Genetic analysis of the peatmoss Sphagnum cribrosum (Sphagnaceae) indicates independent origins of an extreme infra-specific morphology shift

Within Sphagnum cribrosum, a dioicous aquatic peatmoss, a unique morphological variant (the “waveform”), found at only two lakes in North Carolina, has a branching architecture that is extremely differentiated from anything otherwise known in Sphagnum, though the plants are microscopically indistinguishable from S. cribrosum. At one site where the two morphologies co-occur, sixty years of field observations demonstrate the persistence of each morphology, even where the two forms grow intermixed. We conducted a reciprocal transplant experiment in which waveform and normal plants maintained their divergent morphologies for eight months. We sampled populations throughout the range and conducted genetic and phylogenetic analyses with microsatellite markers and DNA sequences to investigate the genetic context of the waveform morphology within S. cribrosum. Haplotype networks from DNA sequences showed the two waveform populations are separated by 11 substitutions across three loci. Microsatel...

在皱叶泥炭藓（Sphagnum cribrosum）——一种雌雄异株的水生泥炭藓——中，存在一种独特的形态变种（“波形型（waveform）”），该变种仅在北卡罗来纳州的两个湖泊中被发现。其分枝结构与泥炭藓属迄今已知的所有类群均存在显著分化，但在显微形态下与皱叶泥炭藓无法区分。在两种形态共存的其中一个采样点，长达60年的野外观测记录表明，即便两类群混生，各自的形态特征仍能稳定维持。我们开展了互惠移植实验（reciprocal transplant experiment），结果显示波形型与正常型植株在8个月内仍保持其分化的形态特征。我们对该物种分布范围内的种群进行了系统采样，并利用微卫星标记（microsatellite markers）与DNA序列开展遗传与系统发育分析，以探究波形型变种在皱叶泥炭藓中的遗传背景。来自DNA序列的单倍型网络（haplotype networks）分析显示，两个波形型种群在3个基因座（loci）上存在11个替换位点。