Ecological differentiation, speciation, and rarity: How do they match in Tephroseris longifolia agg. (Asteraceae)?

Abstract

Tephroseris longifolia agg. is a complex group of outcrossing perennials distributed throughout Central Europe. Recent morphological study revealed six morphotypes corresponding to five previously distinguished subspecies, together with Alpine and Pannonian morphotypes of T. longifolia subsp. longifolia. The delimited morphotypes differ in relative DNA content, geographical range, and rarity. We compared ecological niches of the six morphotypes in order to assess the impact of ecological differentiation on the speciation processes within the T. longifolia agg. Further, we examined whether morphotypes with small range are more ecologically specialized than their widespread relatives. The distribution area of the aggregate includes the Alps, Apennines, Carpathians, and the Pannonian Basin. Ecological variables linked to climate, topography, soil, and vegetation were gathered from 135 circular plots recorded in 35 localities. Related variables were grouped to describe the partial ecological niches: climatic, topographic, pedological, biotic, and coenotic (based either on vascular plants or on bryophytes), each of them visualized as an envelope in the two‐dimensional nonmetric multidimensional scaling ordination space. Each partial ecological niche for a given morphotype was characterized by its position (location of the envelope centroid), breadth (surface of the envelope), and overlaps with envelopes of the other morphotypes. Mantel statistics based on Spearman correlation coefficients were used to quantify differentiation of morphotypes in ecological parameters represented by the partial ecological niches. The significant niche differentiation was confirmed for climatic, topographic, pedological, and vascular plant‐based coenotic niches. Ecological niche differentiation corresponded well to morphological and partially also to karyological differentiation. Narrowly distributed morphotypes occupied more specific habitats and had narrower ecological niches than their widespread relatives. Ecological differentiation could be considered an important driver in allopatric speciation within the T. longifolia agg. Our results demonstrate that quantification of ecological divergence is helpful in assessing evolutionary history of closely related taxa.

Genome Size Variation in Dianthus sylvestris Wulfen sensu lato (Caryophyllaceae)

“…Griseb. & Schenk [ 26 ], and Minuartia verna (L.) Hiern [ 8 ], albeit sometimes argued to be of minor evolutionary relevance [ 24 ] or suggested to be a result of an experimental artefact [ 27 ]. Nevertheless, this variation can be a result of microevolutionary differentiation and can reflect taxonomic heterogeneity [ 28 ].…”

“…Multiple studies have shown correlations between intraspecific variation of GS and morphological or environmental factors, as well as geographical distribution [ 5 , 26 , 30 , 31 , 32 , 33 , 34 , 35 ], but exact causes of this variation, and thus the interpretation of GS heterogeneity, remains a challenging task [ 35 , 36 , 37 ]. For instance, GS is a characteristic that may be related to the variation in plant phenology [ 38 ] and water availability [ 36 ], and may affect morphological characteristics such as seed size, nuclear and cell volumes, and duration of mitotic and meiotic cycles [ 39 ].…”

Seed traits of species from South Brazilian grasslands with contrasting distribution

“…Kelissa brasiliensis and H. pulchella also present narrower distributions than octoploid H. lahue. Even knowing that seed production alone cannot explain species endemism, rarity or restricted natural distribution (Münzbergová 2005;Powell et al 2011;Gabrielová et al 2013;Janišová et al 2018), rarer species often produce fewer seeds than their common relatives (Murray et al 2002;Lavergne et al 2004). Moreover, seed mass, which is expected to be inversely proportional to the number of seeds produced (Moles & Westoby 2004), was another almost fulfilled tradeoff premise, except for the octoploid H. lahue (i.e., with a large production of heavy seeds).…”

A cytosystematic study of the Dianthus virgineus complex (Caryophyllaceae) in the Central Mediterranean

“…In the absence of polyploidy, GS can show a certain degree of variation within homoploid plant groups (Šmarda & Bureš, 2006; Loureiro et al, 2010; Frajman et al, 2015; Lazarević et al, 2015; Janišová et al, 2018), thus reflecting evolutionary dynamics not affected by genomic mutations (Pellicer et al, 2018). Neutral processes (Kang et al, 2014) and natural selection (Faizullah et al, 2021; Schley et al, 2022) can shape the amount of noncoding repetitive sequences in a genome, thus influencing GS variation (Macas et al, 2015; Hloušková et al, 2019).…”