Ferris C, Oliver R P, Davy A J, Hewitt G M
School of Biological Sciences, University of East Anglia, Norwich, Norfolk, UK.
Mol Ecol. 1993 Dec;2(6):337-44. doi: 10.1111/j.1365-294x.1993.tb00026.x.
Glacial refugia and postglacial migration are major factors responsible for the present patterns of genetic variation we see in natural populations. Traditionally postglacial history has been inferred from fossil data, but new molecular techniques permit historical information to be gleaned from present populations. The chloroplast tRNA(Leu1) intron contains regions which have been highly conserved over a billion years of chloroplast evolution. Surprisingly, in one of these regions which has remained invariant for all photosynthetic organisms so far studied, we have found intraspecific site polymorphism. This polymorphism occurs in two European oaks, Quercus robur and Q. petraea, indicating hybridisation and introgression between them. Two distinct chloroplast types occur and are distributed geographically as eastern and western forms suggesting that these oaks are each derived from at least two separate glacial refugia.
冰期避难所和冰期后迁移是导致我们在自然种群中看到的当前遗传变异模式的主要因素。传统上，冰期后的历史是从化石数据推断出来的，但新的分子技术使我们能够从当前种群中收集历史信息。叶绿体tRNA(Leu1)内含子包含在超过十亿年的叶绿体进化过程中高度保守的区域。令人惊讶的是，在迄今为止所有已研究的光合生物中都保持不变的其中一个区域，我们发现了种内位点多态性。这种多态性出现在两种欧洲栎树，即欧洲栓皮栎和无梗花栎中，表明它们之间存在杂交和基因渗入。出现了两种不同的叶绿体类型，并在地理上以东部和西部形式分布，这表明这些栎树各自至少起源于两个独立的冰期避难所。
