Miklós Máté, Laczkó Levente, Sramkó Gábor, Sebestyén Flóra, Barta Zoltán, Tökölyi Jácint
MTA-DE Behavioral Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Hungary.
Juhász-Nagy Pál Doctoral School of Biology and Environmental Sciences, University of Debrecen, Debrecen, Hungary.
Mol Ecol. 2021 Mar;30(5):1206-1222. doi: 10.1111/mec.15810. Epub 2021 Feb 2.
Facultative clonality is associated with complex life cycles where sexual and asexual forms can be exposed to contrasting selection pressures. Facultatively clonal animals often have distinct developmental capabilities that depend on reproductive mode (e.g., negligible senescence and exceptional regeneration ability in asexual individuals, which are lacking in sexual individuals). Understanding how these differences in life history strategies evolved is hampered by limited knowledge of the population structure underlying sexual and asexual forms in nature. Here we studied genetic differentiation of coexisting sexual and asexual Hydra oligactis polyps, a freshwater cnidarian where reproductive mode-dependent life history patterns are observed. We collected asexual and sexual polyps from 13 Central European water bodies and used restriction-site associated DNA sequencing to infer population structure. We detected high relatedness among populations and signs that hydras might spread with resting eggs through zoochory. We found no genetic structure with respect to mode of reproduction (asexual vs. sexual). On the other hand, clear evidence was found for phenotypic plasticity in mode of reproduction, as polyps inferred to be clones differed in reproductive mode. Moreover, we detected two cases of apparent sex change (males and females found within the same clonal lineages) in this species with supposedly stable sexes. Our study describes population genetic structure in Hydra for the first time, highlights the role of phenotypic plasticity in generating patterns of life history variation, and contributes to understanding the evolution of reproductive mode-dependent life history variation in coexisting asexual and sexual forms.
兼性克隆与复杂的生命周期相关，在这种生命周期中，有性和无性形式可能面临截然不同的选择压力。兼性克隆动物通常具有依赖于生殖方式的独特发育能力（例如，无性个体衰老可忽略不计且具有非凡的再生能力，而有性个体则缺乏这些能力）。由于对自然界中有性和无性形式背后的种群结构了解有限，阻碍了我们对这些生活史策略差异如何演化的理解。在这里，我们研究了共存的有性和无性寡柄水螅息肉的遗传分化，寡柄水螅是一种淡水刺胞动物，在其身上可观察到依赖生殖方式的生活史模式。我们从13个中欧水体中采集了无性和有性息肉，并使用限制性位点关联DNA测序来推断种群结构。我们检测到种群之间的高度相关性，以及水螅可能通过动物传播携带休眠卵扩散的迹象。我们没有发现与生殖方式（无性与有性）相关的遗传结构。另一方面，我们发现了生殖方式表型可塑性的明确证据，因为推断为克隆体的息肉在生殖方式上存在差异。此外，在这个性别本应稳定的物种中，我们检测到两例明显的性别变化（在同一克隆谱系中发现雄性和雌性）。我们的研究首次描述了水螅的种群遗传结构，突出了表型可塑性在产生生活史变异模式中的作用，并有助于理解共存的无性和有性形式中依赖生殖方式的生活史变异的演化。
