Daphnia invest in sexual reproduction when its relative costs are reduced
Daphnia invest in sexual reproduction when its relative costs are reduced
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DOI：
10.1098/rspb.2017.2176
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发表时间：
2018-01-31
影响因子：
4.7
通讯作者：
Booksmythe, Isobel
中科院分区：
文献类型：
--
作者：
Gerber, Nina;Kokko, Hanna;Booksmythe, Isobel
由于有性生殖与无性生殖在人口统计学上的不同结果，在官能性生物中，性行为的时机对适应性至关重要。除了性本身的代价，性与休眠生命阶段的产生之间的联系也影响了性的最佳利用，特别是在休眠卵对于在不利条件下生存至关重要的环境中。在这里，我们记录的人口动态和发生在自然种群的大型蚤在其生长季节的有性生殖。有性生殖的女性和男性的频率增加人口密度和减少无性窝卵数。随着人口增长率的下降，有性生殖的雌性的频率也增加了。人口动态模型表明，随着人口接近承载能力，有性生殖的机会成本（上述对当前人口增长的贡献）减少，我们发现，在无性生殖的投资是最高的无性人口增长率低或负。我们的研究结果支持了这样的想法，即性的时间与性的相对成本降低时，由于低潜在的无性增长在高人口密度的时期。因此，生态和人口因素的结合影响了有性生殖的最佳时间，使D。magna来平衡性的必要性和成本。
The timing of sex in facultatively sexual organisms is critical to fitness, due to the differing demographic consequences of sexual versus asexual reproduction. In addition to the costs of sex itself, an association of sex with the production of dormant life stages also influences the optimal use of sex, especially in environments where resting eggs are essential to survive unfavourable conditions. Here we document population dynamics and the occurrence of sexual reproduction in natural populations of Daphnia magna across their growing season. The frequency of sexually reproducing females and males increased with population density and with decreasing asexual clutch sizes. The frequency of sexually reproducing females additionally increased as population growth rates decreased. Consistent with population dynamic models showing that the opportunity cost of sexual reproduction (foregoing contribution to current population growth) diminishes as populations approach carrying capacity, we found that investment in sexual reproduction was highest when asexual population growth was low or negative. Our results support the idea that the timing of sex is linked with periods when the relative cost of sex is reduced due to low potential asexual growth at high population densities. Thus, a combination of ecological and demographic factors affect the optimal timing of sexual reproduction, allowing D. magna to balance the necessity of sex against its costs.