极小种群野生植物毛脉杜鹃的自然杂交起源研究

	极小种群野生植物毛脉杜鹃的自然杂交起源研究; The natural hybridization origin of Rhododendron pubicostatum T. L. Ming，a plant species with extremely small populations (PSESP)
	张雪梅
导师	孙卫邦
摘要	Although the role of natural hybridization in adaptive evolution and speciation has been widely concerned, research on the formation and maintenance of PSESP (Plant Species with Extremely Small Populations) related with the natural hybridization was rarely reported. One of the most prominent problems is that interspecific hybridization can produce a very extremely small number of hybrid offspring, which may be misjudged as PSESP for taking the urgent conservation actions. Therefore, for plants with frequently natural hybridization, analyzing the relationship between natural hybridization and the formation and maintenance of the "extremely small populations" is a prerequisite for the species conservation Rhododendron pubicostatum (Ericaceae) was evaluated as endangered (EN) in The Red List of rhododendrons and as vulnerable (VU) in the Threatened Species List of China’s Higher Plants. And it’s also ranked as PSESP requiring urgent conservation as its’ total mature plants are less than 5000 individuals. In fact, the morphological characters of R. pubicostatum are “intermediates” of the two overlapped distrtibuted species of R. bureavii and R. sikangense var. exquisitum，and also the period of blooming of the three species are almost same. Thus, R.pubicostatum might be the natural hybrids between the two species. Based on the comprehensive studies on morphology, molecular biology and reproductive ecology of R. pubicostatum, R. bureavii and R. sikangense var. exquisitum，we further revealed the fact reality that R. pubicostatum is a natural hybrids of the two species. The pre-zygotic isolation of the natural hybrid between R. bureavii and R. sikangense var. exquisitum is incomplete, but the pre-zygotic isolation is stronger than the post-zygotic isolation. Geographic isolation plays a leading role, and the difference in distribution space significantly reduces interspecific hybridization. In addition to geographical isolation, that is, the calculation of the reproductive isolation intensity between the sympatry species, the isolation mediated by pollinators dominates the prezygotic isolation. To summarize, all evidences based on the studies of morphology, molecular biology, reproductive biology/ecology, as well as reproductive isolation intensity indicate that R. pubicostatum is not a taxonomically indepent taxa and it’s truly a natural hybrids. Thus, R. pubicostatumis is not necessary to be a priority of PSESP for urgent rescuing conservation. However, it provides’ the valuable germplasm resource for further utilizing and breeding of ornamental cultivars.
	2020-08
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/74219
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	张雪梅. 极小种群野生植物毛脉杜鹃的自然杂交起源研究, The natural hybridization origin of Rhododendron pubicostatum T. L. Ming，a plant species with extremely small populations (PSESP)[D],2020.

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