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1.
Evidence for genetic distinction among sympatric ecotypes of Arctic char (Salvelinus alpinus) in south‐western Alaskan lakes
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Shannan L. May‐McNally Thomas P. Quinn Pamela J. Woods Eric B. Taylor 《Ecology of Freshwater Fish》2015,24(4):562-574
Resource polymorphism may play an important role in the process of speciation. The Arctic char (Salvelinus alpinus) exhibits great phenotypic and genetic diversity across its range, making it an ideal species for studies of resource polymorphism and divergence. Here, we investigated genetic variation at 11 microsatellite loci among 287 Arctic char from five isolated yet proximate postglacial lakes in south‐western Alaska that were previously examined for resource polymorphism. Significant differences in pairwise FST were detected among all lakes (range from 0.05 to 0.28, all P < 0.02). In one lake (Lower Tazimina Lake), we found evidence for two genetic groups of char and for significant differences in the distribution of microsatellite variability among at least two of the three previously described body size morphotypes (‘large’‐, ‘medium’‐, and ‘small’‐bodied char; maximum FST = 0.09; differences in admixture proportions). We also found a significant association between genetic admixture proportions and gill raker counts among body size morphs (r = ?0.73, P < 0.001). Our data represent the first record of genetically distinct sympatric morphs of Arctic char in Alaska and provide further evidence that differences in morphology associated with feeding (gill rakers) and growth trajectories reflect niche diversification and promote genetic divergence in Holarctic populations of Arctic char. 相似文献
2.
测定和分析了4种鱚属(Sillago)鱼类:斑鱚(Sillago aeolus)、亚洲鱚(S. asiatica)、多鳞鱚(S. sihama)和少鳞鱚(S. japonica)线粒体细胞色素b基因序列片段,比较了不同鱚属鱼类种间的序列差异,探讨了彼此间系统发育关系和分类地位。结果显示,4种鱼类平均核苷酸组成为T 29.9%、C 29.2%、A 21.5%、G 19.3%,种间平均净遗传距离在0.157到0.280之间。最大似然法构建的系统树显示,少鳞鱚和亚洲鱚首先聚类、再与多鳞鱚和斑鱚相聚,斑鱚是最晚分化出的鱼类。基于Cyt b基因序列核苷酸分歧速率计算得出4种鱼类发生遗传分化时间在距今785—1400年前的第三纪中新世(Miocene)。 相似文献
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4.
干热河谷泥石流流域不同分区土壤养分特征 总被引:1,自引:0,他引:1
以云南泥石流频发的小江流域为研究区域,根据该流域的微地貌特点,将流域划分为物源区、流通区、堆积区;为全面了解土壤肥力的分区异质性特征,结合各分区土地利用类型,分析其土壤物理结构、养分特征。结果表明:不同分区土壤颗粒组成差异性不大,土壤质地以粗粒和砾石为主,土壤沙石化明显,流通区土壤物理结构相对较好;小江流域山地土壤含水量总体受季节影响较大,而不同分区的土壤含水量则受垂直地带性因素影响,表现为流通区〉物源区〉堆积区;不同分区土壤养分含量受人类活动、土壤类型、土壤颗粒组成等因素影响,差异性特征复杂,总体含量丰富。 相似文献
5.
陈有君 《内蒙古农业大学学报(自然科学版)》2003,24(1):79-86
对运动电磁场的电场强度变量和磁感应强度变量做旋度及散度运算分析,表明除电位移变量项与经典Mexwell方程组的正负号不同外,大多数时变电磁场理论下的Maxwell方程都可以在一定条件下从运动电磁场的Maxweel方程组中导出。但在有些条件下运动电磁场的Maxwell创方程组仍然可以应用,并能得到正确的结果,而经典Maxwell方程组无法应用。这说明用“运动电场具有磁场特性;运动磁场具有电场特性”来描述电场与磁场之间的关系要比时变电磁场理论更符合自然规律。时变电磁场理论的Maxwell方程组是运动电磁场在特殊条件下的特殊形式。所谓时变电磁场可能是运动电磁场在特殊条件下的特殊表现,时变电场与时变磁场之间的相互转化可能是运动电磁场在特殊条件下所表现出的假象,并非电磁场的真正规律。时变电磁场理论的Maxwell方程组作为数学工具在一些领域中可以应用,但作为原理表达式,它们不是每个都正确的,也不是总对的。 相似文献
6.
