Reproductive isolation among two interfertile Rhododendron species:: low frequency of post-F1 hybrid genotypes in alpine hybrid zones
Reproductive isolation among two interfertile Rhododendron species:: low frequency of post-F1 hybrid genotypes in alpine hybrid zones
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DOI：
10.1111/j.1365-294x.2007.03643.x
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发表时间：
2008-02-01
影响因子：
4.9
通讯作者：
Abbott, Richard J.
中科院分区：
文献类型：
--
作者：
Milne, Richard I.;Abbott, Richard J.
喜酸的杜鹃花和碱性土壤的毛杜鹃花之间的杂交种出现在欧洲阿尔卑斯山的中等pH值的土壤上。材料从两个杂交区类似的500米，也附近的每个亲本物种的种群，进行了调查，存在/不存在的31个随机扩增多态性DNA标记，区分父母。根据形态学评价，材料包括51个推定的杂种，18个推定的R。ferrugineum和26个R.多毛类植物RAPD数据进行了分析，使用贝叶斯方法实施的程序NEWHYBRIDS，也通过主坐标分析。所有R. ferrugineum植物的检测得到了证实，然而，推定的R.在对多毛类植物个体进行检测时，2个肯定是杂交衍生物，11个可能是杂交衍生物。在所有的杂交衍生物中，约有一半被指定为F（1）或类似的类，否则回交到R。hirsutum似乎是常见的，而其他杂交类是罕见的，回交到R。ferrugineum可能缺席。尽管如此，人工产生的F-2类种子和每个方向的回交显示出比一个亲本更大的生活力（R。hirsutum）。从R.从形态学上看似乎只含有R的种群中也检测到了ferrugineum。多毛植物因此，回交的方向可能是高度不对称的杂交区内，造成单向基因流从R。ferrugineum转化为R.多毛植物相反，回交到R的稀有性。ferrugineum、F（2）s及以后的杂种世代，可能是由于物候效应和生境介导的选择作用，限制了基因向R.铁锈
Hybrids between the acid-loving species Rhododendron ferrugineum and the basic soil species Rhododendron hirsutum occur on soils of intermediate pH in the European Alps. Material from two hybrid zones similar to 500 m apart, and also nearby populations of each parent species, was surveyed for presence/absence of 31 random amplified polymorphic DNA markers that distinguish parents. Based on morphological assessment, the material comprised 51 putative hybrids, 18 putative R. ferrugineum individuals and 26 putative R. hirsutum plants. RAPD data were analysed using a Bayesian approach implemented by the program NEWHYBRIDS, and also by principal coordinates analysis. The identity of all R. ferrugineum plants examined was confirmed; however, of the putative R. hirsutum individuals examined, two were certainly and 11 possibly hybrid derivatives. Among all hybrid derivatives examined, about half were designated as F(1)s or a similar class, otherwise backcrosses to R. hirsutum appeared to be common whereas other hybrid classes were rare and backcrosses to R. ferrugineum possibly absent. Despite this, artificially generated seed of F-2 class and backcrosses in each direction showed greater viability than one parent (R. hirsutum). Introgression from R. ferrugineum was also detected in a population that from morphology appeared to contain only R. hirsutum. Hence, the direction of backcrossing might be highly asymmetric within hybrid zones, causing unidirectional gene flow from R. ferrugineum into R. hirsutum. Conversely, the rarity of backcrosses to R. ferrugineum, F(2)s and later hybrid generations, which might be due to phenology effects and habitat-mediated selection, could play a part in restricting gene flow towards R. ferrugineum.