Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA.
Departments of Botany and Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
Am J Bot. 2021 May;108(5):844-856. doi: 10.1002/ajb2.1660. Epub 2021 May 25.
Across taxa, vegetative and floral traits that vary along a fast-slow life-history axis are often correlated with leaf functional traits arrayed along the leaf economics spectrum, suggesting a constrained set of adaptive trait combinations. Such broad-scale convergence may arise from genetic constraints imposed by pleiotropy (or tight linkage) within species, or from natural selection alone. Understanding the genetic basis of trait syndromes and their components is key to distinguishing these alternatives and predicting evolution in novel environments.
We used a line-cross approach and quantitative trait locus (QTL) mapping to characterize the genetic basis of twenty leaf functional/physiological, life history, and floral traits in hybrids between annualized and perennial populations of scarlet monkeyflower (Mimulus cardinalis).
We mapped both single and multi-trait QTLs for life history, leaf function and reproductive traits, but found no evidence of genetic co-ordination across categories. A major QTL for three leaf functional traits (thickness, photosynthetic rate, and stomatal resistance) suggests that a simple shift in leaf anatomy may be key to adaptation to seasonally dry habitats.
Our results suggest that the co-ordination of resource-acquisitive leaf physiological traits with a fast life-history and more selfing mating system results from environmental selection rather than functional or genetic constraint. Independent assortment of distinct trait modules, as well as a simple genetic basis to leaf physiological traits associated with drought escape, may facilitate adaptation to changing climates.
在不同的分类群中，沿着快速-缓慢生活史轴变化的营养和生殖特征通常与沿着叶经济谱排列的叶功能特征相关，这表明适应的特征组合受到限制。这种广泛的趋同可能是由种内多效性（或紧密连锁）或自然选择单独施加的遗传限制引起的。了解特征综合征及其组成部分的遗传基础是区分这些替代方案并预测新环境中进化的关键。
我们使用线交叉法和数量性状位点（QTL）作图来描述一年生和多年生猩红金鱼草（Mimulus cardinalis）种群杂交后代的二十个叶功能/生理、生活史和花部特征的遗传基础。
我们为生活史、叶功能和繁殖特征映射了单个性状和多性状 QTL，但没有发现跨类别遗传协调的证据。三个叶功能性状（厚度、光合速率和气孔阻力）的主要 QTL 表明，叶解剖结构的简单变化可能是适应季节性干燥生境的关键。
我们的结果表明，资源获取型叶生理特征与快速生活史和更多自交交配系统的协调是环境选择的结果，而不是功能或遗传限制的结果。不同特征模块的独立组合，以及与干旱逃避相关的叶生理特征的简单遗传基础，可能有助于适应气候变化。