Mayu Onodera Takayuki Nakajima Masami Nanzyo Tadashi Takahashi Donghe Xu Koki Homma 《Plant Production Science》2013,16(2):262-274
ABSTRACT Soil salinity is a major constraint to sustainable crop production. Genetic improvements are needed for growing soybean in salinity-prone environments. Salt-tolerant soybean genotypes alleviate a reduction in photosynthesis and growth under saline conditions; however, the detailed mechanisms involved remain unclear. Here, we aimed to clarify how Na and Cl root-to-leaf transport is quantitatively regulated, and to identify whether photosynthetic tolerance depends on traits associated with either stomata or with mesophyll tissues. Two pairs of pot-grown soybean near-isogenic lines (NILs) consisting of tolerant and susceptible counterparts, derived from a cross between salt-tolerant FT-Abyara and salt-sensitive C01, were subjected to salinity treatment in a rainout greenhouse. Comparison of photosynthetic responses between genotypes indicated that genotypic differences in salinity tolerance depended on the ability for sustained CO2 assimilation in mesophyll tissues, rather than stomatal conductance. The ratio of photosynthetic rate to intercellular CO2 concentration (A/Ci) declined exponentially with increasing Na and Cl concentration regardless of genotype, but tolerant genotypes effectively kept both elements at significantly low levels. Under saline conditions, tolerant genotypes reduced Na and Cl content at the two transport pathways: from root to stem, and from stem to leaf, but the reduction of Cl at each pathway was only minor. These results suggest that integrating genetic capacity for Cl transport regulation and osmotic adjustment should be an important target in salinity-tolerance soybean breeding. 相似文献
7.
用线粒体DNA的D-loop和Cytb基因序列分析方法研究了吉林延吉、敦化和辽宁法台3个区域的29尾拉氏鱼岁Phoxinus lagowskii Dybowsky的遗传多样性.经PCR扩增和测序,获得了783~785bp D-loop和818bpCyt b的同源序列.两者多态性遗传参数统计显示,29尾个体分别存在47(D-loop)和89(Cyt b)个变异位点,分别检测出15 (D-loop)和1l(Cyt b)个单倍型,总群体单倍型(Hd)分别为0.8966 (D-loop)和0.8990(Cyt b),核苷酸多样性指数(Px)分别为0.0246(D-loop)和0.0498 (Cyt b),平均核苷酸差异数(K)分别为19.2857(D-loop)和40.7365(Cytb).分子方差分析(AMOVA)结果表明,79.02%(D-loop)和81.69%(Cyt b)变异来自群体间,20.98%(D-loop)和18.31%(Cyt b)来自群体内.单倍型呈明显的地理差异,分成2个分支,一个以延吉群体为主,一个以法台群体为主.拉氏(鲮)的遗传多样性水平较高,群体间遗传分化明显.该结果可为拉氏(鲮)的种质资源保护提供参考. 相似文献
8.
回顾了近十五年来国内外对各科植物查尔酮合酶基因CHS分子进化的研究成果,并结合作者近年来对兰科植物CHS基因分子进化的研究结果,对兰科植物CHS基因分子进化和功能趋异的机制展开综述,揭示了植物中普遍存在的CHS基因分子进化以及伴随的功能趋异的现象和机制,初步探讨了CHS基因分子进化与生物进化和自然选择的关系。 相似文献
9.
付炜 《干旱区资源与环境》1998,12(3):105-112
本文介绍了地学空间数据迭代聚类的算法原理。根据类别分离度在线性映射变换下的不变性,用K-L变换进行地学空间数据的特征提取。在特征空间上两类分布的分离度只依赖于特征值最大和最小的两个特征向量,且其大小依赖于上述两个特征值与某个定值的偏差。据此可设计一个迭代过程,使分类后样本集的特征值都尽可能趋近某个定值,从而达到最佳分类结果。用该算法对乌鲁木齐河流域土壤类型进行了分类研究,取得了较好的效果。 相似文献
10.
We studied the effect of genotypes of planting stocks regarding the variation of the modulus of elasticity of tree trunks on standing trees (trunk-MOE), tree height (TH), and diameter at breast height (DBH) in a 19-year-old Japanese cedar plantation made with root cuttings. Trunk-MOE was assessed nondestructively using a tree-bending method. Genotypes of individual trees were detected using the random amplified polymorphic DNA (RAPD) technique. RAPD analysis revealed that the sampled plantation consisted of 14 genotypes. Genotypic effects on DBH and TH were unclear, and there was no significant difference among genotypes. This result indicated that an acquired variation should have more influence than an inherited variation on DBH and TH. For trunk-MOE, there were significant differences among the four largest genotypes at the 5% level. However the coefficient of variation in trunk-MOE of each genotype ranged from 7.5% to 26.8%. It seems reasonable to assume that the wide variation in trunk-MOE in a sampled plantation may depend on the environmental effect within a clone as well as on the genetic origin of clones. We therefore conclude that the use of multiple planting stocks from different cuttings for which the wood quality is unknown contributed strongly to the wide variation in trunk-MOE in the plantation of Japanese cedar. 相似文献