次计算了圈养大熊猫的预期寿命, 可为圈养大熊猫种群的饲养管理和野外大熊猫种群性比问题的进一步研究提供参考。

Abstract

The ex-situ conservation of giant panda (Ailuropoda melanoleuca) has been carried out for nearly 70 years. Nowadays, the captive population is genetically healthy and basically self-sustaining. According to the 2019 giant panda pedigrees, the total sex ratio of the existing captive giant panda population (n=612) is 1.22︰1 (♀336/♂276), which is significantly different from that of 1︰1 (P=0.015). At present, the research on the mechanism of sex ratio imbalance has not been conducted. In this study, the largest captive giant panda population in China was taken as the research object. The data about the population in the sex ratio at birth for 36 years and the numbers of individuals and dead ones by sex and age for 11 years were analyzed. The sex ratio at birth and life expectancy of captive giant panda were calculated for the first time. The results showed that the sex ratio at birth of the biggest captive giant panda population was 1.01︰1, which was not significantly different from the sex ratio of 1︰1 (P=0.926). The mortality rate of male pandas at the early stage was higher than that of female pandas (♀38.24%/♂48.72%). The median life expectancy at birth was 21.4 years, 23.5 years for females and 19.8 years for males. The findings suggested that two reasons were responsible for the gender imbalance of captive giant pandas: the higher mortality rate of male pandas at the early stage and the longer life expectancy of female pandas. The results provide a basis for the breeding and management of captive giant pandas and for research on wild giant panda population in the future.

关键词

大熊猫 / 性比 / 性比失衡 / 预期寿命

Key words

giant panda / sex ratio / gender imbalance / life expectancy