The Genetic and Developmental Basis of an Exaggerated Craniofacial Trait in East African Cichlids
The Genetic and Developmental Basis of an Exaggerated Craniofacial Trait in East African Cichlids
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DOI：
10.1002/jez.b.22641
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发表时间：
2015-12-15
影响因子：
2.2
通讯作者：
Albertson, R. Craig
中科院分区：
文献类型：
--
作者：
Concannon, Moira R.;Albertson, R. Craig
一种夸张特征的进化可能导致一种新的形态，使有机体能够利用新的生态位。这些表型的分子基础可以揭示独特特征的进化。在这里，我们研究了现代单色素丽鱼的一种罕见的形态创新，这是一种纤维组织瓣，导致鼻部明显突出，这仅限于马拉维湖丽鱼的一个属(拉贝托利乌斯属)。我们比较了我们的焦点物种L.fuelleborni(LF)的襟翼大小与其他密切相关的慈鱼物种的同源地标，这些标志物显示出与LF有一系列生态重叠，并证明在马拉维慈济鱼物种之间襟翼大小的差异是不连续的。我们进一步证明，LF的襟翼发育始于早期幼体阶段，并随着身体大小的变化而异速扩展。然后，我们使用一个F-2杂交作图群体，该群体是通过将LF与缺乏这一性状的紧密生态竞争对手--金鱼草“红颊”(TRC)杂交而获得的，以确定影响瓣膜发育的数量性状基因座(QTL)。总而言之，我们确定了四个与瓣片大小变化相关的基因座，对于每个座位，LF等位基因导致了更大的瓣片。接下来，我们用群体基因组数据交叉参考我们的QTL图谱，比较Lf和TRC的自然群体，以确定每个QTL区间内的不同多态。文中还讨论了与襟翼发育相关的候选基因。总而言之，这些数据表明了这种形态创新的相对简单和易处理的遗传基础，这与其明显的突然和跳跃的进化史是一致的。(C)2015年威利期刊公司。
The evolution of an exaggerated trait can lead to a novel morphology that allows organisms to exploit new niches. The molecular bases of such phenotypes can reveal insights into the evolution of unique traits. Here, we investigate a rare morphological innovation in modern haplochromine cichlids, a flap of fibrous tissue that causes a pronounced projection of the snout, which is limited to a single genus (Labeotropheus) of Lake Malawi cichlids. We compare flap size in our focal species L. fuelleborni (LF) to homologous landmarks in other closely related cichlid species that show a range of ecological overlap with LF, and demonstrate that variation in flap size is discontinuous among Malawi cichlid species. We demonstrate further that flap development in LF begins at early juvenile stages, and scales allometrically with body size. We then used an F-2 hybrid mapping population, derived via crossing LF to a close ecological competitor that lacks this trait, Tropheops "red cheek" (TRC), to identify quantitative trait loci (QTL) that underlie flap development. In all, we identified four loci associated with variation in flap size, and for each the LF allele contributed to a larger flap. We next cross-referenced our QTL map with population genomic data, comparing natural populations of LF and TRC, to identify divergent polymorphisms within each QTL interval. Candidate genes for flap development are discussed. Together, these data indicate a relatively simple and tractable genetic basis for this morphological innovation, which is consistent with its apparently sudden and saltatory evolutionary history. (C) 2015 Wiley Periodicals, Inc.