Adapting to environmental change: driving factors and the persistence of small populations

气候变化和生境破碎化等全球环境变化正在导致种群数量减少和许多物种内部的种群隔离。对于许多种群来说，如果它们不能通过适应性进化或表型可塑性对这些变化做出反应，就有可能灭绝。哪些人群能够适应？人类能够承受多大的环境变化并继续生存下去？应对环境变化的最有力的预测因素是什么？是否会发生充分的适应以保留人口为人类提供的服务？预计有若干关键因素会降低种群对不断变化的环境条件作出反应的能力，包括：(i)种群规模和遗传多样性减少，（ii）表型可塑性减弱，（iii）没有暴露于环境波动或压力的历史，（iv）更高程度的环境变化，以及(v)无法（至少部分地）克服与种群规模小有关的有害近交影响。然而，这些有争议的预测中有许多被接受了，而没有在野生种群中得到很多强有力的测试。我的研究项目代表了对多种因素如何影响脊椎动物种群对环境变化的反应的原始和综合实证调查，特别是：种群规模、遗传变异、种群表达的表型可塑性程度、种群经历的栖息地变异性或环境变化程度，以及通过净化克服近亲繁殖效应的有效性。为了验证理论预测，我的研究团队将对20个鳟鱼种群（居住在纽芬兰的Cape Race）进行创新的、多年的人口统计学、遗传学和基因组学研究，并结合大量的种群移植实验到新的自然环境中。这项拟议的研究将在跨学科、技术熟练、概念和分析能力强的工作环境中培养9名高素质人才（2名博士、2名硕士和5篇本科生研究论文）和一些志愿者。对加拿大和国际社会而言，这项研究产生的总体知识将直接适用于为食物供应和就业保障所依赖的重要社会经济物种（如鲑科鱼）建立有效的管理和保护措施。这将包括促进关于如何在环境评估、气候变化评估、渔业和野生动物管理以及保护方面最好地优先考虑物种内的种群多样性的决策——以及这样做的最具成本效益的工具。

Global environmental changes such as climate change and habitat fragmentation are leading to diminishing population sizes and the isolation of populations within many species. For many populations, extinction is likely if they cannot respond to such changes via adaptive evolution or phenotypic plasticity. Which populations will be able to adapt? How much environmental change can populations withstand and still persist? What are the strongest predictors for responding to environmental change? And will sufficient adaptation occur to retain the services that populations deliver to humankind? A number of key factors are predicted to decrease the ability of populations to respond to changing environmental conditions, including (i) reduced population size and genetic diversity, (ii) diminished phenotypic plasticity, (iii) a history without exposure to environmental fluctuations or stress, (iv) a higher degree of environmental change, and (v) the inability to (at least partially) overcome deleterious inbreeding effects associated with small population size. However, many of these predictions arguably are being accepted without receiving much strong testing in wild populations. My research program represents an original and integrative empirical investigation into how multiple factors affect responses to environmental change in vertebrate populations, specifically: population size, standing genetic variation, the extent of phenotypic plasticity that a population expresses, the extent of habitat variability or environmental change that a population experiences, and the effectiveness of overcoming inbreeding effects through purging. To test theoretical predictions, my research team will extend innovative, multi-year demographic, genetic, and genomic studies of 20 trout populations (inhabiting Cape Race, Newfoundland) in conjunction with a large series of population transplant experiments to new, natural environments. This proposed research will result in the training of nine highly qualified personnel (2PhD, 2MSc and 5 undergraduate student research theses) and a number of volunteers, in an interdisciplinary, technologically proficient and both conceptually- and analytically-strong working environment. For Canada and the international community, the overall knowledge generated from this research will be directly applicable to establishing effective management and conservation practices for socio-economically important species such as salmonids, upon which food supply and job security depend. This will include a facilitation of decision-making regarding how to best prioritize population diversity within species - and the most-cost effective tools for doing so - for environmental assessments, climate change assessments, fisheries and wildlife management, and conservation.