1. Spatio-temporal evolution of shrub willows (Salix subgenus Vetrix clade) on a global scalePia Marinček, Jing Vir Leong, Loïc Pittet, Étienne Léveillé-Bourret, Tommi Nyman, 2026, izvirni znanstveni članek Povzetek: The spatio-temporal evolution of woody plant lineages in the Holarctic is still understudied, limiting our understanding of evolutionary processes that promote higher diversity at higher latitudes in some lineages, which contradicts the latitudinal gradient hypothesis which predicts higher species richness in the tropics. Shrub willows (Salix subgenus Vetrix) comprise about 350 species of which many are adapted to arctic-alpine ecosystems and thus form an important element across the Holarctic region. In this study, we utilized RAD sequencing to estimate the spatio-temporal evolution of the Vetrix clade based on about 140 species covering most of its morphological and geographical diversity. The resolved phylogeny revealed four lineages: the Pan-Himalayan clade, the North American clade and two clades containing species from Eurasia. Widespread circumpolar species form a hybridogenetic grade between the Eurasian and North American clades. Our results confirm that shrub willows originated in the Tertiary, probably in Asia, and that diversification coincided with the climatic cooling in the Pleistocene. At least two radiations were observed, in the Pan Himalayas and in North America. Speciation was further shaped by migration and dispersal in Eurasia, likely accelerated by the uplift of mountain chains, the closure of the Turgai Strait and expansion of suitable habitats. The dated phylogeny revealed that speciation of arctic lineages predates adaptation to high latitudes, as also evident from the fossil record. Small wind-dispersed seeds enabled shrub willows to colonize the expanding arctic tundra regions in the Miocene and their recolonization after the LGM. Given the high observed number of polyploid species equally distributed in all clades and indications of genetic admixture, we assume that species diversity in shrub willows was additionally increased by hybridization and polyploidization.
Ključne besede: biogeography, BAMM, BioGeoBEARS, Holarctic, Northern Hemisphere, RAD sequencing
Objavljeno v DiRROS: 19.03.2026; Ogledov: 560; Prenosov: 508
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2. Evolution of a hybrid zone of willows (Salix L.) in the Alps analysed by RAD-seq and morphometricsPia Marinček, 2022, magistrsko delo Povzetek: Natural hybridization of plants can result in many outcomes with several evolutionary consequences, such as hybrid speciation and introgression. Natural hybrid zones can arise as a result of fluctuating climate during the exchange of glacial and interglacial periods, where species retract and expand their territories, resulting in secondary contacts. On mountain ranges, such as the European Alps, hybrid zones of alpine species are frequently formed where different lineages meet. Willows are a large genus of woody plants with an immense capability of interspecific crossing. About 33 species of this genus inhabit the Alps, where intermediate phenotypes were frequently observed and proclaimed as hybrids, but rarely examined in detail. One of the reasons was a lack of informative molecular markers and suitable analytical tools to analyse this highly diverse and convergent genus. With the development of the RAD-seq technology, several questions regarding willow phylogeny and hybridization could be answered. In this study, a putative hybrid zone of two sister species, S. foetida and S. waldsteiniana, was investigated to study the genomic structure of populations within and outside their contact zone, to find evidence for hybrid speciation or introgression, and to analyse if morphological phenotypes are reflected by their genotypes. Individuals of the two species were sampled across their distribution range in the Alps and examined with the use of RADseq data and morphometric analyses. The results showed that a hybrid zone between the two species was established within the range of their contact zone. Patterns of genetic admixture in homoploid hybrids indicated introgression with asymmetric backcrossing to one of the parental species. Morphometric characteristics of hybrids supported the molecular data and showed intermediacy with a bias towards S. waldsteiniana. Only one potentially divergent hybrid lineage was observed, hinting to a possibility of localised hybrid speciation events.
Ključne besede: alpine plants, hybridization, morphometry, RAD sequencing, master thesis
Objavljeno v DiRROS: 17.01.2025; Ogledov: 1273; Prenosov: 483
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3. Using genomic information for management planning of an endangered perennial, Viola uliginosaKyung Min Lee, Pertti Ranta, Jarmo Saarikivi, Lado Kutnar, Branko Vreš, Maxim Dzhus, Marko Mutanen, Laura Kvist, 2020, izvirni znanstveni članek Povzetek: Species occupying habitats subjected to frequent natural and/or anthropogenic changes are a challenge for conservation management. We studied one such species, Viola uliginosa, an endangered perennial wetland species typically inhabiting sporadi-cally flooded meadows alongside rivers/lakes. In order to estimate genomic diversity, population structure, and history, we sampled five sites in Finland, three in Estonia, and one each in Slovenia, Belarus, and Poland using genomic SNP data with double-digest restriction site-associated DNA sequencing (ddRAD-seq). We found mono-phyletic populations, high levels of inbreeding (mean population FSNP = 0.407-0.945), low effective population sizes (Ne = 0.8-50.9), indications of past demographic ex-pansion, and rare long-distance dispersal. Our results are important in implementing conservation strategies for V. uliginosa, which should include founding of seed banks, ex situ cultivations, and reintroductions with individuals of proper origin, combined with continuous population monitoring and habitat management.
Ključne besede: nature conservation, demography, genomic diversity, population genomics, RAD sequencing, Viola
Objavljeno v DiRROS: 20.01.2022; Ogledov: 2408; Prenosov: 1916
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