黄腹角雉人工种群生存力初步分析
A Preliminary Population Viability Analysis of Cabot’s Tragopan (Tragopan caboti)
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摘要: 黄腹角雉（Tragopan caboti）为我国特有珍稀雉类。目前，其野生种群仅分布于湖南东南部、浙江南部和西南部、江西、福建、广东北部和广西东北部，估计数量约为4000只。湖南省雉类繁殖基地自1997年通过对执法检查中获得的黄腹角雉个体进行收容、救护以及驯养繁殖工作以来，该人工种群已经成功繁殖4年，至2004年年底种群数量为131只。本文利用8年的驯养繁殖过程中获得的种群生态学参数，借助漩涡模型（Vortex9.51）对该种群100年内的动态进行了模拟。结果显示，按照过去8年的生存情况，该种群在100年灭绝的概率为97%。成年雌性的高死亡率和频繁的灾害是影响种群长期存活的两个关键因素。如果成年雌性的死亡率降低到饲养后3年（2002—2004年）时的水平，种群的灭绝概率降低至5%，如果同时控制灾害的发生，其灭绝概率降至0。增加环境容纳量没有降低种群的灭绝概率和增加其增长速度，但增加环境容纳量对100年后的种群数量和基因杂合度有明显的影响。在降低成年雌性死亡率和杜绝灾害发生的情况下，可以考虑对种群进行收获（用作向野外放养），每次收获的数量应该控制在5只成年雄性和5只成年雌，开始收获时间为种群连续繁殖10年以后。降低成年雌性的死亡率、杜绝食物中毒和火灾等灾害的发生以及增加环境容纳量是该人工饲养种群长期存活和发展壮大的重要管理手段。Abstract: The Cabot’s Tragopan, Tragopan caboti, endemic to China, is among one of the critically endangered species globally. It is distributed only in Zhejiang, Fujiang, Jiangxi, Hunan, Guangdong and Guangxi province. There are about 4,000 individuals in the wild but their natural habitat is seriously fragmented. One captive population has been established in Hunan since 1997 by adding new individuals, and its population stood at 131 individuals in 2004. Based on the data collected from this captive population, we used Vortex 9.51 to simulate the dynamics of this population. Results of the simulation suggested that the population has a 97% probability of being extinct under current conditions, within the next 100 years. The high mortality of adult females and the impact of disasters are two key factors which influence the long-term survival of the population. The possibility of extinction will decline to 5% if the mortality of adult females was decreased to the level between 2002 and 2004. And it will decline to 0 if disasters were controlled at the same time. Carrying capacity has positive impacts on the population size and genetic diversity, but has no impact on the extinction probability. Taking individuals out of the wild can only be considered when the mortality of the adult females has decreased and disasters are controlled. Five adult males and five adult females can be taken out of the wild when the population has reproduced after 10 years. To ensure the long-term survival of this captive population, management should focus on decreasing the mortality in adult females, controlling disasters, and increasing the carrying capacity.
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