Mutation load and rapid adaptation favour outcrossing over self-fertilization
Mutation load and rapid adaptation favour outcrossing over self-fertilization
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DOI：
10.1038/nature08496
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发表时间：
2009-11-19
期刊：
影响因子：
64.8
通讯作者：
Phillips, Patrick C.
中科院分区：
文献类型：
--
作者：
Morran, Levi T.;Parmenter, Michelle D.;Phillips, Patrick C.
生物通过异花受精繁殖的趋势是进化生物学中最古老的谜题之一，尽管与自花受精相比有许多缺点。对于许多物种来说，异交进化的主要障碍是雄性(1)的生产成本，即不直接贡献后代从而减少血统长期生殖产出的个体。自交(‘自交’)生物不会产生雄性生物的费用，因此应该比大多数异交生物至少拥有两倍的数量优势(2)。对于自然界中广泛存在的异交现象，尽管存在这种固有的劣势，但有两种相互矛盾的解释，一是避免了自交造成的近亲繁殖衰退(3-5)，二是异交群体更快地适应环境变化的能力(1，6，7)。在这里，我们表明，异交在秀丽线虫种群中受到青睐，无论是在突变率增加的条件下，还是在适应新环境的过程中，都受到实验进化的影响。总体来说，适合度随着异交率的增加而提高。因此，维持异交的每一种标准解释都是正确的，很可能异交是大多数物种的主要繁殖方式，因为它在自然环境中无处不在的生态条件下是有利的。
The tendency of organisms to reproduce by cross-fertilization despite numerous disadvantages relative to self-fertilization is one of the oldest puzzles in evolutionary biology. For many species, the primary obstacle to the evolution of outcrossing is the cost of production of males(1), individuals that do not directly contribute offspring and thus diminish the long-term reproductive output of a lineage. Self-fertilizing ('selfing') organisms do not incur the cost of males and therefore should possess at least a twofold numerical advantage over most outcrossing organisms(2). Two competing explanations for the widespread prevalence of outcrossing in nature despite this inherent disadvantage are the avoidance of inbreeding depression generated by selfing(3-5) and the ability of outcrossing populations to adapt more rapidly to environmental change(1,6,7). Here we show that outcrossing is favoured in populations of Caenorhabditis elegans subject to experimental evolution both under conditions of increased mutation rate and during adaptation to a novel environment. In general, fitness increased with increasing rates of outcrossing. Thus, each of the standard explanations for the maintenance of outcrossing are correct, and it is likely that outcrossing is the predominant mode of reproduction inmost species because it is favoured under ecological conditions that are ubiquitous in natural environments.