Maternal inheritance of F1 hybrid morphology and colony shape in the coral genus Acropora
Maternal inheritance of F1 hybrid morphology and colony shape in the coral genus Acropora
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DOI：
10.7717/peerj.6429
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发表时间：
2019-02-19
期刊：
影响因子：
2.7
通讯作者：
Isomura, Naoko
中科院分区：
文献类型：
--
作者：
Fukami, Hironobu;Iwao, Kenji;Isomura, Naoko
研究背景：鹿角珊瑚属（Acropora）包括150多个物种，具有非常高的形态多样性。这种高度的多样性可能是由于通过大量产卵重复杂交造成的。然而，我们对这些珊瑚中是否形成杂交体的信息很少。确定杂交种和它们的亲本物种之间的形态差异将提供一个机会，在该领域找到野生杂交种，并了解如何在整个进化历史上的鹿角珊瑚的殖民地形状变得高度多样化。在两种形态特征独特的珊瑚Acropora佛罗里达和A.结果表明，在离体条件下，两种植物的配子体具有很高的双向杂交率，是研究杂种形态特征的理想物种。佛罗里达州到A. intermedia，它们是从离体杂交实验中产生的。为了比较形态学差异，我们培养了正反交F1杂种（FLOint：A.佛罗里达eggs x A. intermedia sperm和INTflo：A. intermedia eggs x A.佛罗里达sperm）和亲本种（A. intermedia和A.佛罗里达州）。我们分析了骨骼形态，如菌落大小，分支长度和分支数，并将它们与A.佛罗里达和A.在田野里发现的中间种。我们还证实了F1杂种，亲本物种，和一个假定的F1杂种使用线粒体非编码区的分子系统发育位置。结果：我们的形态学分析表明，分支数的F1杂种是中间相对于亲本物种。此外，FLOint杂种在形态上更接近于母体物种A。佛罗里达，而INTflo杂种则是A.中间的分子生物学数据表明，A.佛罗里达和A. intermedia明显分为两个分支，杂种F1按母本聚在Glade内。一个非常相似的模式，INTflo杂种获得了假定的F1杂种在nature.Discussion：我们的研究结果表明，F1杂种之间的两个印度-太平洋物种A。佛罗里达和A.中间种的形态相对于其亲种具有中间性，但更能反映母本。在杂种中与母本物种的相似性与在杂种中具有更多父本形态特征的加勒比鹿角珊瑚物种相反。这些结果进一步表明，卵中的一些遗传因素可能会影响印度太平洋地区群体形状的确定。目前，我们认为不同种间具有中间形态的菌落是种内形态变异，但它们可能是真实的F1杂种。事实上，一个假定的F1杂种表现出与F1杂种相似的形态学和分子特征，因此它在自然界中被认为是“真实的”F1杂种是合理的。
Background: The coral genus Acropora contains more than 150 species with very high morphological diversity. This high diversity may have been caused by repeated hybridization via mass spawning. However, we have little information whether hybrids are formed in these corals. Identifying morphological differences between hybrids and their parental species would provide an opportunity to find wild hybrids in the field and to understand how colony shapes of Acropora have become highly diversified throughout evolutionary history. In the two morphologically distinctive coral species Acropora florida and A. intermedia in the Indo-Pacific, their gametes show high rates of bi-directional intercrossing in vitro, and thus these two species are ideal species to investigate the morphological traits of the hybrids.Methods: We examined morphological characters of F1 hybrids from A. florida to A. intermedia, which were produced from in vitro crossing experiments. To compare morphological differences, we grew juveniles and mature colonies of reciprocal F1 hybrids (FLOint: A. florida eggs x A. intermedia sperm, and INTflo: A. intermedia eggs x A. florida sperm) and of the parental species (purebreds of A. intermedia and A. florida). We analyzed skeletal morphology such as colony size, branch length, and branching number, and compared them with those of a putative F1 hybrid between A. florida and A. intermedia found in the field. We also confirmed the molecular phylogenetic position of F1 hybrids, parental species, and a putative F1 hybrid using the mitochondrial non-coding region.Results: Our morphological analysis revealed that branching number of the F1 hybrids was intermediate relative to the parental species. Moreover, the FLOint hybrids were morphologically more closely related to the maternal species A. florida, and the INTflo hybrids were to A. intermedia. Molecular data showed that A. florida and A. intermedia were clearly divided into two clades, and that F1 hybrids grouped in the Glade based on their maternal parent. A very similar pattern to the INTflo hybrids was obtained for the putative F1 hybrid in nature.Discussion: Our results revealed that F1 hybrids between two Indo-Pacific species A. florida and A. intermedia had intermediate morphology relative to their parent species but reflected the maternal parent more. Similarity to maternal species in hybrids is opposite to the Caribbean Acropora species that had more paternal morphological characters in hybrids. These results further suggest that some genetic factor in eggs is likely to affect determination of colony shape in the Indo-Pacific. At present, we have considered colonies with intermediate morphs between different species to be intra-specific morphological variation, but they may be real F1 hybrids. Indeed, a putative F1 hybrid represented similar morphological and molecular features to the F1 hybrids, and thus it is plausible to be attributed as a "real" F1 hybrid in nature.