Thermal tolerance may cause sexual segregation in sexually dimorphic species living in hot environments
Thermal tolerance may cause sexual segregation in sexually dimorphic species living in hot environments
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DOI：
10.1093/beheco/arv211
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发表时间：
2016-05-01
影响因子：
2.4
通讯作者：
Palacin, Carlos
中科院分区：
文献类型：
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作者：
Alonso, Juan C.;Salgado, Ivan;Palacin, Carlos
在炎热的环境中，许多物种寻求阴凉处，以减少他们在中午的热负荷，热敏感性的性别差异可能会导致不同的模式，在男性和女性的住房使用，构成了性别隔离机制。在生活在这些地区的两性大小二型物种中，较大的雄性在散发体热和减少蒸发水分损失方面有更多的困难。这发生在大鸨（奥蒂斯tarda），最性别大小二型鸟。先前的一项研究表明，繁殖区夏季温度与雄性向北迁移至较冷地区之间存在相关性，这为雄性耐热性低于雌性提供了有力证据。然而，并不是所有的男性迁移，在这里，我们调查的行为适应，帮助久坐的男性抵御夏季炎热。男性表现出更强的依赖植被提供树荫比女性在中午。所有的男性寻找阴凉处后，上午觅食期间，而只有三分之二的女性这样做，进入阴凉处1小时后比男性。男性觅食不那么密集，移动觅食和休息的位置之间的距离较短，飞行比女性少。树荫的使用是观察到的性别差异的主要原因，在夏季微生境的选择，而较低的食物摄入量，减少运动和飞行活动的添加剂影响空间和社会隔离的因素。这些模式可能是强大的适应价值的男性，可以解释为机制，以防止过热在夏季，当男性达到最低体重和最高死亡率值的季节。
In hot environments, where many species seek shade to decrease their heat load at midday, sexual differences in heat sensitivity could lead to different patterns of shelter use in males and females, constituting a sexual segregation mechanism. In sexually size-dimorphic species living in these areas, the larger males have more difficulties in dissipating body heat and reducing evaporative water loss. This occurs in the great bustard (Otis tarda), the most sexually size-dimorphic bird. A previous study showed a correlation between summer temperature at breeding areas and northward migration to cooler areas only in males, providing strong evidence for their lower heat tolerance compared with females. However, not all males migrate, and here, we investigate the behavioral adaptations that help sedentary males to withstand summer heat. Males showed a stronger dependence on vegetation providing shade than females at midday. All males searched for shade after the morning foraging period, whereas only two-thirds of the females did it, entering shade 1 h later than males. Males foraged less intensively, moved shorter distances between foraging and resting locations, and flew less than females. The use of shade is the main cause of the observed sexual differences in microhabitat selection in summer, whereas lower food intake, and reduced locomotor and flight activity represent additive factors affecting spatial and social segregation. These patterns are probably of strong adaptive value for males, and can be interpreted as mechanisms to prevent overheating during summer, the season when males reach lowest body weights and highest mortality values.