Genomic and Fitness Consequences of Genetic Rescue in Wild Populations
Genomic and Fitness Consequences of Genetic Rescue in Wild Populations
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DOI：
10.1016/j.cub.2019.11.062
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发表时间：
2020-02-03
期刊：
影响因子：
9.2
通讯作者：
Funk, W. Chris
中科院分区：
文献类型：
--
作者：
Fitzpatrick, Sarah W.;Bradburd, Gideon S.;Funk, W. Chris
基因流动是一种神秘的进化力量，因为它可以限制适应性，但也可能拯救小种群免受近亲繁殖衰退[1-3]。基因拯救的几个标志性例子——由基因流动引起的种群增长[4,5]——已经扭转了种群下降[6,7]。然而，对远交抑制和不适应基因流的担忧限制了人类介导的基因流在保护中的应用[8,9]。通过人口和/或遗传机制的移民救援效应已经得到了理论和经验的支持，但缺乏监测基因流动对野生个体和种群的初始和长期影响的研究。在这里，我们使用基于个体的标记重新捕获，多代谱系和基因组学来测试操纵两个孤立的特立尼达野生孔雀鱼种群的基因流动的人口统计学和进化结果。接收种群和源种群来自具有不同捕食、流动和资源制度的环境[10]。我们记录了随着基因流动，种群规模增加了10倍，并发现，平均而言，杂种比本地居民和移民活得更长，繁殖更多。尽管整体基因组均质化，但可能与局部适应相关的等位基因并未完全被基因流淹没。我们的研究结果表明，遗传拯救不仅仅是由个体遗传多样性的增加引起的，而是来自移民的新基因组变异与来自受体群体的等位基因相结合，导致了高度适合的杂交后代和随后的群体规模的增加。与传统的不适应基因流动的观点相反，我们的研究揭示了移民可以在不完全淹没适应变异的情况下在小群体中产生长期适应性利益的条件。
Gene flow is an enigmatic evolutionary force because it can limit adaptation but may also rescue small populations from inbreeding depression [1-3]. Several iconic examples of genetic rescue-increased population growth caused by gene flow [4, 5]-have reversed population declines [6, 7]. However, concerns about outbreeding depression and maladaptive gene flow limit the use of human-mediated gene flow in conservation [8, 9]. Rescue effects of immigration through demographic and/or genetic mechanisms have received theoretical and empirical support, but studies that monitor initial and long-term effects of gene flow on individuals and populations in the wild are lacking. Here, we used individual-based mark-recapture, multigenerational pedigrees, and genomics to test the demographic and evolutionary consequences of manipulating gene flow in two isolated, wild Trinidadian guppy populations. Recipient and source populations originated from environments with different predation, flow, and resource regimes [10]. We documented 10-fold increases in population size following gene flow and found that, on average, hybrids lived longer and reproduced more than residents and immigrants. Despite overall genomic homogenization, alleles potentially associated with local adaptation were not entirely swamped by gene flow. Our results suggest that genetic rescue was caused not just by increasing individual genetic diversity, rather new genomic variation from immigrants combined with alleles from the recipient population resulted in highly fit hybrids and subsequent increases in population size. Contrary to the classic view of maladaptive gene flow, our study reveals conditions under which immigration can produce long-term fitness benefits in small populations without entirely swamping adaptive variation.