遗传和表型种内多样性在生物体的生态和进化动力学中发挥着至关重要的作用。一些研究比较了表型趋异 (Pst) 和中性位点分化 (Fst)，以推断遗传漂变和自然选择在群体分化中的相对作用（Pst - Fst 比较）。我们首次评估并比较了两种关键大型植物芦苇和黄花在叶片性状水平上的遗传变异和分化。为此，我们量化并描述了意大利中北部五个湖泊系统中这两个物种的遗传结构和表型多样性。然后我们研究了遗传漂变和自然选择对叶性状分化（Pst - Fst）的相对作用，假设 Fst 反映仅由遗传漂变引起的分歧，而 Pst 还纳入了选择性动态对表型的影响。就遗传结构而言，P. australis 的结果与其他意大利和欧洲同种种群的观察结果一致。相反，N. utea 在位点水平上表现出比预期更复杂的遗传结构，这可能是由于遗传隔离及其混合交配系统的综合影响。两个物种在位点内部和位点之间的叶功能性状都表现出高度变异性，突出了高度的表型可塑性。Pst - Fst 比较显示 P. australis 中存在定向选择的总体趋势，而 N. utea 中则存在更复杂的模式。事实上，N.表型分化的驱动因素。黄体在大多数位点表现出稳定和定向选择或中性发散的可变组合。营养繁殖相对于有性繁殖的盛行导致澳洲拟南芥种群以少数能够很好适应当地条件的克隆为主，包括对环境做出可塑性反应的表型。相比之下，在黄藻中，混合交配系统和遥远地点之间的地理隔离的相互作用往往会减少远交衰退的影响，并为适应能力提供遗传基础。对这两种关键大型植物遗传结构的首次联合分析使我们能够更好地了解遗传漂变和自然选择在以 P. australis 和 N. utea 为主的栖息地表型性状多样化中的相对作用。
Both genetic and phenotypic intraspecific diversity play a crucial role in the ecological and evolutionary dynamics of organisms. Several studies have compared phenotypic divergence (Pst) and differentiation of neutral loci (Fst) to infer the relative roles of genetic drift and natural selection in population differentiation (Pst - Fst comparison). For the first time, we assessed and compared the genetic variation and differentiation at the leaf trait level in two key macrophytes, Phragmites australis and Nuphar lutea. To this aim, we quantified and described the genetic structure and phenotypic diversity of both species in five lake systems in north-central Italy. We then investigated the relative roles of genetic drift and natural selection on leaf trait differentiation (Pst - Fst), assuming that Fst reflects divergence caused only by genetic drift while Pst also incorporates the effects of selective dynamics on the phenotype. In terms of genetic structure, the results for P. australis were in line with those observed for other Italian and European conspecific populations. Conversely, N. lutea showed a more complex genetic structure than expected at the site level, likely due to the combined effect of genetic isolation and its mixed mating system. Both species exhibited high variability in leaf functional traits within and among sites, highlighting a high degree of phenotypic plasticity. Pst - Fst comparisons showed a general tendency towards directional selection in P. australis and a more complex pattern in N. lutea. Indeed, the drivers of phenotypic differentiation in N. lutea showed a variable mix of stabilizing and directional selection or neutral divergence at most sites. The prevalence of vegetative over generative reproduction leads P. australis populations to be dominated by a few clones that are well adapted to local conditions, including phenotypes that respond plastically to the environment. In contrast, in N. lutea the interaction of a mixed mating system and geographical isolation among distant sites tends to reduce the effect of outbreeding depression and provides the genetic basis for adaptive capacity. The first joint analysis of the genetic structure of these two key macrophytes allowed a better understanding of the relative roles of genetic drift and natural selection in the diversification of phenotypic traits within habitats dominated by P. australis and N. lutea.
