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Geographic range of Salix myrsinifolia in Europe according to Chmelař and Meusel (1986) supplemented with local data from Zieliński (1976) and Sugier et al. (2011). a Distribution and frequency of plastid DNA haplotypes (unique haplotypes showed with red font, T trioecious pop., D dioecious pop.); b Bayesian consensus tree derived from 10 cpDNA sequences from trnL, trnT-trnL and accD-psaI intergenic spacers (bootstrap support >50% are given by the corresponding branches) (c) and statistical parsimony network (d)
Source publication
Gene flow in plant populations is heavily affected by species sexual systems. In order to study the effect of sexual systems on genetic structure, we examined plastid and nuclear DNA of 12 dioecious (males and females) and 18 trioecious (males, females and hermaphrodites) populations of Salix myrsinifolia—a boreal shrub with slow range expansion. P...
Citations
... Polyploids have been observed to be associated with loss of dioecy of diploid progenitors, with changes occurring to monoecy, e.g., in hexaploid Diospyros kaki (Akagi et al., 2016), to hermaphroditism, e.g., in tetraploid Empetrum (Anderberg, 1994), or to monoecy and androdioecy in tetra-to dodecaploid Mercurialis (Pannell et al., 2004;Gerchen et al., 2022). In willows (Salix), shifts to diverse sexual systems occur in polyploids (Mirski, 2014;Mirski et al., 2017). These transitions to non-dioecious systems might be favored by selection for reproductive assurance by uniparental reproduction, especially in colonization scenarios (Ashman et al., 2013). ...
Dioecy is rare in flowering plants (5–6% of species), but is often controlled genetically by sex-linked regions (SLRs). It has so far been unclear whether, polyploidy affects sex chromosome evolution, as it does in animals, though polyploidy is quite common in angiosperms, including in dioecious species. Plants could be different, as, unlike many animal systems, degenerated sex chromosomes, are uncommon in plants. Here we consider sex determination in plants and plant-specific factors, and propose that constraints created at the origin of polyploids limit successful polyploidization of species with SLRs. We consider the most likely case of a polyploid of a dioecious diploid with an established SLR, and discuss the outcome in autopolyploids and allopolyploids. The most stable system possibly has an SLR on just one chromosome, with a strongly dominant genetic factor in the heterogametic sex (e.g., xxxY male in a tetraploid). If recombination occurs with its homolog, this will prevent Y chromosome degeneration. Polyploidy may also allow for reversibility of multiplied Z or X chromosomes into autosomes. Otherwise, low dosage of Y-linked SLRs compared to their multiple homologous x copies may cause loss of reliable sex-determination at higher ploidy levels. We discuss some questions that can be studied using genome sequencing, chromosome level-assemblies, gene expression studies and analysis of loci under selection.
... Studies of genetic diversity, divergence and gene flow among populations have been conducted on several Salix species (e.g., S. hukaoana, S. viminalis, S. daphnoides, S. caprea, S. psammophila, S. myrsinifolia, S. alba) using various genetic markers (Kikuchi et al. 2011;Trybush et al. 2012;Sochor et al. 2013;Berlin et al. 2014;Perdereau et al. 2014;Mirski et al. 2017;Değirmenci et al. 2019;Hao et al. 2019). However, to date, there has been no comprehensive study of population-level genetic variation in S. alba sampled from diverse riparian ecosystems. ...
Background
Salix alba is a pioneer species of river ecosystems throughout Turkey. Its genetic diversity and population structure across these ecosystems is currently unknown.
Aims
We investigated genetic diversity in Turkish S. alba to assess factors likely to shape the genetic structure of the species and to assist with conservation recommendations.
Methods
Six hundred and forty-six individuals from 10 major river systems in Turkey were genotyped using 15 microsatellite markers. Between one and five sub-populations were sampled from each river system with 23 sub-populations sampled in total.
Results
Populations contained moderately high levels of genetic diversity. Five genetic groups were detected by Bayesian clustering, with samples from particular river systems mainly assigned to particular genetic groups. This revealed a geographic structure, also detected by principal coordinate analysis, showing that particular river system populations in different parts of Turkey were genetically similar to each other but different from those in other parts of the country.
Conclusion
Genetic isolation caused by geographic distance (in part) and natural barriers among river systems appear to have shaped the genetic structure of populations. The results have important implications for the conservation of genetic resources within S. alba and restoration of degraded Turkish populations of the species.
... During the Last Glacial Maximum (LGM), all natural vegetation of temperate Europe changed substantially. This also applies to the development history of various Salix species, for which results have been obtained from numerous paleobotanical studies and from research using modern genetic methods (Palmé et al. 2003;Reichs et al. 2007;Stamati et al. 2007;Alsos et al. 2009;Sochor et al. 2013;Berlin et al. 2014;Mirski et al. 2017;Wagner et al. 2018;Gouker et al. 2019;Hao et al. 2019;Liu et al. 2020;Wagner et al. 2020). In general, S. lapponum L. [Sp. ...
