兰州大学机构库 >生命科学学院
同倍体杂交物种紫果云杉生态位分化的生理生态机制
Alternative TitleThe ecophysiological mechanisms of ecological divergence of homoploid hybrid species Picea purpurea
王婧如
Thesis Advisor赵长明
2018-10-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Degree Discipline生态学
Keyword同倍体杂交物种 生态位分化 超亲分离 水分关系 耐冻性 木质部栓塞化 光质 光合作用 气孔特征
Abstract同倍体杂交物种形成即没有发生染色体数目变化的杂交物种形成过程,多见于被子植物,而裸子植物中鲜有。杂交物种与亲本种生态位分化的产生是该物种形成发生的重要前提,且前者超亲性状的产生起到关键作用。紫果云杉(Picea purpurea)是最近发现的同倍体杂交针叶物种,分子证据表明其起源于丽江云杉(P. likiangensis)和青扦(P. wilsonii)的自然同倍体杂交作用,且占据了青藏高原东北部高纬度高海拔极端生境。与低海拔相比,高海拔具有低温、低CO2浓度和短波光比率增大的特点。冬季低温常造成叶片脱水并引发木质部栓塞化的形成,低CO2浓度和短波光则直接影响了植物的气体交换和气孔发育。迄今,关于此类生理生态过程在同倍体杂交物种中是否发生超亲分离并促进其对极端新生境的占领仍然缺乏研究。本文以同倍体杂交物种紫果云杉和其亲本种为材料,量化了三者的生态位差异,预测了其在未来气候变化下分布区的变化。在此基础上,本文亦从叶片光系统耐低温能力、水分关系和茎与叶(即一年生枝条和当年生枝条)的木质部抗栓塞化能力、在不同光质和CO2浓度下的气体交换响应和气孔解剖等方面系统地比较了紫果云杉与亲本种间的生理和形态差异,以期揭示紫果云杉占领高海拔极端生境的生理生态学机制。本文主要研究结果如下:(1)生态位差异分析结果表明紫果云杉生境的水热条件与亲本种间均存在显著差异。对水分条件而言, 尽管紫果云杉生境的最冷季与最暖季降雨量居于亲本种之间,但其生境土壤湿度显著高于两亲本种;对热量条件而言,紫果云杉生境的最冷月最低温显著低于两亲本种,且地面结霜频率显著高于两亲本种。对三个云杉物种的未来潜在分布区模拟显示,紫果云杉仅在RCP2.6下2080s的潜在分布面积与当前相比略有缩减(约5%),而在此情景下2050年的潜在分布区面积和其余两个情景下2050s和2080s的潜在分布面积高于当前分布区面积,表现出扩张趋势。(2)水分生理研究结果表明紫果云杉的饱和膨压渗透势、膨压丧失点水势、茎丧失12%导水率时的木质部水势和茎最大导水率皆显著低于其亲本种。此外,紫果云杉的茎和叶丧失50%导水率时的木质部水势以及茎叶的导水安全范围与青扦相近,且都显著低于丽江云杉。针叶低温响应实验显示引起紫果云杉最大光化学效率(Fv/Fm)下降50%的温度显著低于其亲本种。光质光合响应实验表明,紫果云杉在蓝光和红光下的表观量子效率和最大光合效率远高于其亲本种,且在所有三种光质下都表现出高的瞬时水分利用效率和低CO2浓度时高的气孔导度值。其他性状中,与亲本种相比,紫果云杉亦表现出高的叶片叶绿素含量、长的保卫细胞长度和低的气孔线密度。综上,本研究明确了同倍体杂交物种紫果云杉与其亲本种生态位的环境差异,即高土壤湿度和冬季低温是紫果云杉与其亲本种产生生态位分化的主要因子;且在未来温度显著增加背景下,紫果云杉在未来2050s和2080s潜在分布区面积将显著增加,推测其在未来将发挥更重要的生态安全屏障作用。同时,紫果云杉的光系统耐冻性、细胞耐脱水能力、对不同光质和低CO2浓度的气体交换以及气孔解剖特征等皆呈现了超亲分离现象,这些性状的超亲作用促进了紫果云杉对高海拔生境的成功侵占。
Other AbstractHomoploid hybrid speciation, characterized by hybrid speciation without a change in chromosome number, is well known in angiosperms but rare in gymnosperms. The generation of ecological divergence between the hybrid species and its progenitors is the precondition of this kind of speciation, and the production of transgressive phenotypes within the hybrids has play an important role. Molecular evidence demonstrated that Picea purpurea originated from the homoploid hybridization between P. likiangensis and P. wilsonii and it is distributed in northeastern Qinghai-Tibet Plateau at higher altitudes and latitudes than its parental species. High altitude regions are usually characterized by low air temperature and atmospheric CO2 concentrations, as well as strong solar radiation with a large fraction of shortwave radiation compare to the low altitude. Generally, plants were suffering from the occurrence of cell dehydration and xylem embolism induced by freezing-stress in winter, whereas the gas exchange and stomatal development were affected by the low atmospheric CO2 concentrations and shortwave radiation. So far, researches on whether these ecophysiological traits had been transgressive segregation in the hybrid species and thus promoted it occupy the novel extreme habitat were still lack. In this paper, we analyzed the environmental divergence between the homoploid hybrid species P. purpurea and its progenitors, and predicted the change of their potential distribution under climate change. Besides, we also compared the frost tolerance of photosystem stability, water relations, xylem resistance to dysfunction of leaves (current-year twigs) and stems (annual shoots), leaf gas exchange properties at two level of CO2 concentration (Ca: 200 and 400 μmol mol-1), light responsive curves of photosynthesis under three light qualities (blue, red, red & blue) and stomatal anatomical for three Picea species with the