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消耗的能量。任何产生更大能量盈余的性状将允许更大的生存和/或繁殖分配，因此代表一种适应。以这种方式，物候（即，年度生活史事件的时间）可以被视为对时间环境的适应。在能量昂贵的事件（例如，繁殖）和资源丰富的时期对鸟类和哺乳动物尤其重要。恒温使这些类群能够在地球仪上最寒冷的地区定居，但这需要大量的能量成本。因此，轻微的肥胖会产生严重的能量（以及健康）后果。虽然鸟类的物候已经吸引了科学和公众的兴趣几个世纪，我们对哺乳动物的物候的理解是比较差的。我建议调查物候变化在三个强大的野生哺乳动物研究系统。红松鼠（Tamiasciurus hudsonicus）和哥伦比亚地松鼠（Urocitellus columbianus）大小相似，在加拿大西部有重叠的分布范围。然而，红松鼠全年都很活跃，而哥伦比亚地松鼠则冬眠8 - 9个月。自20世纪80年代末以来，在育空地区西南部（红松鼠）和自20世纪90年代初以来在阿尔伯塔西南部（哥伦比亚地松鼠）对全面普查和纯种种群进行了研究。完整的生活史数据（包括物候记录），随后获得了成千上万的个人。黑尾草原犬鼠（Cynomys ludovicianus）提供了研究一个物种内类似程度变异的机会，正如在上述两个物种中所看到的那样。虽然它们的大部分分布区全年都很活跃，但它们在萨斯喀彻温省南部的北方边缘冬眠。我建议研究从冬眠到冬季活跃的过渡时期的种群。通过这三个系统，我将在未来五年实现三个核心目标。首先，物候调查通常集中在繁殖开始期间的单一性状。生态和生理协会（例如，遗传相关性将直接影响物候特征的当前表达及其未来的进化轨迹。因此，我将调查原因（遗传和环境）和后果（个人健身和人口的生存能力）的（共同）变化的完整序列的物候特征。其次，能量的最佳分配涉及在相互竞争的需求（维持、生长和繁殖）和时间（一年内和一生）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。最后，物候变化是对气候变化最常见的生态反应。表型可塑性和微进化在产生这些变化方面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理和实验（相互易位）的组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，在三个非常强大的研究系统中使用，将使我能够在实现我的长期目标方面取得重大进展-更好地欣赏物候学作为生活史变异的基本轴，并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.