土壤水分对再生稻头季后期稻株光合和呼吸生理的影响研究   总被引：2，自引：0，他引：2  

吴文彬  黄友钦 《西南大学学报(自然科学版)》1995,17(6):486-488

再生稻头季稻生育后期适当降低土壤含水量，可延缓稻株的衰老，减缓光合强度，呼吸强度和叶绿素含下降速度，促进再生芽的生长发育，为再生稻高产奠定物质基础。  相似文献   

如何做好林木引种工作   总被引：2，自引：0，他引：2  

贾禾 《山西林业科技》1997,(2):39-41

简要地讨论了林木引种的原则、方法及应注意的问题  相似文献   

超线性发展方程组整体弱解的存在性与鼓涨     

徐海祥 《湖南农业大学学报(自然科学版)》1992,19(1)

In this paper, we consider the initial boundary value problem with the homogeneous boundary condition for the system of evolution equations. By using the stable set, we obtain the existence of global weak solution and the Blow-up of local weak solution fo  相似文献   

Charles Darwin, ichthyology and the species concept     

Daniel Pauly 《Fish and Fisheries》2002,3(3):146-150

This contribution presents the ichthyological writings of Charles Darwin (1809–1882), by periods, viz. ‘the years prior to the voyage of the Beagle’ (about 1825–1830); ‘the Beagle years’ (1831–1836); ‘from the return of the Beagle to the Foundation of Origin’ (1837–1844); and ‘the mature Darwin’ (1845–1882). Overall, this material covers 45 000 words penned by Darwin, but represents only 0.7% of his lifetime output of about 6 million words, indicating a limited interest in fish. However, this sample, briefly described here, but analysed in great detail in a forthcoming volume on Darwin's Fishes, allows drawing inferences on Darwin's working style that were missed in conventional biographies. On the other hand, it is suggested, based on a close reading of the 6^th (1876) edition of Origin, that Darwin was not particularly interested in the theoretical issues now associated with the species concept, nor indeed with other levels of the Linnean system.  相似文献   

天牛防治法的演变及评述   总被引：1，自引：0，他引：1  

黄尔田  胡水元 《蚕桑通报》1998,29(2):11-12

本文对从古至今天牛防治方法的演变作了较为全面的论述,并对各种防治方法作了评价。  相似文献   

岱海湖盆未来10年环境演变趋势探讨   总被引：4，自引：0，他引：4  

刘清泗  李华章 《干旱区资源与环境》1998,12(1):44-51

本文在野外考察的基础上,对岱海湖心作了介形类、化学元素分析,并采用统计分析手段,探讨了环境变化的准周期和未来１０年演变趋势。本区短尺度环境演变以气候为主导因素,其变化主要与地球的天体运动准周期有关,不同尺度周期的叠加干扰和影响使气候变化将向凉干方向发展,但是干燥化的趋势将有比较明显的缓解。未来１０年气候变化的自然趋势将受到温室效应的一定影响。  相似文献   

Signatures of functional constraint at Fgfr1a Genes in schizothoracine fishes (Pisces: Cypriniformes): The dermal skeleton variation adapted to high‐altitude environments          下载免费PDF全文

Xinyi GUO  Ling XIE  Xuze ZHANG  Yinfa JI  Juan CHEN  Bo PANG  Yongtao XU  Delin QI  Songchang GUO 《Integrative zoology》2016,11(2):86-97

Fishes harbor a huge resource of phenotypic diversity and are useful for understanding the genetic basis of morphological variation. However, it is difficult to transfer classical genetic mapping to most non‐model species. In this study, we performed a comparative sequence analysis of Fgfr1a to first interpret the evolution of this candidate scale‐loss gene in 15 schizothoracine fishes with various scale phenotypes. While considerable amino acid (AA) substitutions were observed, molecular evolution analysis indicates that the overall coding regions were subject to functional constraint. We also identified extra copies of Fgfr1a in 4 scale‐loss fishes and detected accelerated evolution in one AA substitution specific to these duplicates. We speculate that Fgfr1a had accumulated mutations in the ancestral lineage of scale‐loss schizothoracine fishes before experiencing duplication events, which was further followed by the diversification of species. In silico mutation analysis predicted deleterious effects of the mutations while no disruptive molecular mechanism was detected. Collectively, our results highlight the important role of Fgfr1a gene in the adaptive evolution of schizothoracine fishes during their radiation in the Qinghai‐Tibetan Plateau.  相似文献   

Population genome of the newly discovered Jinchuan yak to understand its adaptive evolution in extreme environments and generation mechanism of the multirib trait     

