Brennan Adrian C, Hiscock Simon J, Abbott Richard J
Department of Biosciences, University of Durham, South Road, Durham, UK.
School of Biology, University of St Andrews, St Andrews, Fife, UK.
AoB Plants. 2019 Jan 6;11(1):ply078. doi: 10.1093/aobpla/ply078. eCollection 2019 Feb.
A new homoploid hybrid lineage needs to establish a degree of reproductive isolation from its parent species if it is to persist as an independent entity, but the role hybridization plays in this process is known in only a handful of cases. The homoploid hybrid ragwort species, (Oxford ragwort), originated following the introduction of hybrid plants to the UK approximately 320 years ago. The source of the hybrid plants was from a naturally occurring hybrid zone between and on Mount Etna, Sicily. Previous studies of the parent species found evidence for multiple incompatibility loci causing transmission ratio distortion of genetic markers in their hybrid progeny. This study closes the hybridization triangle by reporting a genetic mapping analysis of the remaining two paired cross combinations between and its parents. Genetic maps produced from F mapping families were generally collinear but with half of the linkage groups showing evidence of genomic reorganization between genetic maps. The new maps produced from crosses between and each parent showed multiple incompatibility loci distributed across the genome, some of which co-locate with previously reported incompatibility loci between the parents. These findings suggest that this young homoploid hybrid species has inherited a unique combination of genomic rearrangements and incompatibilities from its parents that contribute to its reproductive isolation.
一个新的同倍体杂交谱系若要作为一个独立的实体持续存在，就需要与亲本物种建立一定程度的生殖隔离，但杂交在这一过程中所起的作用仅在少数案例中为人所知。同倍体杂交千里光物种（牛津千里光）大约在320年前随着杂交植物被引入英国而起源。这些杂交植物的来源是西西里岛埃特纳火山上 和 之间的一个自然杂交区。之前对亲本物种的研究发现了多个不相容位点，这些位点导致其杂交后代中遗传标记的传递率扭曲。本研究通过报告 与其亲本之间其余两个配对杂交组合的遗传图谱分析，闭合了杂交三角。从F作图群体产生的遗传图谱通常是共线的，但有一半的连锁群显示出遗传图谱之间基因组重组的证据。 与每个亲本杂交产生的新图谱显示，多个不相容位点分布在整个基因组中，其中一些与之前报道的亲本之间的不相容位点共定位。这些发现表明，这个年轻的同倍体杂交物种从其亲本那里继承了基因组重排和不相容性的独特组合，这些因素有助于其生殖隔离。
