Resource partitioning is not coupled with assortative mating in sympatrically divergent ricefish in a Wallacean ancient lake
Resource partitioning is not coupled with assortative mating in sympatrically divergent ricefish in a Wallacean ancient lake
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DOI：
10.1111/jeb.13874
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发表时间：
2021-06
影响因子：
2.1
通讯作者：
Ryo Kakioka;Nobu Sutra;Hirozumi Kobayashi;Satoshi Ansai;K. Masengi;A. Nagano;N. Okuda;Rieko Tanaka;M. Sato;K. Yamahira
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文献类型：
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作者：
Ryo Kakioka;Nobu Sutra;Hirozumi Kobayashi;Satoshi Ansai;K. Masengi;A. Nagano;N. Okuda;Rieko Tanaka;M. Sato;K. Yamahira
如果没有允许资源分配的生态特征和允许分类交配的生殖特征之间的耦合，共域物种形成被认为是困难的。众所周知，大多数同域物种形成的令人信服的例子都涉及到这种“神奇的特征”。在这项研究中，我们报告了一个没有魔力特征的共域物种形成的可能案例。苏拉威西岛的一个古老的湖泊--波索湖内，有三种大米鱼(稻属)被认为是共生的。对全基因组单核苷酸多态的分析表明，这三个物种在整个湖泊中是相互生殖隔离的。稳定同位素分析表明，这三个物种使用不同的食物来源，这反映了它们在取食形态(鳃和消化道)和取食地点上的差异。野外和实验室观察表明，星云原虫和直角原甲藻共享鹅卵石交配栖息地，它们在卵石上散布受精卵，而黑斑潜蝇从未利用过这一地点，这表明分类交配部分是通过空间隔离实现的。星云金线鱼和正方石鱼较小的粘附性卵可能反映了它们对卵石海滩产卵的适应。实验室交配实验表明，星云金龟子和正方形金龟子之间存在很强的前合子隔离，这可能是通过物种特有的交配舞蹈和婚礼色彩来实现两性的强烈物种识别。综上所述，星云野生稻和正方野生稻的分类交配可能与资源分配无关。我们讨论了这些物种之间的共域物种形成是如何实现的，即使没有神奇的特征。
Sympatric speciation is considered to be difficult without the coupling between ecological traits that allow resource partitioning and reproductive traits that allow assortative mating. Such “magic traits” are known to be involved in most of the compelling examples of sympatric speciation. In this study, we report a possible case of sympatric speciation without magic traits. Three species of ricefish (genus Oryzias) are suggested to have diverged sympatrically within Lake Poso, an ancient lake in Sulawesi. An analysis of genome‐wide single‐nucleotide polymorphisms showed that these three species are reproductively isolated from each other throughout the lake. Stable isotope analyses revealed that the three species use different food resources, which reflect differences in their feeding morphologies (gill rakers and digestive tracts) and feeding sites. Field and laboratory observations showed that O. nebulosus and O. orthognathus share a mating habitat of cobbles, where they scatter fertilized eggs, whereas this site is never used by O. nigrimas, indicating that assortative mating is partly achieved by spatial isolation. The small, less‐adhesive eggs of O. nebulosus and O. orthognathus probably reflect their adaptation to spawning on cobble beaches. Laboratory mating experiments showed strong prezygotic isolation between O. nebulosus and O. orthognathus, which is achieved by strong species recognition presumably by both sexes based on species‐specific mating dances and nuptial coloration. In summary, the assortative mating of O. nebulosus and O. orthognathus is probably not coupled to resource partitioning. We discussed how sympatric speciation among these species might have been achieved even without magic traits.