A female-biased sex ratio reduces the twofold cost of sex.
A female-biased sex ratio reduces the twofold cost of sex.
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DOI：
10.1038/srep23982
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发表时间：
2016-04-01
影响因子：
4.6
通讯作者：
Hasegawa E
中科院分区：
文献类型：
--
作者：
Kobayashi K;Hasegawa E
有性繁殖的进化在生物学上仍然是一个迷人的谜团。从理论上讲，将一半的资源投入到生产无助于生殖的雄性后代的有性有机体种群的增长率应该只有无性生物种群的一半。这种由于男性生育而造成的人口劣势被称为性行为的双重成本。然而，对于性女性来说，这一代价是否真的是双重的这个问题仍然没有答案。当雄性后代的数量减少时，生产雄性的成本应该会降低。在这里，我们报告了一个案例，男性的成本实际上不到两倍。通过测量有性品系与无性品系共存的数量，我们的调查表明，有性品系表现出以雌性为主的性别比例，有性品系的相对频率与有性品系中雄性品系的比例呈负相关。通过计算机模拟，我们证实，由于无性恋个体的共存，性别偏向性别比在有性个体中进化。我们的结果表明，产生雄性的成本取决于雄性的数量。因此，我们得出结论，有性繁殖的进化可能带来的好处比之前假设的要少得多。
The evolution of sexual reproduction remains a fascinating enigma in biology. Theoretically, populations of sexual organisms investing half of their resources into producing male offspring that don’t contribute to reproduction should grow at only half the rate of their asexual counterparts. This demographic disadvantage due to male production is known as the twofold cost of sex. However, the question of whether this cost is truly twofold for sexual females remains unanswered. The cost of producing males should decrease when the number of male offspring is reduced. Here, we report a case where the cost of males is actually less than twofold. By measuring the numbers of sexual strain coexisting with asexual strain among thrips, our survey revealed that the sexual strain showed female-biased sex ratios and that the relative frequency of sexual strain is negatively correlated with the proportion of males in the sexual strain. Using computer simulations, we confirmed that a female-biased sex ratio evolves in sexual individuals due to the coexistence of asexual individuals. Our results demonstrate that there is a cost of producing males that depends on the number of males. We therefore conclude that sexual reproduction can evolve with far fewer benefits than previously assumed.