Dissection of leaf morphological traits from isolated and declined relict populations of Ulmus laevis reveals putative random ecotype evolution

Abstract

Ulmus laevis Pallas is a rare and endangered tree species in the northern part of Belgium, restricted to a minimal amount of natural populations that mainly consist of a strongly reduced number of individuals. Probably isolated for several generations, random phenotypic variation in the strongly declined populations can be hypothesised. We analysed U. laevis trees grown in a field trial with a single-tree-plot design (completely randomised). The plants were vegetatively propagated through cuttings from nearly all known natural relict populations in Flanders. We analysed three short-shoot leaves from different ramets from different genotypes from eleven natural populations. Leaf size and shape variables were computed using landmark and procruste methods. We visualised the variability in leaf morphology in a principal component analysis (PCA) including shape, size, and categorical morphological variables. The variance structure of the morphological variables was studied applying mixed modelling methods. The overall PCA distinguished two deviating natural populations. The Zandhoven population showed a deviating simple leaf margin toothing, correlated with larger numbers of split secondary veins. The Halle population is characterised by absence of pubescence at the lower side of the leaves. Both relict populations with deviating morphological leaf characteristics may point to an ecotype evolution putatively due to isolation combined with greatly diminished population sizes. The variance structure analysis of individual leaf variables showed that the deviating categorical leaf characters are under stronger genetic control (specialist characters) compared to the more plastic variables.

Geometric morphometrics and phylogenetic analysis of Delphinium taxa from south of Russia

“…Методы геометрической морфометрии нашли широкое применение в ботанике. Много исследований посвящено именно выяснению специфики изменчивости форм тех или иных структурных элементов разных видов (Conesa et al, 2012;Mijnsbrugge et al, 2016;Chitwood, Otoni, 2017;Miljković et al, 2019;Neto et al, 2019;Márquez et al, 2021;Strelin et al, 2021). Однако до последнего времени отсутствуют работы по геометрической морфометрии представителей рода Delphinium.…”

Dissecting Taxonomic Variants within Ulmus spp. Complex in Natural Forests with the Aid of Microsatellite and Morphometric Markers

“…They analyzed eight leaf traits on European elm species: leaf length and width, petiole length, base asymmetry, and four tooth characteristics. Several authors [29][30][31][32][33][34] have used these above-mentioned and additional parameters, e.g., Elowsky et al [29] used the leaf tooth parameters to determine U. rubra and U. pumila hybrids; Myking and Yakovlev [30] studied the length-to-width ratio, the presence of lateral lobes, and the method of leaf tapering to assess the leaf variability in U. glabra; Vander Mijnsbrugge et al [31] used leaf morphological traits to detect the diversity of isolated and declined relict populations of U. laevis in a field trial with a single-tree-plot design; and Zebec et al [32][33][34] studied inter-population and intra-population morphological variability of foliar traits in natural populations of U. glabra [32] and U. minor [33,34]. In Lithuania, elm species and hybrids were studied based on 14 leaf morphology traits by Petrokas and Baliuckas [35].…”