Dipartimento di Scienze della Terra dell'Ambiente e della Vita (DISTAV), University of Genoa, Corso Europa 26, 16132, Genoa, Italy.
Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, Avignon Université, CNRS, IRD, Technopôle de l'Arbois-Méditerranée, BP 80, 13545, Aix-en-Provence Cedex 4, France.
Oecologia. 2021 Jan;195(1):93-103. doi: 10.1007/s00442-020-04806-6. Epub 2020 Dec 2.
Geographical limits of species' distributions are assumed to be coincident with ecological margins, although this assumption might not always be true. Indeed, harsh environments such as Alpine and Mediterranean ecosystems may favour high phenotypic variability among populations, especially those in peripheral sites. Floral traits are often found to be less variable and less affected by environmental heterogeneity than vegetative traits because variation in the former may have negative effects on fitness. For this reason, it is important to quantify variation in floral traits and plant fecundity in study range limits. The objective of the study is to examine phenotypic variation and differences in reproduction in endemic Lilium pomponium in the Maritime and Ligurian Alps in relation to environmental variation across its distribution range. In this species, marginal climatic populations occur both in the peripheral and central geographical locations of the distribution range; hence, geographical and ecological gradients are not concordant. Floral trait variation is related to local environmental conditions with an array of interactions among resource availability, potential pollen limitation and population size that are differentially related to floral traits. Contrary to the general expectation, all central and peripheral populations had similar, moderate seed production with each group limited by different factors acting on different stages of the life-history strategy. Our results are in line with the idea that general expectations are confirmed only when its assumptions are met and that the differences in pollination environment along an environmental gradient may not be the main determinant of the distribution limit.
物种分布的地理界限被认为与生态边缘重合，尽管这种假设并不总是正确的。事实上，阿尔卑斯山和地中海等恶劣环境可能有利于种群之间表现型的高度变异，尤其是在边缘地区。与营养体特征相比，花部特征通常表现出较少的变异性和较少受到环境异质性的影响，因为前者的变异可能对适应性产生负面影响。出于这个原因，在研究范围的限制内量化花部特征和植物繁殖力的变异性是很重要的。本研究的目的是检验在整个分布范围内，与环境变化相关的特有百合属植物 P. pomponium 在边缘气候种群中的表型变异和繁殖差异。在这个物种中，边缘气候种群既存在于分布范围的边缘地理区域，也存在于中心地理区域；因此，地理和生态梯度并不一致。花部特征的变异与局部环境条件有关，资源可用性、潜在花粉限制和种群大小之间存在一系列相互作用，这些相互作用与花部特征不同程度地相关。与普遍预期相反，所有中心和边缘种群都具有相似的、中等的种子产量，每个群体都受到不同因素的限制，这些因素作用于生活史策略的不同阶段。我们的结果与以下观点一致，即只有在满足其假设的情况下，普遍预期才会得到证实，而沿环境梯度的授粉环境差异可能不是分布限制的主要决定因素。
