竞争力增强进化假说(Evolution of Increased Competitive Ability,EICA)认为入侵植物在入侵地由于天敌逃逸导致对天敌防御投入降低而增加生长和繁殖等投入。然而,EICA假说所预测防御能力的进化主要集中在防御的组成抗性方面,而从诱导...竞争力增强进化假说(Evolution of Increased Competitive Ability,EICA)认为入侵植物在入侵地由于天敌逃逸导致对天敌防御投入降低而增加生长和繁殖等投入。然而,EICA假说所预测防御能力的进化主要集中在防御的组成抗性方面,而从诱导抗性和耐受性的角度进行的验证还很有限,并且忽视了生境资源可利用性对植物防御策略的影响。本研究采用同质园实验比较了喜旱莲子草(Alternanthera philoxeroides)原产地(阿根廷)和入侵地(美国)各9个种群,在高、低养分和有、无专食性天敌取食处理下的防御相关功能性状(比茎长、根冠比)及其对天敌取食的诱导反应,以及它们与植物适合度相关指标的关系。结果表明:入侵地种群具有较高的总生物量(+14.7%)、较低的比茎长(防御钻茎化蛹天敌的重要指标,-27.5%),暗示其个体大小增加而防御投入降低,符合EICA假说的预测。入侵地种群耐受性与原产地种群没有显著差异。在高养分下,入侵地种群的比茎长对专食性天敌取食的诱导反应显著增加,且与总生物量呈显著正相关。这些结果表明,相比原产地种群,入侵地种群具有更高的生物量,对专食性天敌的组成抗性降低,且在高养分下对专食性天敌的诱导抗性增加,推测生境的养分富集可能会降低喜旱莲子草的生物防治效果。展开更多
根据DNA核苷酸组分的动态变化规律将遗传密码的传统排列按密码子对GC和嘌呤含量的敏感性进行了重排.新密码表可划分为2个半区(或1/2区)和4个四分区(或1/4区).就原核生物基因组而言,当GC含量增加时,物种蛋白质组所含的氨基酸倾向于使用G...根据DNA核苷酸组分的动态变化规律将遗传密码的传统排列按密码子对GC和嘌呤含量的敏感性进行了重排.新密码表可划分为2个半区(或1/2区)和4个四分区(或1/4区).就原核生物基因组而言,当GC含量增加时,物种蛋白质组所含的氨基酸倾向于使用GC富集区和嘌呤不敏感半区所编码的氨基酸,它们均使用四重简并密码,对DNA序列的突变具有相对鲁棒性(Robustness).当GC含量降低时,大多数密码子处于AU富集区和嘌呤敏感半区,这个区域编码的氨基酸具有物理化学性质的多样性.因为当密码子第三位核苷酸(CP3)在嘌呤和嘧啶之间发生转换时,密码子所编码的氨基酸也倾向于发生变化.关于遗传密码的进化存在多种假说,包括凝固事件假说、共进化假说和立体化学假说等,每种假说均试图解释遗传密码所表现出来的某些化学和生物学规律.基于遗传密码的物理化学性质、基因组变异的规律和相关的生物学假说,本研究提出了遗传密码分步进化假说(The Stepwise Evolution Hypothesis for the Genetic Code).在人们推断的最原始的RNA世界里,原初(Primordial)遗传密码从只能识别嘌呤和嘧啶开始,编码一个或两个简单而功能明确的氨基酸.由于胞嘧啶C的化学不稳定性,最初形成的遗传密码应该仅仅由腺嘌呤A和尿嘧啶U来编码,却可得到一组7个多元化的氨基酸.随着生命复杂性的增加,鸟嘌呤G从主载操作信号的功能中释放出来,再伴随着C的引入,使遗传密码逐步扩展到12,15和20个氨基酸,最终完成全部进化步骤.遗传密码的进化过程同时也伴随以蛋白质为主体的分子机制和细胞过程的进化,包括氨酰tRNA合成酶(AARS)从初始翻译机器上的脱离、DNA作为信息载体而取代RNA以及AARS和tRNA共进化等基本过程.分子机制和细胞过程是生命的基本组成元件,它们不但自己不断地趋于完善,也促使生命体走着不尽相同的道路,或�展开更多
Aims Field and common garden comparisons are commonly performed to test the rapid evolution of increased vigor in introduced plant populations.Latitudinal dines in phenotypic traits can obscure such evolutionary infer...Aims Field and common garden comparisons are commonly performed to test the rapid evolution of increased vigor in introduced plant populations.Latitudinal dines in phenotypic traits can obscure such evolutionary inferences,particularly when native or introduced populations are distributed across large geographic ranges.We tested whether the latitudinal dines influence comparisons between introduced and native populations of Senecio vulgaris.Methods Senecio vulgaris is native to Europe but has been introduced in northeastern and southwestern China.To evaluate the performance in terms of growth and reproduction between native European populations and introduced Chinese populations,we compared plant height,number of branches and number of capitula in field populations in native and introduced ranges and in a common garden in Switzerland.Important Findings The introduced Chinese populations performed better than the native European populations in the field in terms of plant height and number of capitula,which was consistent with the prediction of the evolution of the increased competitive ability(EICA)hypothesis.The Chinese populations produced more capitula than the European populations when the latitudinal cline was considered in the common garden comparison.When we compared the traits of the northeastern Chinese,southwestern Chinese and European populations in both the field and common garden,the northeastern Chinese populations,at latitudes similar to those of the European populations,exhibited greater plant size and more capitula than the European populations in both the field and common garden.However,the southwestern Chinese populations,at latitudes much lower than those of the European populations,did not perform better than the native populations in terms of reproduction.In conclusion,our results suggest that latitudinal dines in phenotypic traits should be considered in field and common garden comparisons when introduced populations are geographically structured.展开更多
