The quantitative genetics of floral trait variation in Lobelia:: Potential constraints on adaptive evolution
The quantitative genetics of floral trait variation in Lobelia:: Potential constraints on adaptive evolution
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DOI：
10.1111/j.0014-3820.2004.tb00406.x
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发表时间：
2004-04-01
期刊：
影响因子：
3.3
通讯作者：
Caruso, CM
中科院分区：
文献类型：
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作者：
Caruso, CM
尽管传粉者介导的自然选择已经在许多花性状和许多物种上得到了测量，但在多大程度上限制了选择产生最佳花型表型的研究较少。特别是，花朵大小和花朵数量之间的负相关被认为是花卉展示演变的主要制约因素，但很少有实证研究记录这种权衡。为了确定花展示适应性进化的遗传限制的可能性，我估计了两个种群的花性状变异的数量遗传基础。对温室栽培的半同胞家系进行了限制极大似然(REML)分析，估计了花数和6个花大小的遗传方差和协方差。两个居群的7个花卉性状均存在显著的遗传变异。花数与一个群体中的四个花大小指标和另一个群体中的三个花大小指标呈负相关。当遗传方差-协方差矩阵与表型选择梯度的现场估计相结合时，预测的多变量进化响应与花数的选择梯度和花大小的6个度量中的5个在符号上小于或相反，这表明这些性状的进化受到遗传限制。更广泛地说，我的结果表明，花卉展示的适应性进化可以受制于花大小和花朵数量之间的权衡，正如许多花进化理论模型所假设的那样。
Although pollinator-mediated natural selection has been measured on many floral traits and in many species, the extent to which selection is constrained from producing optimal floral phenotypes is less frequently studied. In particular, negative correlations between flower size and flower number are hypothesized to be a major constraint on the evolution of floral displays, yet few empirical studies have documented such a trade-off. To determine the potential for genetic constraints on the adaptive evolution of floral displays, I estimated the quantitative genetic basis of floral trait variation in two populations of Lobelia siphilitica. Restricted maximum likelihood (REML) analyses of greenhouse-grown half-sib families were used to estimate genetic variances and covariances for flower number and six measures of flower size. There was significant genetic variation for all seven floral traits in both populations. Flower number was negatively genetically correlated with four measures of flower size in one population and three measures in the other. When the genetic variance-covariance matrices were combined with field estimates of phenotypic selection gradients, the predicted multivariate evolutionary response was less than or opposite in sign to the selection gradient for flower number and five of six measures of flower size, suggesting genetic constraints on the evolution of these traits. More generally, my results indicate that the adaptive evolution of floral displays can be constrained by tradeoffs between flower size and number, as has been assumed by many theoretical models of floral evolution.