Testing mating systems theory in a polygynous model system: the reindeer/caribou (Rangifer tarandus)

在过去的几十年里，许多模型都试图为交配系统开发一个预测框架。然而，事实证明，量化性别选择和在该领域测试交配系统理论是困难的。我的目标是用一种实验方法来检验交配系统理论的关键预测。我将操纵雌性密度、食物分散度和运作性别比(OSR)，以评估它们如何影响交配群体动态和交配策略。有蹄类是研究交配系统进化的优秀模式系统，因为它们在性别二型性方面具有最高的可变性，而且它们的父系照顾最少，交配系统的可变性很大。我使用的驯鹿(Rangifer Tarandus)来自一个特殊的种群，在那里所有的个体都将安装GPS项圈，并且可以操纵作为我的模型系统。具体地说，我们将测试：(I)平均群体规模、分裂率、融合率和斑块(衡量雌性在空间中聚集的程度)是否随着密度的增加而增加；(Ii)雌性聚集在食物块上，导致集群和分散处理的平均群体规模和斑块比分散处理更高；(Iii)雄性交配策略在集群处理和分散处理之间存在差异，集群处理中的资源保护和分散处理中的垄断是交配策略可塑性的基础；(Iv)斑块与性选择机会之间的相关性是正相关；以及(V)男性攻击性随着OSR的增加而增加，而女性攻击性随着OSR的增加而减少；求偶率随着OSR的增加而降低，这是因为男性与男性之间的竞争加剧。通过使用完全受控的基于GPS的种群，我的研究将严格测试交配系统理论关于驯鹿的关键预测，并表明是否可以通过操纵当地环境将竞争强度降至最低。这项研究显示了密度对雄性交配成功率和种群生产力分布的影响，并提供了长期保护所需的信息，从而具有管理意义。因此，这项工作提供了对人口调节机制的洞察。

Over the past several decades, many models have attempted to develop a predictive framework for mating systems. However, quantifying sexual selection and testing mating systems theory in the field have proven difficult. My aim is to use an experimental approach to test the key predictions of mating systems theory. I will manipulate female density, food dispersion, and operational sex ratio (OSR) to assess how they influence mating group dynamics and mating tactics. Ungulates are excellent model systems to study the evolution of mating systems because they have the highest variability in sexual dimorphism, and because of their minimal paternal care and great variability in mating systems. I use reindeer (Rangifer tarandus) from an exceptional population where all individuals will be fitted GPS collars and manipulation is possible as my model system. Specifically we will test whether : (i) the average group size, the rate of fission, the rate of fusion, and patchiness (a measure of the degree to which females are clumped in space), increase with density; (ii) females aggregate at food patches, leading to higher average group size and patchiness in clumped than dispersed treatments; (iii) males mating strategy differs between the clumped and dispersed treatments, with resource defense in the clumped treatment and monopolization in the dispersed treatment, underlying the plasticity of mating strategies; (iv) the correlation between patchiness and the opportunity for sexual selection is positive; and whether (v) male-male aggression increases with OSR whereas female-female aggression decreases; and courtship rate decreases with OSR, because of increased male-male competition. By using a fully-controlled GPS-based population, my research will rigorously test key predictions of mating systems theory on reindeer and show whether the intensity of competition can be minimized by manipulating the local environment. The research has management implications by showing density-dependent influence on the distribution of male mating success and population productivity, and by providing information necessary for long term conservation. The work, therefore, provides insight into the mechanisms of population regulation.