Kim Seung-Chul
Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
J Hered. 2007 Jul-Aug;98(4):293-9. doi: 10.1093/jhered/esm052. Epub 2007 Jul 10.
As an initial step to mapping quantitative trait loci for species differences and adaptive radiation of insular endemics in Macaronesia, a genetic linkage map was constructed from an intergeneric backcross between Lactucosonchus webbii and Sonchus radicatus, core members of the tree lettuces in the Macaronesian Islands. A total of 152 amplified fragment length polymorphism markers were mapped into 10 major and 3 minor linkage groups for a total map length of 644 cM with an average distance of 4.53 cM for the 10 major groups. The genetic linkage map length is considerably less than the estimated, and this may reflect incomplete genomic coverage in the current study or reduced recombination, which is a common feature of maps for hybrids of divergent taxa. Segregation distortion occurred in 34% of the mapped markers, and they were located primarily in 4 linkage groups. Segregation distortion in the current BC(1) intergeneric population is slightly lower than average (40%) for BC(1) interspecific populations. This level of segregation distortion implies that unlike what we normally assume no to few reproductive barriers, oceanic island plant taxa do exhibit some degree of postmating reproductive isolation.
作为对马卡罗尼西亚群岛岛屿特有物种的物种差异和适应性辐射进行数量性状基因座定位的第一步，构建了一个遗传连锁图谱，该图谱来自马卡罗尼西亚群岛叶用莴苣核心成员韦伯乳苣和裂叶苦苣之间的属间回交。总共152个扩增片段长度多态性标记被定位到10个主要连锁群和3个次要连锁群中，总图长为644厘摩，10个主要连锁群的平均距离为4.53厘摩。遗传连锁图谱的长度明显小于估计值，这可能反映了当前研究中基因组覆盖不完整或重组减少，这是不同分类群杂种图谱的一个共同特征。34%的定位标记出现了分离畸变，它们主要位于4个连锁群中。当前BC(1)属间群体中的分离畸变略低于BC(1)种间群体的平均水平(40%)。这种分离畸变水平意味着，与我们通常认为没有或几乎没有生殖障碍不同，大洋岛屿植物类群确实表现出一定程度的交配后生殖隔离。
