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Stage-structured cycles promote genetic diversity in a predator-prey system of Daphnia and algae

机译：阶段结构的循环促进水蚤和藻类的天敌系统的遗传多样性

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摘要

Competition theory predicts that population fluctuations can promote genetic diversity when combined with density-dependent selection. However, this stabilizing mechanism has rarely been tested, and was recently rejected as an explanation for maintaining diversity in natural populations of the freshwater herbivore Daphnia pulex. The primary limitation of competition theory is its failure to account for the alternative types of population cycles that are caused by size- or stage-dependent population vital rates—even though such structure both explains the fluctuating dynamics of many species and may alter the outcome of competition. Here we provide the first experimental test of whether alternative types of cycles affect natural selection in predator-prey systems. Using competing Daphnia genotypes, we show that internally generated, stage-structured cycles substantially reduce the magnitude of selection (thereby contributing to the maintenance of genetic diversity), whereas externally forced cycles show rapid competitive exclusion. The change in selection is ecologically significant, spanning the observed range in natural populations. We argue that structured cycles reduce selection through a combination of stalled juvenile development and stage-specific mortality. This potentially general fitness-equalizing mechanism may reduce the need for strong stabilizing mechanisms to explain the maintenance of genetic diversity in natural systems.
机译：竞争理论预测，与密度依赖性选择结合时，种群波动可促进遗传多样性。然而，这种稳定机制很少经过测试，最近被拒绝作为维持淡水食草动物水蚤（Daphnia pulex）自然种群多样性的一种解释。竞争理论的主要局限性在于它无法解释由大小或阶段决定的种群生命率所引起的其他种群循环类型，尽管这种结构既可以解释许多物种的波动动态，也可以改变种群的结局。竞争。在这里，我们提供了第一个实验测试，表明替代周期的类型是否会影响捕食者－猎物系统中的自然选择。使用竞争性水蚤基因型，我们表明内部产生的阶段结构的循环大大降低了选择的幅度（从而有助于维持遗传多样性），而外部强迫循环则显示出快速竞争排斥。选择的变化具有生态学意义，跨越了自然种群的观察范围。我们认为结构化循环通过停滞的青少年发育和特定阶段死亡率降低了选择。这种潜在的一般健康平衡机制可以减少对解释自然系统中遗传多样性的维持的稳定机制的需求。

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  • 来源
    《Nature》 |2005年第7024期|p.413-417|共5页
  • 作者

    William A. Nelson; Edward McCauley; Frederick J. Wrona;

  • 作者单位

    Ecology Division, University of Calgary, Calgary, Alberta T2N 1N4, Canada;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
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