文摘根据DNA核苷酸组分的动态变化规律将遗传密码的传统排列按密码子对GC和嘌呤含量的敏感性进行了重排.新密码表可划分为2个半区(或1/2区)和4个四分区(或1/4区).就原核生物基因组而言,当GC含量增加时,物种蛋白质组所含的氨基酸倾向于使用GC富集区和嘌呤不敏感半区所编码的氨基酸,它们均使用四重简并密码,对DNA序列的突变具有相对鲁棒性(Robustness).当GC含量降低时,大多数密码子处于AU富集区和嘌呤敏感半区,这个区域编码的氨基酸具有物理化学性质的多样性.因为当密码子第三位核苷酸(CP3)在嘌呤和嘧啶之间发生转换时,密码子所编码的氨基酸也倾向于发生变化.关于遗传密码的进化存在多种假说,包括凝固事件假说、共进化假说和立体化学假说等,每种假说均试图解释遗传密码所表现出来的某些化学和生物学规律.基于遗传密码的物理化学性质、基因组变异的规律和相关的生物学假说,本研究提出了遗传密码分步进化假说(The Stepwise Evolution Hypothesis for the Genetic Code).在人们推断的最原始的RNA世界里,原初(Primordial)遗传密码从只能识别嘌呤和嘧啶开始,编码一个或两个简单而功能明确的氨基酸.由于胞嘧啶C的化学不稳定性,最初形成的遗传密码应该仅仅由腺嘌呤A和尿嘧啶U来编码,却可得到一组7个多元化的氨基酸.随着生命复杂性的增加,鸟嘌呤G从主载操作信号的功能中释放出来,再伴随着C的引入,使遗传密码逐步扩展到12,15和20个氨基酸,最终完成全部进化步骤.遗传密码的进化过程同时也伴随以蛋白质为主体的分子机制和细胞过程的进化,包括氨酰tRNA合成酶(AARS)从初始翻译机器上的脱离、DNA作为信息载体而取代RNA以及AARS和tRNA共进化等基本过程.分子机制和细胞过程是生命的基本组成元件,它们不但自己不断地趋于完善,也促使生命体走着不尽相同的道路,或�
基金This work was financially supported by the National Natural Science Foundation of China(30670359 and 31700326)the 111 project(B13008)Beijing Advanced Innovation Program for Land Surface Science and the State Key Laboratory of Earth Surface Processes and Resource Ecology.
文摘Aims Field and common garden comparisons are commonly performed to test the rapid evolution of increased vigor in introduced plant populations.Latitudinal dines in phenotypic traits can obscure such evolutionary inferences,particularly when native or introduced populations are distributed across large geographic ranges.We tested whether the latitudinal dines influence comparisons between introduced and native populations of Senecio vulgaris.Methods Senecio vulgaris is native to Europe but has been introduced in northeastern and southwestern China.To evaluate the performance in terms of growth and reproduction between native European populations and introduced Chinese populations,we compared plant height,number of branches and number of capitula in field populations in native and introduced ranges and in a common garden in Switzerland.Important Findings The introduced Chinese populations performed better than the native European populations in the field in terms of plant height and number of capitula,which was consistent with the prediction of the evolution of the increased competitive ability(EICA)hypothesis.The Chinese populations produced more capitula than the European populations when the latitudinal cline was considered in the common garden comparison.When we compared the traits of the northeastern Chinese,southwestern Chinese and European populations in both the field and common garden,the northeastern Chinese populations,at latitudes similar to those of the European populations,exhibited greater plant size and more capitula than the European populations in both the field and common garden.However,the southwestern Chinese populations,at latitudes much lower than those of the European populations,did not perform better than the native populations in terms of reproduction.In conclusion,our results suggest that latitudinal dines in phenotypic traits should be considered in field and common garden comparisons when introduced populations are geographically structured.
