Extremely low genetic variability and highly structured local populations of Arabidopsis thaliana at higher latitudes

The genetic diversity and population structure of Arabidopsis thaliana populations from Norway were studied and compared to a worldwide sample of A. thaliana in order to investigate the demographic history and elucidate possible colonization routes of populations at the northernmost species limit. We genotyped 282 individuals from 31 local populations using 149 single nucleotide polymorphism (SNP) markers. A high level of population subdivision (FST = 0.85 ± 0.007) was found indicating that A. thaliana is highly structured at the regional level. Significant relationships between genetic and geographic distances were found, suggesting an isolation by distance mode of evolution. Genetic diversity was much lower and the level of linkage disequilibrium (LD) higher in populations from the north (65–68oN) compared to populations from the south (59–62oN); this is consistent with a northward expansion pattern. A neighbor-joining (NJ) tree showed that populations from northern Norway form a sep...

本研究针对挪威境内的拟南芥（Arabidopsis thaliana）种群开展遗传多样性与种群结构分析，并与全球拟南芥样本进行比对，旨在探究其种群历史动态，阐明该物种分布最北界种群的潜在定殖路径。研究采用149个单核苷酸多态性（single nucleotide polymorphism, SNP）标记，对来自31个本地种群的282个个体进行基因分型。结果显示种群分化程度极高（FST = 0.85 ± 0.007），表明拟南芥在区域尺度上具有显著的种群结构。同时检测到遗传距离与地理距离间存在显著相关性，提示其演化符合距离隔离模式。相较于南部种群（59°~62°N），北部种群（65°~68°N）的遗传多样性显著更低，连锁不平衡（linkage disequilibrium, LD）水平更高，这与北向扩张的演化模式相符。邻接法（Neighbor-Joining, NJ）系统发育树显示，挪威北部种群形成一个独立的分支……