Interspecific Gene Flow and Selective Sweeps in Picea wilsonii, P. neoveitchii and P. likiangensis

Abstract

Genome-wide single nucleotide polymorphism (SNP) markers were obtained by genotyping-by-sequencing (GBS) technology to study the genetic relationships, population structure, gene flow and selective sweeps during species differentiation of Picea wilsonii, P. neoveitchii and P. likiangensis from a genome-wide perspective. We used P. jezoensis and P. pungens as outgroups, and three evolutionary branches were obtained: P. likiangensis was located on one branch, two P. wilsonii populations were grouped onto a second branch, and two P. neoveitchii populations were grouped onto a third branch. The relationship of P. wilsonii with P. likiangensis was closer than that with P. neoveitchii. ABBA-BABA analysis revealed that the gene flow between P. neoveitchii and P. wilsonii was greater than that between P. neoveitchii and P. likiangensis. Compared with the background population of P. neoveitchii, the genes that were selected in the P. wilsonii population were mainly related to plant stress resistance, stomatal regulation, plant morphology and flowering. The genes selected in the P. likiangensis population were mainly related to plant stress resistance, leaf morphology and flowering. Selective sweeps were beneficial for improving the adaptability of spruce species to different habitats as well as to accelerate species differentiation. The frequent gene flow between spruce species makes their evolutionary relationships complicated. Insight into gene flow and selection pressure in spruce species will help us further understand their phylogenetic relationships and provide a scientific basis for their introduction, domestication and genetic improvement.

Adaptive divergence, historical population dynamics, and simulation of suitable distributions for Picea Meyeri and P. Mongolica at the whole-genome level

“…With P. meyeri as the reference, genes related to stomatal regulation, such as KIN10A [ 82 ]; drought or cold stress, such as SRP , RGGA , and HXK2 [ 83 – 85 ]; and vascular plant seed germination and fruit ripening, such as PME [ 86 ], were found in P. mongolica , indicating that these selectively swept genes enable better adaptation to sandy environments and contributed to its evolution into an independent species within the genus Picea . Other researchers have also identified genes related to stomatal regulation, flowering (in angiosperms), and stress resistance among the genes showing evidence of selective sweeps in P. asperata , P. crassifolia , P. wilsonii , and P. koraiensis [ 58 , 87 , 88 ]. Throughout history, the habitat of the genus Picea has undergone significant changes due to geological events and climate fluctuations [ 89 ], resulting in new selection pressures.…”