Population and Landscape Genetics Provide Insights Into Species Conservation of Two Evergreen Oaks in Qinghai–Tibet Plateau and Adjacent Regions

Abstract

The combination of population and landscape genetics can facilitate the understanding of conservation strategy under the changing climate. Here, we focused on the two most diverse and ecologically important evergreen oaks: Quercus aquifolioides and Quercus spinosa in Qinghai–Tibetan Plateau (QTP), which is considered as world’s biodiversity hotspot. We genotyped 1,657 individuals of 106 populations at 15 nuclear microsatellite loci throughout the species distribution range. Spatial patterns of genetic diversity were identified by mapping the allelic richness (AR) and locally common alleles (LCA) according to the circular neighborhood methodology. Migration routes from QTP were detected by historical gene flow estimation. The response pattern of genetic variation to environmental gradient was assessed by the genotype–environment association (GEA) analysis. The overall genetic structure showed a high level of intra-species genetic divergence of a strong west-east pattern. The West-to-East migration route indicated the complex demographic history of two oak species. We found evidence of isolation by the environment in Q. aqu-East and Q. spi-West lineage but not in Q. aqu-West and Q. spi-East lineage. Furthermore, priority for conservation should be given to populations that retain higher spatial genetic diversity or isolated at the edge of the distribution range. Our findings indicate that knowledge of spatial diversity and migration route can provide valuable information for the conservation of existing populations. This study provides an important guide for species conservation for two oak species by the integration of population and landscape genetic methods.

Species Delimitation and Genetic Relationship of Castanopsis hainanensis and Castanopsis wenchangensis (Fagaceae)

“…Nuclear SSR markers have been used to evaluate genetic differentiation among some species of the Fagaceae family, such as between Quercus aquifolioides and Q. spinosa (F CT = 0.26) [17], among Q. aliena, Q. dentata, and Q. variabilis (F CT = 0.21) [18], among Q. acutissima, Q. variabilis, and Q. chenii (F CT = 0.195) [19], and between Castanopsis sieboldii and C. cuspidate (F CT = 0.145) [20]. The genetic differences between different lineages within species have also been evaluated, but they are much lower than the genetic differentiation between species, as revealed by groups within Q. aquifolioides (F CT = 0.04), Q. spinose (F CT = 0.09), C. sieboldii (F CT = 0.014), and C. cuspidata (F CT = 0.095) [17,20]. In this study, we detect high and significant genetic differentiation between C. wenchangensis and C. hainanensis (F CT = 0.243 in AMOVA analysis) based on allelic frequencies of nuclear SSRs, suggesting they are distinct species despite highly morphological similarities.…”

Notes on Sweet orange (Citrus sinensis L. Osbeck) populations’ divergence: Landscape genetics, comparative phylogeny, and Niche modeling

“…In addition to local adaptation, migrating to new favorable locations is also a response pattern of plants to rapid climate changes, which is important for species conservation (Liu et al 2022). Data obtained in landscape genetics analyses are intended to inform the conservation and management of the target species (Storfer et al 2007 SCoT molecular markers are based on the short conserved region anking the ATG start codon in plant genes (Collard and Mackill 2009), and targets the coding sequence in the genome, mostly the open reading frames (ORFs), which reveals the relationship between ampli cation results and phenotype (Li and Quiros 2001).…”