Salixlapponum is a cold-tolerant relict species in Europe that occurs in several sites, probably reflecting previous migration routes of S.lapponum during the Pleistocene. However, only a few data are available on the genetic structures of populations of S.lapponum. In this study, we use PCR-ISSR markers to investigate genetic variation in 19 European populations of S.lapponum L. AMOVA analysis shows that most of the variation (55.8%) occurs within populations; variability among groups accounts for 19.7%. An AMOVA analysis based on four groups determined by STRUCTURE analysis shows similar results: variability of 54.1% within the population and variability of 18.9% between the four population groups, based on geographic regions. Within individual geographic groups, which are characterised by the studied populations, the lowest variability (as well as the highest homogeneity) was found in populations located in Belarus. The obtained results are consistent with our expectations that the European Lowland could be a significant geographic barrier for gene flow over large geographic distances for S.lapponum. Both the Scandinavian and Belarusian populations, as well as those coming from NE Poland, are characterised by significant genetic distinctiveness. However, some populations from NE Poland and the Sudetes show similarities with populations from other geographic regions, indicating existing genetic relationships between them. Moreover, the results suggest a fairly clear division of the population into 4 emerging geographic regions, although separated by a geographical barrier: the Polish lowland, which forms part of the larger geographic unit known as the European Lowland.
... 1A). These theoretical predictions are now at odds with accumulating empirical evi- dence for trioecy in crustaceans (Sassaman and Weeks 1993), plants (Mirski et al. 2017), and nematodes (Chaudhuri et al. 2015;Kanzaki et al. 2017). Auanema is a recently described nematode genus with two trioecious species, A. rhodensis and A. freiburgensis (Kanzaki et al. 2017) and is distantly related to the trioecious Heterorhabditis sp. ...
Sex is determined by chromosomes in mammals but it can be influenced by the environment in many worms, crustaceans and vertebrates. Despite this, there is little understanding of the relationship between ecology and the evolution of sexual systems. The nematode Auanema freiburgensis has a unique sex determination system in which individuals carrying one X chromosome develop into males while XX individuals develop into females in stress‐free environments and self‐fertile hermaphrodites in stressful environments. Theory predicts that trioecious populations with coexisting males, females and hermaphrodites should be unstable intermediates in evolutionary transitions between mating systems. In this article we study a mathematical model of reproductive evolution based on the unique life history and sex determination of A. freiburgensis. We develop the model in two scenarios, one where the relative production of hermaphrodites and females is entirely dependent on the environment and one based on empirical measurements of a population that displays incomplete, ‘leaky’ environmental dependence. In the first scenario environmental conditions can push the population along an evolutionary continuum and result in the stable maintenance of multiple reproductive systems. The second ‘leaky’ scenario results in the maintenance of three sexes for all environmental conditions. Theoretical investigations of reproductive system transitions have focused on the evolutionary costs and benefits of sex. Here, we show that the flexible sex determination system of A. freiburgensis may contribute to population‐level resilience in the microscopic nematode's patchy, ephemeral natural habitat. Our results demonstrate that life history, ecology and environment may play defining roles in the evolution of sexual systems. This article is protected by copyright. All rights reserved
... 1a). These theoretical 40 predictions are now at odds with accumulating empirical evidence for trioecy in crustaceans 41 (Sassaman and Weeks, 1993), plants (Mirski et al., 2017), and nematodes (Chaudhuri et al., 2015;42 Kanzaki et al., 2017). Auanema is a recently described nematode genus with two trioecious species, ...
Sex is determined by chromosomes in mammals but it can be influenced by the environment in many worms, crustaceans and vertebrates. Despite this, there is little understanding of the relationship between ecology and the evolution of sexual systems. The nematode Auanema freiburgensis has a unique sex determination system in which individuals carrying one X chromosome develop into males while XX individuals develop into females in stress-free environments and self-fertile hermaphrodites in stressful environments. Theory predicts that trioecious populations with coexisting males, females and hermaphrodites should be unstable intermediates in evolutionary transitions between mating systems. In this article we study a mathematical model of reproductive evolution based on the unique life history and sex determination of A. freiburgensis. We develop the model in two scenarios, one where the relative production of hermaphrodites and females is entirely dependent on the environment and one based on empirical measurements of a population that displays incomplete, 'leaky' environmental dependence. In the first scenario environmental conditions can push the population along an evolutionary continuum and result in the stable maintenance of multiple reproductive systems. The second 'leaky' scenario results in the maintenance of three sexes for all environmental conditions. Theoretical investigations of reproductive system transitions have focused on the evolutionary costs and benefits of sex. Here, we show that the flexible sex determination system of A. freiburgensis may contribute to population-level resilience in the microscopic nematode's patchy, ephemeral natural habitat. Our results demonstrate that life history, ecology and environment may play defining roles in the evolution of sexual systems.
