Hybridization and polyploidy as drivers of continuing evolution and speciation in Sorbus
Hybridization and polyploidy as drivers of continuing evolution and speciation in Sorbus
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DOI：
10.1111/j.1365-294x.2010.04585.x
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发表时间：
2010-04-01
影响因子：
4.9
通讯作者：
Hiscock, Simon J.
中科院分区：
文献类型：
--
作者：
Robertson, Ashley;Rich, Timothy C. G.;Hiscock, Simon J.
种间杂交和多倍体是植物进化和物种形成的关键过程。新的杂种和多倍体分类群的命运取决于它们有性或无性繁殖的能力。染色体数目为奇数的杂种和异源多倍体通常是不育的，但有些是通过无性繁殖（营养繁殖或无融合生殖）建立的。这使得新的基因型通过将它们从基因流中分离出来而得以建立，并导致复杂的变异模式。花楸属是一个很好的例子，分类复杂性产生的杂交，多倍体和无融合生殖的综合影响。英国西南部的埃文峡谷是欧洲花楸属植物多样性最丰富的地区，在15种花楸属植物中，有3种是当地特有种，4种是当地特有的新杂交种。我们使用了核微卫星和叶绿体DNA标记相结合，调查这些花楸类群在埃文峡谷的进化关系。我们证实了推定的新类群的遗传身份，并表明，杂交涉及有性二倍体物种，主要是S。aria和S. torminalis和来自Aria亚属的多倍体兼性无融合生殖物种，负责产生这种生物多样性。重要的是，我们的数据表明，这种创造性的进化过程正在埃文峡谷内进行。因此，珍稀特有花楸类群的保护策略应该考虑峡谷内的所有花楸类群，必须努力保护这一进化过程，而不仅仅是它产生的单个稀有类群。
Interspecific hybridization and polyploidy are pivotal processes in plant evolution and speciation. The fate of new hybrid and polyploid taxa is determined by their ability to reproduce either sexually or asexually. Hybrids and allopolyploids with odd chromosome numbers are frequently sterile but some establish themselves through asexual reproduction (vegetative or apomixis). This allows novel genotypes to become established by isolating them from gene flow and leads to complex patterns of variation. The genus Sorbus is a good example of taxonomic complexity arising from the combined effects of hybridization, polyploidy and apomixis. The Avon Gorge in South-west Britain contains the greatest diversity of Sorbus in Europe, with three endemic species and four putative endemic novel hybrids among its 15 native Sorbus taxa. We used a combination of nuclear microsatellite and chloroplast DNA markers to investigate the evolutionary relationships among these Sorbus taxa within the Avon Gorge. We confirm the genetic identity of putative novel taxa and show that hybridization involving sexual diploid species, primarily S. aria and S. torminalis and polyploid facultative apomictic species from subgenus Aria, has been responsible for generating this biodiversity. Importantly our data show that this creative evolutionary process is ongoing within the Avon Gorge. Conservation strategies for the rare endemic Sorbus taxa should therefore consider all Sorbus taxa within the Gorge and must strive to preserve this evolutionary process rather than simply the individual rare taxa that it produces.