Infection dynamics in coexisting sexual and asexual host populations: support for the Red Queen hypothesis

The persistence of sexual reproduction is a classic problem in evolutionary biology. The problem stems from the fact that, all else equal, asexual lineages should rapidly replace coexisting sexual individuals due to the cost of producing males in sexual populations. One possible countervailing advantage to sexual reproduction is that, on average, outcrossed offspring are more resistant than common clones to coevolving parasites, as predicted under the Red Queen hypothesis. In the present study, we evaluated the prevalence of infection by a sterilizing trematode (Microphallus sp.) in a natural population of freshwater snails that was composed of both sexual and asexual individuals (Potamopyrgus antipodarum). More specifically, we compared the frequency of infection in sexual and asexual individuals over a five-year period at four sites at a natural glacial lake (Lake Alexandrina, South Island, New Zealand). We found that at most sites and over most years, the sexual population was less i...

有性生殖的存续问题是进化生物学领域的经典研究课题。该问题的根源在于：在其他条件均一的前提下，由于有性种群需承担产生雄性个体的成本，无性繁殖谱系理应能够快速取代与之共存的有性个体。有性生殖或许存在一种抵消上述劣势的优势：平均而言，异交后代相较于常见克隆个体，对协同进化的寄生虫具有更强的抗性，这一结论符合红皇后假说（Red Queen hypothesis）的预测。本研究针对一个同时包含有性与无性个体的淡水蜗牛自然种群（Potamopyrgus antipodarum），评估了一种可致宿主绝育的吸虫（Microphallus sp.）的感染率。具体而言，我们在五年周期内，对位于新西兰南岛亚历山德里娜湖（Lake Alexandrina）这一天然冰碛湖的四个采样位点，比较了有性与无性个体的感染频率。我们发现，在多数采样位点与多数观测年份中，有性种群的感染率更低……