Adaptation to the temporal environment: evolutionary ecology of mammalian phenologies

从环境中获得的能量必须超过在获取过程中所消耗的能量。任何能产生更大能量盈余的特征，都将允许更多的分配给生存和/或繁殖，因此，代表一种适应。通过这种方式，物候（即每年生活史事件的时间）可以被视为对时间环境的适应。对鸟类和哺乳动物来说，在能量消耗大的事件（如繁殖）和资源丰富的时期之间实现适当的同步尤其重要。恒温动物使这些物种能够在地球上一些最寒冷的地区定居，但这需要大量的能量消耗。因此，轻微的异步将产生严重的能量（因此，健康）后果。几个世纪以来，鸟类物候学吸引了科学界和公众的兴趣，而我们对哺乳动物物候学的了解相对较差。我建议在三个强大的野生哺乳动物研究系统中研究物候变化。红松鼠（Tamiasciurus hudsonicus）和哥伦比亚地松鼠（Urocitellus columbianus）大小相似，系统发育相关，在加拿大西部有重叠的活动范围。然而，红松鼠全年都很活跃，而哥伦比亚地松鼠冬眠8-9个月。自20世纪80年代末以来，在育空西南部（红松鼠）和阿尔伯塔西南部（哥伦比亚地松鼠）进行了全面普查和纯种种群的研究。随后从数千个个体中获得了完整的生活史数据（包括物候记录）。黑尾草原土拨鼠（Cynomys ludovicianus）提供了研究一个物种内部类似程度的变异的机会，就像在上面两个物种中看到的那样。虽然它们的大部分活动范围全年都很活跃，但它们在萨斯喀彻温省南部的北部边缘冬眠。我建议研究从冬眠过渡到冬季活动的种群。有了这三个系统，我将在未来五年实现三个核心目标。首先，物候研究通常集中在繁殖初期的单一性状上。然而，生态和生理关联（例如，分别为携带效应和生物钟）和遗传相关性将直接影响物候性状的当前表达及其未来的进化轨迹。因此，我将研究物候性状全序列（co）变异的原因（遗传和环境）和后果（个体适合度和群体生存能力）。其次，能量的最佳分配包括在竞争需求（维持、生长和繁殖）和时间（一年之内和一生）之间的适当分配。我将利用完整的生活史数据集来研究物候特征的变化如何与其他生活史特征的变化相关联。最后，物候变化是对气候变化最常见的生态反应。在产生这些转变时，表型可塑性和微进化的相对影响将影响它们的速度和持续能力。我将使用定量遗传推断和实验（互惠易位）的结合来解开这两个过程所扮演的相对角色。这一系列互补的目标，运用在三个非常强大的研究系统中，将使我在实现我的长期目标方面取得长足的进步——更好地理解物候学作为生活史变化的基本轴，提高预测气候变化将如何影响野生种群的能力。

Energy acquired from the environment must exceed that which is expended in its acquisition. Any trait that yields a greater energy surplus will permit greater allocation to survival and/or reproduction and, hence, represent an adaptation. In this way, phenologies (i.e., timing of annual life history events) can be viewed as adaptations to the temporal environment. Achieving proper synchrony between energetically expensive events (e.g., reproduction) and periods of resource abundance is especially consequential for birds and mammals. Endothermy has enabled these taxa to colonize some of the coldest areas on the globe, but it entails substantial energetic costs. Slight asynchrony will thus have severe energetic (and thus, fitness) consequences. While avian phenologies have attracted scientific and public interest for centuries, our understanding of mammalian phenologies is comparatively poor. I propose to investigate phenological variation in three powerful wild mammal study systems. Red squirrels (Tamiasciurus hudsonicus) and Columbian ground squirrels (Urocitellus columbianus) are similar in size, phylogenetically related and have overlapping ranges in western Canada. However, whereas red squirrels are active year-round, Columbian ground squirrels hibernate for 8-9 months. Fully censused and pedigreed populations have been studied in the southwest Yukon since the late 1980's (red squirrels) and in southwest Alberta since the early 1990's (Columbian ground squirrels). Complete life history data (including phenological records) have subsequently been obtained from thousands of individuals. Black-tailed prairie dogs (Cynomys ludovicianus) present the opportunity to study a similar degree of variation within one species as seen across the above two. While populations throughout most of their range are active year-round, they hibernate at the northern edge in southern Saskatchewan. I propose to study populations across the transition from hibernating to winter-active. With these three systems, I will meet three core objectives over the next five years. First, phenological investigations typically focus on single traits during the initiation of reproduction. Ecological and physiological associations (e.g., carry-over effects and circannual clocks, respectively) and genetic correlations, however, will directly influence both the current expression of phenological traits and their future evolutionary trajectories. I will thus investigate the causes (genetic and environmental) and consequences (for individual fitness and population viability) of (co)variation in the full sequence of phenological traits. Second, optimal allocation of energy involves appropriate distribution both across competing demands (maintenance, growth and reproduction) and time (within a year and over a lifetime). I will take advantage of the complete life history datasets to investigate how variation in phenological traits correlates with variation in other life history traits. Lastly, phenological shifts are the most commonly reported ecological response to climate change. The relative influences of phenotypic plasticity and microevolution in producing these shifts will influence both their rate and ability to be sustained. I will use a combination of quantitative genetic inference and experimentation (reciprocal translocation) to disentangle the relative roles played by these two processes. This series of complementary objectives, employed within three exceptionally powerful study systems, will enable me to make great strides in meeting my long-term objectives - to gain a better appreciation of phenology as a fundamental axis of life history variation and an improved ability to predict how climate change will affect wild populations.