Contrasting effects of local environment and grazing pressure on the genetic diversity and structure of Artemisia frigida

Abstract

Drylands count among the most globally extensive biomes, and while many desert and dry rangeland ecosystems are under threat, genetic structures of dryland species are still rarely studied. Artemisia frigida is one of the most widely distributed plant species in the temperate rangelands of Eurasia and North America, and it also dominates in many habitats of Mongolia due to its tolerance to low temperatures, drought and disturbance. Local environmental conditions and grazing pressure can influence species performance and affect spatial patterns of genetic diversity in contrasting ways, and our study set out to evaluate such effects on the genetic diversity and structure of A. frigida. We first developed new species-specific Simple Sequence Repeats (SSRs) markers using whole genome sequencing. We then analysed 11 populations of A. frigida that had been sampled along a large climatic gradient in Mongolia, which were sub-structured according to three levels of grazing intensity. Estimates of genetic diversity at the population level were high (HO = 0.56, HE = 0.73) and tended to increase with higher precipitation and soil nutrient availability. Grazing had no effect on genetic diversity, however, a high number of grazing-specific indicator alleles was found at grazed sites. Genetic differentiation among populations was extremely low (global GST = 0.034). Analysis of Molecular Variance revealed 5% variance between populations along the climatic gradient, with 3% of the variance being partitioned among different grazing intensity levels. We found no relationship between geographic and genetic distances, and thus no isolation by distance in this widely distributed species. The relatively low genetic structuring suggests that considerable gene flow exists among A. frigida populations across the rangelands of Mongolia, in spite of the pervasive grazing in the region.

Phylogeography of Artemisia frigida (Anthemideae, Asteraceae) based on genotyping‐by‐sequencing and plastid DNA data: Migration through Beringia

“…The minimal number of samples per locus was set to 100, the clustering threshold was set to 0.85. Despite indications for tetraploidy (Oyundelger et al, 2021), the ploidy level was taken as unproven, and the maximum number of alleles per site parameter was consequently set to two (biallelic SNPs). As a result, 3,575 sites were omitted, accounting for 8% of the total sites detected.…”

“…This perennial subshrub is an important component of the dry steppe flora, as it is resistant to cold temperatures, drought and mechanical disturbance, especially grazing. Therefore, comprehensive studies on its systematics (Garcia et al, 2011;Pellicer et al, 2011;Riggins & Seigler, 2012) and population genetics within its distribution range have already been conducted (Liu et al, 2012;Oyundelger et al, 2021;Wan et al, 2008;Wang et al, 2004). A number of studies have focused on the cytogenetic diversity of A. frigida (Garcia et al, 2004;Korobkov & Kotseruba, 2015;Korobkov et al, 2014;Pellicer et al, 2007Pellicer et al, , 2010, which revealed diploid and tetraploid individuals with 2n = 2x = 18 and 2n = 4x = 36, respectively.…”

Relationship between genetic and phenotypic variations in natural populations of perennial and biennial sagebrush

“…Two randomly selected individuals of each species from two distinct populations were used to develop new SSR markers by applying whole genome sequencing (WGS). A previous study by Oyundelger et al (2021), gives detailed steps for DNA extraction, library preparation, quality control and bioinformatics in SSR development. Raw sequencing data were submitted to the NCBI Sequence Read Archive (SRA) and made publicly accessible under BioProject: PRJNA680535.…”

“…The continuous plain steppe of Mongolia allows for sufficient genetic exchanges between plant populations, as shown by former studies on the perennial grass Stipa glareosa P.A.Smirn. (Oyundelger et al 2020) and on Artemisia frigida (Oyundelger et al 2021(Oyundelger et al , 2023. In these studies, we detected moderate genetic structuring, which was mostly attributed to the differences in climate and edaphic conditions of the local populations rather than the geographical distance.…”

Genetic Diversity and Population Structure of Rhododendron longipedicellatum, an Endangered Species

“…The evolutionary potential of a species and its ability to withstand adverse environments depend on both the genetic diversity of the species and its population genetic structure (Stebbins, 1950). Different levels of genetic variation and genetic structure of populations can be attributed to multiple factors, such as breeding systems, biological characteristics, evolutionary history, and natural selection (Hamrick & Godt, 1996;Oyundelger et al, 2021;Zhou et al, 2020). The results of this EST-SSR study showed that R. longipedicellatum has high genetic diversity at the species level (He = 0.559, N A = 9.529), and the mean genetic diversity of the five populations investigated (He = 0.507, N A = 5.910) was higher than that of Rhododendron oldhamii (He = 0.284, ranged 0.240-0.336) (Hsieh et al, 2013) and the Rhododendron pseudochrysanthum complex (average He = 0.424) (Chen et al, 2014), but lower than the genetic diversity of Rhododendron jinggangshanicum (He = 0.642) (M. Li et al, 2015) and Rhododendron decorum (He = 0.758) (Wang et al, 2013) based on gSSR markers.…”