不同花型姐妹种雪地报春和突厥报春繁育系统的演化研究

Research about new species evolution process has fascinated hundreds of plant evolutionary ecologists. Although, distyly species is main group of angiosperm flower morph evolution the most of distyly species are still poorly understood for their origin, evolution, adaptation and maintenance. The comparative study on two different floral morph sister species breeding system plays an important role for investigation on origin and evolution in homostyly from distyly morph. Primula nivalis and P. turkestanica are two different floral morph sister species viz. homostyly and distyly of Primula, and grow only in northern Xinjiang, China. The biological characters, population characters, and growth area are different for these species in natural populations. Present study aimed to study on evolution of homostyly species from distyly and determination of the floral differenciation in sister species. We hypothesized that the evolution of homostyly P. turkestanica, when distally species of P. nivalis was migrated to a new population or breeding process and the changes in ecological factors (altitude or pollinator) associated to the evolution of P. nivalis breeding systems, were the major factor for speciation of secondary homostyly P. turkestanica. To test this hypothesis, the effects of ecological factors on differentiations of floral character, population genetic structures, pollination, and mating system will be quantified for two sister species of Primula in Xinjiang. At the completion of this study, we will ascertain the dynamic breeding system and evolution history of two different floral morph sister speceis. Moreover, we will explore the ecological adaptive strategies and effect of change of population structure dependent breeding system on evolution prosees of these two sister speceis. Our overall goal is to develop a general theoretical basis for evolution of distlly speceis and determination of the floral differenciation of angiosperm species. ..

二型花柱作为被子植物花性器官演化和物种形成过程中的主要问题已引起进化生态学领域的高度关注，但二型花柱植物的起源和演化十分不清楚。因此，不同花型近缘种繁育系统的比较研究，对揭示二型花柱物种起源和演化趋势具有重要的意义。雪地报春(Primula nivalis)和突厥报春(P. turkestanica)是在我国仅分布于新疆的不同型姐妹种；二者在生物学特性、空间分布特点及生长微环境间存在差异。因此，我认为二型花柱雪地报春迁移到新居群或繁殖过程中，与居群海拔有关生态因子变化导致的繁育系统演化，可能是形成次生同型花柱突厥报春的主要因素。为验证该假设，本项目将通过对雪地报春和突厥报春的花部特征分化和居群遗传结构、传粉特性以及交配系统的比较研究。揭示这两物种在繁育系统特点上的异同点；探讨这些特点在二者演化过程中的作用，以期为全面揭示二型花柱植物繁育系统演化趋势并进一步探讨被子植物花分化机制提供理论依据

二型花柱是被子植物花器官演化和繁育系统进化的研究热点之一。二型花柱植物不同海拔居群繁育系统间的比较研究，对于揭示该类群植物的演化与环境的关系，具有重要的意义。.雪地报春 (Primula nivalis)是在新疆分布较广的二型花柱植物，该物种在不同海拔居群的生境、植株大小及结实率等特征上存在明显差异。本项目对雪地报春长、短花柱植株在不同海拔居群的表型比、植株和花的形态特征、传粉特性、交配方式、后代适合度及近交衰退机制等进行了比较研究，力图揭示该物种在不同生境中的繁殖对策和适应机制，从而探讨了这些特点在雪地报春花柱二型性演化过程中的作用。(1)生境异质性对雪地报春植株形态特征及资源分配具有一定的影响，存在异质生境导致的形态变异。两种表型植株在异质生境中表现出的形态变异程度间存在显著差异，其中长花柱植株的形态变异高于短花柱植株。在高海拔草原居群中长花柱植株比例高于短花柱植株。(2)比较草原和森林生态系统中的雪地报春居群，长花柱花形态特征间存在显著差异，但短花柱花形态特征间的差异不显著。高海拔草原居群中长花柱花的花冠筒长度、雄蕊长度、雌雄异位程度以及雌雄蕊空间位置是导致花性状差异显著的主要因素。(3)不同海拔居群的传粉者种类、访花频率以及传粉效率间存在显著差异。该物种长、短花柱花的花粉传递效率间存在显著差异，其中短花柱花的花粉传递效率随着海拔的上升而降低，而长花柱花的的花粉传递效率随着海拔的上升提高。雪地报春存在不同程度的自交亲和，其中长花柱花的自交亲和性与海拔间存在正相关性；但短花柱的自交亲和性与海拔间不存在显著相关性。(4) 在不同海拔居群中长花柱植株的结实率均高于短花柱植株。长花柱花产生种子的适合度高于短花柱花产生种子的适合度；短花柱花产生种子在萌发阶段的近交衰退系数随着居群海拔的上升而逐渐增高，但长花柱花产生种子在萌发阶段的近交衰退指数与居群海拔间不存在显著的差异。