The ecology of reproduction in reindeer/caribou (rangifer tarandus) - implications for population dynamics

确定生命史策略变化的模式和原因是生态学的主要目标之一，因为这种变化既塑造了种群动态，反过来又塑造了不同物种的进化生物学。在大量管理的大型食草动物种群中，进化和生态限制与自然种群不同，因为性别比和年龄结构通常是通过收获来操纵的。由此产生的性别比例和年龄结构的倾斜可能会影响生命史策略，特别是与生殖有关的特征；如受胎日期、发情期同步、受胎率、妊娠期长短等影响出生时间和同步性以及出生率和出生体重的参数。本文的目的是研究雄性比例和年龄结构对驯鹿发情期生态的影响及其种群动态的意义。具体而言，我们将研究(a)雄性比例和年龄结构对发情期公母驯鹿体重变化的影响；(b)雄性比例和雄性年龄结构对发情期雌性活动的影响，以及(c)深入了解雄性比例和雄性年龄结构如何影响驯鹿的发情期行为以及受孕和产犊的同步性。这项研究的优势在于它采用了一种实验方法，通过操纵种群中雄性部分的组成，这通常是很难做到的，尤其是在野外的大型哺乳动物中。由于我们解决了理论生态学和管理都感兴趣的问题，因此研究结果将对世界范围内收获的大型食草动物种群的管理产生极大的兴趣。事实上，鉴于全世界大多数有蹄类动物都是采伐的，而且在大多数情况下，优先采伐的是成年雄性动物，这个项目的结果可能有助于制定新的和更适当的管理战略，以维持被操纵的种群的长期生产力。该项目还将有助于训练行为和进化生态学方面的高素质人员。

Determining the patterns and causes of variation in life history strategies is one of the main goals of ecology, as such variations shape both population dynamics and in turn the evolutionary biology of different species. In heavily managed large herbivore populations, evolutionary and ecological constraints are different from natural populations as the sex ratio and age structure is normally manipulated through harvesting. The resulting skews in sex ratio and age structure may have implications for life history strategies and in particular features related to reproduction; such as conception date, synchronization of the rut, conception rate and gestation length - parameters influencing timing and synchrony of birth as well as birth rate and birth weight. My aim is to investigate the role of male percentage and age structure on the ecology of rut in reindeer, and its implication for population dynamics. Specifically, we will examine (a) the influence of male proportion and age structure on the change in body mass of males and females reindeer during rut; (b) the influence of male proportion and male age structure on female activity during rut, and (c) provide insight on how the proportion of males and male age structure influence rutting behaviour and the synchronies of conception and calving in reindeer. The strength of this research resides in its use of an experimental approach by manipulating the composition of the male segment of the population, which is normally difficult to perform especially in large mammals in the wild. Since we address questions that are of interest both for theoretical ecology and management, the results of the study will be of great interest for management of harvested large herbivore populations worldwide. Indeed, given that most ungulate populations are harvested throughout the world and that in most cases, adult males are preferentially harvested, the results of this project may contribute to the development of new and more appropriate management strategies that sustain the long term productivity of the manipulated populations. The project will also contribute to the training of highly qualified personnel in behavioral and evolutionary ecology.