aim of reveal the mechanisms of P. purpurea colonized the novel extreme habitat on the basis of ecophysiology. The main results were listed below:(1) The results of ecological divergence indicated that the water and heat availability for P. purpurea were all significantly different from its parental species. That is, despite of the precipitation of coldest and warmest quarter of P. purpurea was intermediate between its progenitors, its soil moisture was significantly higher than them; the min temperature of coldest month of P. purpurea was significantly lower than that of its parental species, and the ground-frost frequency of P. purpurea was inversely higher than that of its progenitors. Furthermore, results from simulation-based estimates revealed that the potential distribution area for P. purpurea would decrease (about 5%) in the 2080s only under RCP2.6, while in the 2050s of this scenario and under other two scenarios, its distributional area in two time periods were higher than the current.(2) The results of water physiological showed that P. purpurea had significantly lower osmotic potential at full turgor, water potential at turgor loss point, water potential at 12% loss of conductance of stem and the maximum hydraulic conductance of stem than its parental species. In contrast, the leaf and stem xylem pressure inducing 50% loss of hydraulic conductivity (leaf Ψ50 and stem Ψ50, respectively) and hydraulic safety margin in leaf Ψ50, stem Ψ50 in P. purpurea showed no significant difference with those of P. wilsonii, but significantly larger values than those of P. likiangensis. The freezing temperature response experiment indicated that the temperature causing a 50% reduction in initial Fv/Fm of P. purpurea was apparently lower than that of its parental species. As for the results of photosynthesis responsive curves under different light qualities, P. purpurea was demonstrated that quantum yield of CO2 assimilation (φ) and maximum CO2 assimilation rate (Amax) were higher than its progenitors under blue and red light. P. purpurea also exhibited higher stomatal conductance at low CO2 concentrations and instantaneous water use efficiency under all light qualities, have greater leaf pigments content, longer guard cell length and lower linear stomatal density relative to its progenitors.In summary, this paper demonstrated the environmental divergence between the homoploid hybrid species P. purpurea and its parental species: i.e. the higher soil moisture and the low temperature in the winter were the key factors that driving the ecological divergence in P. purpurea from its progenitors and the potential distribution area of P. purpurea would significantly increase in the 2050s and 2080s. This suggested that P. purpurea would play an important role in the ecological security barrier in the future. The results of ecophysiological and morphological research indicated that the frost tolerance of photosystem stability, cell dehydration tolerance, gas exchange properties under different light qualities and low CO2 concentration and stomatal anatomical characters in P. purpuea were superior to its parental species. These traits may enhance the physiological fitness of P. purpurea and facilitated its colonization and successful establishment to alpine habitats.
Pages90
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/341872
Collection生命科学学院
Affiliation生命科学学院
First Author AffilicationSchool of Life Sciences
Recommended Citation
GB/T 7714
王婧如. 同倍体杂交物种紫果云杉生态位分化的生理生态机制[D]. 兰州. 兰州大学,2018.
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