Sex ratio bias, male aggression, and population collapse in lizards
Sex ratio bias, male aggression, and population collapse in lizards
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DOI：
10.1073/pnas.0505172102
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发表时间：
2005-12-13
影响因子：
11.1
通讯作者：
Clobert, J
中科院分区：
文献类型：
--
作者：
Le Galliard, JF;Fitze, PS;Clobert, J
成年人性别比（ASR）是人类和其他动物种群的人口统计学的一个关键参数，但ASR变化的原因，个体如何应对这种变化，以及他们的反应如何反馈到种群动态仍然知之甚少。一个流行的假设是，ASR是由性内竞争，这将导致更多的死亡率或移民的性别增加的频率调节。我们对普通蜥蜴（胎生蜥蜴）种群的实验操作显示了相反的效果。在偏重男性的ASR下，男性死亡率和移民率并不高。相反，过多的成年雄性会引发对成年雌性的攻击，雌性的生存和繁殖能力会随着它们的迁移率沿着下降。随后的预测，成年男性的倾斜应该被放大，总人口规模应该下降，是由长期数据支持。数值预测表明，这种放大效应导致了种群灭绝的重大风险。总的来说，这种走向灭绝的“进化陷阱”威胁着那些雌性需要大量交配成本的种群，环境变化或管理实践使ASR偏向雄性。
The adult sex ratio (ASR) is a key parameter of the demography of human and other animal populations, yet the causes of variation in ASR, how individuals respond to this variation, and how their response feeds back into population dynamics remain poorly understood. A prevalent hypothesis is that ASR is regulated by intrasexual competition, which would cause more mortality or emigration in the sex of increasing frequency. our experimental manipulation of populations of the common lizard (Lacerta vivipara) shows the opposite effect. Male mortality and emigration are not higher under male-biased ASR. Rather, an excess of adult males begets aggression toward adult females, whose survival and fecundity drop, along with their emigration rate. The ensuing prediction that adult male skew should be amplified and total population size should decline is supported by long-term data. Numerical projections show that this amplifying effect causes a major risk of population extinction. in general, such an "evolutionary trap" toward extinction threatens populations in which there is a substantial mating cost for females, and environmental changes or management practices skew the ASR toward males.