Asymmetric contributions of seed and pollen to gene dispersal in the marsh orchid Dactylorhiza umbrosa in Asia Minor

Geographic isolation and long-distance gene flow influence the genetic structure of the blue fan palm Brahea armata (Arecaceae)

The formation of the Baja California Peninsula (BCP) has impacted the microevolutionary dynamics of different species in ways that depend on biological traits such as dispersal capacity. Plants with relatively low levels of vagility have exhibited high genetic divergence between the BCP and Continental mainland. Brahea armata (Arecaceae) is a palm species inhabiting the northern part of the BCP and Sonora; its distribution occurs in isolated oases of vegetation. We aimed to evaluate the influence of the formation of the BCP on the genetic structure of B. armata using nuclear microsatellites and chloroplast markers (cpDNA) to compare patterns of genetic diversity and structure with previous published studies. Because gene flow through seeds is usually more limited compared to pollen flow, we expect to find stronger genetic structure at (cpDNA) than at nuclear markers. Moreover, larger genetic structure might also be explained by the smaller effective population size of cpDNA. We analyzed six microsatellite markers and two cpDNA regions. The main results indicated high levels of genetic differentiation among isolated populations located in the BCP, while low genetic differentiation was found between southern populations of the BCP and Sonora, suggesting long distance gene flow. In contrast, chloroplast markers indicated high levels of genetic structure between BCP and Sonora populations, suggesting asymmetrical gene flow between pollen (measured by nuclear microsatellites) and seed (cpDNA markers). This study provides valuable information on genetic diversity of B. armata that can be relevant for conservation and management; and develops microsatellites markers that can be transferred to other Brahea species.

Population Structure and Genetic Diversity in the Natural Distribution of Neolamarckia cadamba in China

Neolamarckia cadamba (Roxb.) Bosser is a fast-growing deciduous tree species and belongs to the Neolamarckia genus of the Rubiaceae family. This species has great economic and medical values in addition to being an important timber species for multiple industrial purposes. However, few studies have examined the genetic diversity and population structure in the natural distribution of this species in China. Here, we applied both the haploid nrDNA ITS (619 bp for aligned sequences) and mtDNA (2 polymorphic loci) markers to investigate 10 natural populations (239 individuals in total) that covered most of the distribution of the species in China. The results showed that the nucleotide diversity was π = 0.1185 ± 0.0242 for the nrDNA ITS markers and π = 0.00038 ± 0.00052 for the mtDNA markers. The haplotype diversity for the mtDNA markers was h = 0.1952 ± 0.2532. The population genetic differentiation was small (Fstn = 0.0294) for the nrDNA ITS markers but large (Fstm = 0.6765) for the mtDNA markers. There were no significant effects of isolation by distance (IBD), by elevation, and by two climatic factors (annual average precipitation and tem perature). A geographic structure among populations (Nst<Gst) was absent. Phylogenetic analysis showed a highly genetic mixture among individuals of the ten populations. Pollen flow was substantially greater than seed flow (mp/ms ≫ 1.0) and played a dominant role in shaping population genetic structure. The nrDNA ITS sequences were neutral and all local populations did not undergo demographic expansion. The overall results provide fundamental information for the genetic conservation and breeding of this miraculous tree.

New and Noteworthy Taxa of the Genus Dactylorhiza Necker ex Nevski (Orchidaceae Juss.) in Kazakhstan Flora and Its Response to Global Warming

A critical study of the herbarium material representing the orchid genus Dactylorhiza Necker ex Nevski in Kazakhstan was conducted in 2019–2020. The information on the species composition was clarified. Dactylorhiza fuchsii subsp. hebridensis (Wilmott) Soó and D. × kerneri (Soó) Soó were identified for the first time in the country. New taxa were noted for individual botanical and geographical areas. All taxa were presented in the list and annotated with studied herbarium materials from the Kazakhstan area. Based on the collected and available locations for the studied taxa, distribution modeling was carried out for the four taxa (D. incarnata, D. majalis subsp. baltica, D. salina, and D. umbrosa). Bioclimatic data for the present and future (2041–2060) based on four possible scenarios were used. The occurrence of Dactylorhiza representatives in Kazakhstan is threatened by global climate warming. It is likely that some of them may not occur in the country in the future (D. incarnata and D. majalis subsp. baltica), losing up to 99.87% of their modern range or their range may be significantly reduced (D. salina and D. umbrosa), losing up to 80.83% of their present distribution. It is worth considering global changes in planning conservation activities and identifying areas that may play a significant role in the functioning of the national flora in the future.

Effective population size in a partially clonal plant is not predicted by the number of genetic individuals

Estimating effective population size (N _e) is important for theoretical and practical applications in evolutionary biology and conservation. Nevertheless, estimates of N _e in organisms with complex life-history traits remain scarce because of the challenges associated with estimation methods. Partially clonal plants capable of both vegetative (clonal) growth and sexual reproduction are a common group of organisms for which the discrepancy between the apparent number of individuals (ramets) and the number of genetic individuals (genets) can be striking, and it is unclear how this discrepancy relates to N _e. In this study, we analysed two populations of the orchid Cypripedium calceolus to understand how the rate of clonal versus sexual reproduction affected N _e. We genotyped >1000 ramets at microsatellite and SNP loci, and estimated contemporary N _e with the linkage disequilibrium method, starting from the theoretical expectation that variance in reproductive success among individuals caused by clonal reproduction and by constraints on sexual reproduction would lower N _e. We considered factors potentially affecting our estimates, including different marker types and sampling strategies, and the influence of pseudoreplication in genomic data sets on N _e confidence intervals. The magnitude of N _e/N _ramets and N _e/N _genets ratios we provide may be used as reference points for other species with similar life-history traits. Our findings demonstrate that N _e in partially clonal plants cannot be predicted based on the number of genets generated by sexual reproduction, because demographic changes over time can strongly influence N _e. This is especially relevant in species of conservation concern in which population declines may not be detected by only ascertaining the number of genets.