Daoliang LAN  Wenhui JI  Xianrong XIONG  Qiqi LIANG  Wenye YAO  Tserang-Donko MIPAM  Jincheng ZHONG  Jian LI 《Integrative zoology》2021,16(5):685-695

The adaptation and diversity of animals to the extreme environments of the Qinghai–Tibet Plateau (QTP) are typical materials to study adaptive evolution. The recently discovered Jinchuan yak population has many individuals with multiple ribs. However, little is known about this yak's origin, evolution, and the genetic mechanisms that formed its unique multirib trait. Here, we report a valuable population genome resource of the Jinchuan yak by resequencing the whole genome of 150 individuals. Population genetic polymorphism and structure analysis reveal that Jinchuan yak can be differentiated as a unique and original yak population among the domestic yak. Combined with geological change, the Jinchuan yak's evolutionary origin is speculated to be about 6290 years ago, which may be related to the unique geographical environment of the eastern edge of the QTP during this period. Compared with other domestic yaks, this new population has 280 positively selected genes. The genes related to skeletal function hold a considerable and remarkable proportion, suggesting that the specific skeletal characteristics have been enhanced in the adaptive evolution of Jinchuan yak in the extreme plateau environment. The genome-wide association study has revealed that TUBA8 and TUBA4A, the genes that regulate the cytoskeleton, are potential genes associated with the multirib trait. Our findings provide a basis to further understand the generation mechanism of the adaptive evolution of this new population in high-altitude extreme environments and the multivertebrate trait of domestic animals.  相似文献   

龙眼miR166家族的分子进化特性及时空表达分析     

林玉玲  张清林  曾友竞  陈晓慧  张梓浩  陈裕坤  赖钟雄 《园艺学报》2017,44(12):2285-2295

为了解miR166基因家族的分子进化特性及其在龙眼不同组织部位的表达规律,对龙眼miR166家族成员的成熟体和前体序列及其进化、前体二级结构预测、靶基因预测以及时空表达模式进行了分析。结果表明:龙眼miR166家族含有12条成熟体序列和7个前体序列(pre-miRNA)。Mfold预测显示pre-miR166家族7个成员的序列均能形成典型稳定的茎环二级结构,成熟序列的碱基保守性高,其他位置的则保守性减弱;它们的最小折叠自由能(ΔG)在–35.30~–83.30kal·mol~(-1)。系统发育进化树分析显示,龙眼pre-miR166家族与葡萄、碧桃的pre-miR166亲缘关系更为接近。靶基因预测显示,龙眼miR166基因家族靶基因包括同源异型域—亮氨酸拉链蛋白、三角状五肽重复结构蛋白、假定蛋白、DNA指导的RNA聚合酶Ⅲ亚单位RPC2、紫外线B受体等。实时荧光定量PCR显示,pre-miR166家族不同成员在龙眼生长发育进程中均有表达且表达模式不尽相同,提示其可能广泛参与龙眼各个器官的调控,且在功能上可能具有分工。  相似文献   

Rates of piscivory predict pharyngeal jaw morphology in a piscivorous lineage of cichlid fishes          下载免费PDF全文

Edward D. Burress  Alejandro Duarte  Wilson S. Serra  Marcelo Loureiro 《Ecology of Freshwater Fish》2016,25(4):590-598

The pharyngeal jaw apparatus is a key innovation hypothesised to increase foraging efficiency and facilitate utilisation of novel resources among teleost fishes. Here, we tested whether dietary characteristics could predict pharyngeal jaw morphology among eight species of Neotropical Crenicichla. Additionally, we tested the hypothesis that pharyngeal jaws may impose a functional constraint on piscivory via pharyngeal gape. We quantified the shape of the lower pharyngeal jaw (LPJ) using linear and geometric morphometrics and quantified diet using the relative volumetric proportions of prey items. We used principal component analysis to describe major axes of variation in LPJ shape and dietary patterns. The major axis of dietary variation significantly predicted LPJ morphology, which was driven by a significant relationship between LPJ shape and rates of piscivory. We also found that rates of piscivory predicted size‐corrected LPJ depth. Size‐corrected pharyngeal gape also significantly predicted rates of piscivory such that pharyngeal jaws may constrain piscivory by limiting pharyngeal gape. Strong form‐to‐function linkage between pharyngeal morphology and trophic patterns suggests an adaptive quality of the pharyngeal apparatus but may also impose functional constraints when consumers must switch prey or when prey availability is temporally or spatially unpredictable.  相似文献