Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
Department of Plant Biology, The University of Vermont, Burlington, VT, 05405, USA.
New Phytol. 2019 Jul;223(2):1009-1022. doi: 10.1111/nph.15844. Epub 2019 May 10.
Genetic correlations among different components of phenotypes, especially those resulting from pleiotropy, can constrain or facilitate trait evolution. These factors could especially influence the evolution of traits that are functionally integrated, such as those comprising the flower. Indeed, pleiotropy is proposed as a main driver of repeated convergent trait transitions, including the evolution of phenotypically similar pollinator syndromes. We assessed the role of pleiotropy in the differentiation of floral and other reproductive traits between two species - Jaltomata sinuosa and J. umbellata (Solanaceae) - that have divergent suites of floral traits consistent with bee and hummingbird pollination, respectively. To do so, we generated a hybrid population and examined the genetic architecture (trait segregation and quantitative trait locus (QTL) distribution) underlying 25 floral and fertility traits. We found that most floral traits had a relatively simple genetic basis (few, predominantly additive, QTLs of moderate to large effect), as well as little evidence of antagonistic pleiotropy (few trait correlations and QTL colocalization, particularly between traits of different classes). However, we did detect a potential case of adaptive pleiotropy among floral size and nectar traits. These mechanisms may have facilitated the rapid floral trait evolution observed within Jaltomata, and may be a common component of rapid phenotypic change more broadly.
表型不同成分之间的遗传相关性，特别是那些由多效性引起的相关性，可以限制或促进性状进化。这些因素可能特别影响功能上整合的性状的进化，例如那些组成花的性状。事实上，多效性被认为是重复趋同性状转变的主要驱动力，包括表型相似的传粉者综合征的进化。我们评估了多效性在两种物种（茄科的 Jaltomata sinuosa 和 J. umbellata）之间花部和其他繁殖性状分化中的作用，这两种物种具有不同的花部性状，分别与蜜蜂和蜂鸟传粉相一致。为此，我们生成了一个杂交群体，并检查了 25 个花部和育性性状的遗传结构（性状分离和数量性状位点（QTL）分布）。我们发现，大多数花部性状具有相对简单的遗传基础（少数主要为加性的、中等到大效应的 QTL），并且很少有拮抗多效性的证据（很少有性状相关性和 QTL 共定位，特别是不同类别的性状之间）。然而，我们确实在花部大小和花蜜性状之间检测到了一个潜在的适应性多效性的例子。这些机制可能促进了 Jaltomata 内部观察到的花部性状的快速进化，并且可能是更广泛的快速表型变化的共同组成部分。
