Data from: Homogenization of populations in the wildflower Texas bluebonnet (Lupinus texensis)

Wildflowers seeds are routinely spread along highways and thoroughfares throughout North America as part of federal beautification policy, but the genetic effect of the introduction of these cultivated populations on wild populations of the same species is unknown. Interbreeding may occur between these seeded and wild populations, resulting in several possible outcomes. Here we sample 187 individuals in 12 matched pairs of neighboring wild and seeded populations of the Texas bluebonnet (Lupinus texensis), a species popular in commercially available wildflower seed mixes used by both the Texas Department of Transportation and the public. We use genotyping by sequencing to identify 11,741 genome-wide single nucleotide polymorphisms, as well as a smaller number of SNPs from the chloroplast genome, to analyze population structure and genetic diversity within and between the populations. We find a striking lack of population structure both between wild and seeded populations and amongst wild populations. STRUCTURE analyses indicate that all populations are apparently panmictic. This pattern may be explained by extensive swamping of wild populations by seeded germplasm and increased dispersal of semi-domesticated seed across this species’ core native range by humans. We discuss the possible negative and positive ramifications of homogenization on the evolutionary future of this popular wildflower species.

作为北美联邦美化政策的常规举措，野花种子常被播撒于全境公路与干道沿线，但此类栽培种群的引入对同一物种的野生种群造成的遗传效应仍未明确。播撒种群与野生种群间可能发生杂交，进而产生多种潜在结果。本研究针对德克萨斯羽扇豆（Lupinus texensis）——一种在得克萨斯州交通部门及民众所用商用野花种子混合物中广受欢迎的物种——的12对匹配的相邻野生种群与播撒种群，共采集187个个体样本。我们采用测序分型（genotyping by sequencing）技术，鉴定出11741个全基因组范围的单核苷酸多态性（single nucleotide polymorphisms, SNPs），以及少量叶绿体基因组SNPs，以此分析种群内与种群间的群体结构及遗传多样性。研究结果显示，野生种群与播撒种群之间，以及野生种群内部均未呈现显著的群体分化。STRUCTURE群体结构分析表明，所有种群均表现为典型的泛交群体。该格局可通过两方面得到解释：一是播种种质对野生种群的广泛遗传渐渗，二是人类活动使得该物种原生分布区内半驯化种子的扩散程度大幅提升。我们探讨了遗传同质化对这一广受欢迎的野生花卉物种进化前景可能带来的正负两方面影响。