All known vertebrate clones have originated from hybridization events and some have produced distinct evolutionary lineages via hybrid speciation. Amazon mollies (Poecilia formosa) present an excellent study system to investigate how clonal species have adapted to heterogeneous environments because they are the product of a single hybridization event between male sailfin mollies (Poecilia latipinna) and female Atlantic mollies (Poecilia mexicana). Here, we ask whether the hybrid species differs from the combination of its parental species’ genes in its plastic response to different environments. Using a three‐way factorial design, we exposed neonates produced by Amazon mollies and reciprocal F1 hybrid crosses to different thermal (24°C and 29°C) and salinity (0/2, 12, and 20 ppt) regimes. We measured various ontogenetic and life history characteristics across the life span of females. Our major results were as follows: (1) Reaction norms of growth and maturation to temperature and salinity are quite similar between the two hybrid crosses; (2) Amazon molly reaction norms were qualitatively different than the P. latipinna male and P. mexicana female (L×M) hybrids for the ontogenetic variables; (3) Amazon molly reaction norms in reproductive traits were also quite different from L×M hybrids; and (4) The reaction norms of net fertility were very different between Amazon mollies and L×M hybrids. We conclude that best locale for Amazon mollies is not the best locale for hybrids, which suggests that Amazon mollies are not just an unmodified mix of parental genes but instead have adapted to the variable environments in which they are found. Hybridization resulting in asexuality may represent an underappreciated mechanism of speciation because the unlikely events required to produce such hybrids rarely occur and is dependent upon the genetic distance between parental species.

中文翻译：

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你比你父母基因的总和还多吗？克隆脊椎动物及其亲本 F1 杂种的表型可塑性

所有已知的脊椎动物克隆都起源于杂交事件，有些通过杂交物种形成产生了不同的进化谱系。Amazon mollies (Poecilia formosa) 提供了一个很好的研究系统来研究克隆物种如何适应异质环境，因为它们是雄性帆鳍鼹鼠 (Poecilia latipinna) 和雌性大西洋鼢鼠 (Poecilia mexicana) 之间单一杂交事件的产物。在这里，我们询问杂交物种在对不同环境的塑性反应方面是否与其亲本物种基因的组合不同。使用三向因子设计，我们将 Amazon mollies 和互易 F1 杂交杂交产生的新生儿暴露于不同的温度（24°C 和 29°C）和盐度（0/2、12 和 20 ppt）状态。我们测量了女性整个生命周期中的各种个体发育和生活史特征。我们的主要研究结果如下： (1) 两个杂交杂交体的生长和成熟对温度和盐度的反应规范非常相似；(2) Amazon molly 反应规范在个体遗传变量上与 P. latipinna 雄性和 P. mexicana 雌性 (L×M) 杂种有质的不同；(3) Amazon molly 的繁殖性状反应规范也与L×M 杂种有较大差异；(4)亚马逊鼹鼠和L×M杂种的净育性反应范数差异很大。我们得出的结论是，Amazon mollies 的最佳地点并不是混合动力车的最佳地点，这表明亚马逊鼹鼠不仅仅是亲本基因的未修改组合，而是已经适应了发现它们的可变环境。导致无性的杂交可能代表了一种被低估的物种形成机制，因为产生这种杂交所需的不太可能发生的事件很少发生，并且取决于亲本物种之间的遗传距离。