Mechanisms and Functions of Sexual Segregation in Habitat Use

在许多动物中，雄性和雌性可能在其一生中的一些或大部分时间里分开生活，这称为性别隔离。当两性使用环境的不同部分时，可能会发生性别隔离。古希腊神话讲述了一个被称为亚马孙人的民族，她们生活在一个岛屿上。亚马孙人只与男人见面进行贸易和繁殖，并将所有的女儿都留在岛上。虽然这一古老神话中的真实程度值得商榷，但在动物中，栖息地使用的性别差异是常见的，如果我们要保存和保护物种和栖息地，了解这种行为为什么以及如何发生是至关重要的。例如，如果发生性别隔离，可能有必要为雄性和雌性保护不同的栖息地。然而，我们必须理解为什么以及如何发生这种行为才能做到这一点。一段时间以来，科学家们一直试图了解为什么两性在栖息地的使用上存在隔离。在20世纪的S，查尔斯·达尔文思考了为什么马鹿一年中的大部分时间都是分开生活的。近年来，人们提出了许多解释，其中三个可能是重要的。第一种观点基于这样一个事实，即在许多物种中，雄性和雌性受到捕食者攻击的速度不同。雄性可能体型较大，并配备有鹿角等武器，这可能会使它们使用具有更高捕食风险的栖息地。第二种观点认为，男性和女性的营养需求可能不同，例如由于怀孕，这可能导致两性选择不同的栖息地来满足这些营养需求。最后，雄性对雌性的骚扰在动物界很常见，经常对雌性或其后代造成伤害。最后一个想法是，雌性黑猩猩应该在没有雄性个体的情况下栖息，以减少这种骚扰。此前有关性别隔离的研究主要集中在鹿和羊等有蹄动物身上，但由于它们体型庞大，需要游荡的空间很大，科学家们通常只能描述它们的性别隔离模式。相比之下，这项拟议的研究将以加勒比海特立尼达岛上的一种小型淡水鱼“孔雀鱼”作为模型系统，对这些假设进行实验验证。孔雀在不同的溪流中形成了相对较小的种群，它们面临的捕食者数量各不相同。此外，孔雀鱼可以很容易地被饲养在实验室中，这使得它们特别适合于这次调查。我们知道，生活在高度捕食环境中的孔雀鱼按性别隔离风险，雄性孔雀鱼(更容易被捕食)占据被认为更安全的浅水区，这表明捕食风险在推动性别隔离方面很重要。然而，他们从种族隔离中获得的好处仍然不得而知。例如，为什么雌性接受更大的捕食风险？这是为了减少性骚扰，还是因为对食物的竞争减少了？还是两者兼而有之？我们也不知道性别隔离的模式是如何产生的，也不知道为什么一些男性和女性生活在河流的同一部分。它依赖于环境条件吗？男性和女性的数量以及人口密度的差异对此有何影响？我将比较特立尼达河流中生活在不同捕食风险下的10种野生孔雀鱼的性别隔离程度。在每条河流中，我将评估性别隔离的水平，并将其与捕食风险、种群结构和栖息地类型(例如水深)进行比较，以检验从被认为推动性别隔离的主要思想得出的预测。除了观察野外的行为模式外，这项研究还将在实验室观察孔雀鱼的行为，在实验室中可以测量标准环境中的性别隔离水平，并测试被认为是在隔离中驱动性别隔离的因素。

In many animals males and females may live apart for some or most of their lives termed sexual segregation. Sex segregation may occur when the sexes use different parts of their environment. Ancient Greek mythology tells of a nation of female warriors known as the Amazons who lived on an island. The Amazons only met with men to trade and reproduce and kept all daughters on the island. Whilst the degree of truth in this ancient myth is open to debate, in animals sex differences in habitat use are common and understanding why and how this behaviour occurs is essential if we are going to conserve and protect species and habitats. For example, if sex segregation occurs it may be necessary to protect different habitats for males and females. However, we have to understand why and how this behaviour occurs to be able to do this. For some time scientists have tried to understand why the sexes segregate in habitat use. In the 1900's Charles Darwin pondered over why red deer live apart for much of the year. In recent years many explanations have been proposed, of which three are probably important. The first idea hinges on the fact that in many species males and females are attacked at different rates by predators. Males may be larger and be equipped with weapons such as the antlers, which may allow them to use habitats with increased predation risk. The second idea suggests that males and females may differ in their nutritional requirements, for example due to pregnancy, which may lead to the sexes selecting different habitats to meet these nutritional needs. Finally, harassment of females by males is common in the animal kingdom and frequently causes injury to females or their offspring. The final idea suggests that females occupy habitats with no males to reduce this harassment. Previous work on sex segregation has generally focused on hoofed animals such as deer and sheep, but because of their large size and the amount of space they need to roam, scientists have generally been able to do little more than describe patterns of segregation. In contrast the proposed study will experimentally test these hypotheses using a small species of freshwater fish 'guppies' on the island of Trinidad in the Carribean as a model system. Guppies form relatively small populations in different streams that vary in the number of predators they face. Furthermore, guppies can easily be kept in the laboratory, making them particularly suitable for this investigation. We know that guppies living under high predation risk segregate by sex, with male guppies (which are more vulnerable to predation) occupying areas of shallow water, which are thought to be safer from predators, suggesting that predation risk is important in driving sexual segregation. However, the benefits that they gain from segregation remain unknown. For example, why do females accept a greater risk of predation? Is it to reduce sexual harassment or because there is less competition for food? Or is it a combination of the two? We also do not know how patterns of sex segregation arise, or why some males and females live in the same parts of the river. Does it dependent on environmental conditions? How is it affected by differences in the number of males and females and the density of the population? I will compare the degree of sex segregation between 10 populations of wild guppies living under different risks of predation in the rivers of Trinidad. In each river I will assess the levels of sex segregation and compare it to the risk of predation, population structure and habitat type (e.g. water depth) testing predictions from the main ideas thought to drive sex segregation. In addition to observing patterns of behaviour in the wild this study will observe the behaviour of guppies in the laboratory where it is possible to measure the level of sex segregation in a standard environment and test the factors thought to drive sex segregation in isolation.