... contains supplementary material, which is available to authorized users. population structure Huang et al. 2015;Mirski et al. 2017), genetic linkage maps (Berlin et al. 2010;Zhang et al. 2016), quantitative trait loci (Ghelardini et al. 2014;Hallingbäck et al. 2016), and functional genes (Bi et al. 2016;Rao et al. 2016;Zhang et al. 2017). In the Salicaceae family, Populus trichocarpa and P. euphratica were the first to undergo whole genome sequencing (Tuskan et al. 2006;Ma et al. 2013), recently followed by Salix purpurea (Salix purpurea v1.0, DOE-JGI, http://phytozome. ...
As the largest genus in the family Salicaceae, Salix L. has great potential in industrial, ornamental, and bioenergy-related applications. Despite their comprehensive importance, the genetic and genomic resources available for various willow species are still insufficient. In the present study, the transcriptomes of S. babylonica and S. suchowensis were sequenced using Roche 454 pyrosequencing and screened for expressed sequence tagged simple sequence repeat (EST-SSR) markers. A total of 280,074 and 267,030 reads with an average length of 432 bp and 398 bp were obtained for S. babylonica and S. suchowensis, respectively. The de novo assemblies yielded 40,271 unigenes for S. babylonica and 55,083 unigenes for S. suchowensis, of which 32,506 and 42,482 unigenes were respectively annotated in at least one of the four reference databases. A total of 1479 differentially expressed genes were identified between the two species. A set of 1083 SSR markers (424 for S. babylonica and 659 for S. suchowensis) were developed from the expressed sequence assemblies. Of the 300 randomly selected EST-SSR markers, 295 (98.3%) were polymorphic among different individuals of S. babylonica and of S. eriocephala. High rates of cross-species/genus amplification were also observed within 16 different species. In conclusion, this transcriptomic analysis provides novel resources for functional genomic research and can be used to improve the efficiency of genetics and breeding applications for these Salix species.
... Within the genus Salix, genetic diversity, divergence and gene flow among populations, as well as linkage disequilibrium were also investigated in several species, including S. viminalis L., S. schwerinii E. Wolf, S. herbacea L. and S. myrsinifolia Salisb. (Alsos, et al. 2009, Berlin, et al. 2011, Mirski, et al. 2017). However, owing to the different environments and willow species, within-stand features and between-stand distances, and willow species, this information is not comparable with that emerging from our case study. ...
Remnant riparian woodlands have an important landscape function, due to their ability to act as ecological corridors. In this study we used molecular markers to assess the genetic variation occurring within and between spontaneous white willow (Salix alba L.) riparian woodlands. Our main goal was to evaluate the extent to which the fragmentation of a woodland corridor along a heavily impacted river in northeastern Italy and stand structural conditions may have affected the population genetics. Although having different structures, the three examined white willow stands showed high estimates of genetic similarity, as well as low genetic differentiation between them, indicating that they shared a similar gene pool and that the stands could result from a common set of individual genotypes, and should be regarded as metapopulations. The magnitude of genetic diversity within each of the stands and genetic differentiation between them, despite their high sexual reproductive capacity associated with a highly marked gene flow, suggest that these stands are dynamic and capable of adaptive responses to possible changes in their fluvial environment. However, the factors influencing genetic diversity should be interpreted from a long-term perspective. Fluvial geomorphic patterns in regulated rivers may be modified to a degree that could lead to changes in dispersal processes, sexual reproduction vs. asexual propagation, and hence genetic diversity.
Background
Swertia perennis (Gentianaceae) is a perennial diploid and clonal plant species that is discontinuously distributed in peat bogs in the mountains of Europe, Asia and North America as well as in the lowlands of Europe. The current geographical dispersion of S. perennis is probably the result of quaternary climatic changes that have played an important role in determining the distribution of Swertia and other plant and animal species.
Methods
In this study we used molecular techniques and combined data from chloroplast DNA markers ( trn LF region and trn H- psb A spacer) to elucidate the phylogeography of S. perennis in Europe. Plants were collected from 28 populations in different locations in the lowlands and mountainous areas of Europe (e.g., the Carpathians, Sudetes, Bohemian Forest and Alps). cDNA was analysed to detect the genetic relationship between specimens from different locations.
Results
A total of 20 haplotype s were identified across the dataset. They were characterised by a high level of genetic variability but showed a lack of phylogeographical structure. This pattern may be the result of repeated recolonization and expansion from several areas. Such genetic differentiation may also be attributed to the relatively long-term isolation of S. perennis in Pleistocene refugia in Europe, which resulted in independent separation of different cpDNA phylogenetic lineages and variation in the nucleotide composition of cpDNA.
Discussion
The lack of strong phylogeographical structure makes it impossible to indicate the centre of haplotype diversity; however, refugia located in the Carpathians, Sudetes or Alps are the most probable sites where S. perennis existed in Europe. This lack of structure may also indicate a high level of gene flow in times when the landscape and fen systems were not fragmented in numerous geographically-isolated populations. This makes it difficult to speculate about the relationships between Asiatic and European plant populations and the origin and distribution of this species in Europe. Today, it seems to be restricted due to the occurrence of plants which clearly reflects the genetic variability from the ancient period.
