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We propose a simple model for analyzing the effects of microenvironmental variation in quantitative genetics. Our model assumes that the sensitivity of the phenotype to fluctuations in microenvironment has a genetic basis and allows for genetic correlation between trait value and microenvironmental sensitivity. We analyze the effects of short-term stabilizing and directional selection on the genotypic and microenvironmental components of phenotypic variance. Our model predicts that stabilizing selection on a quantitative trait increases developmental canalization. We show that stabilizing selection can result in an increase in the heritability. Our findings may provide an explanation for the results of selection experiments in which artificial stabilizing selection did not change the heritability coefficient or increased it.  相似文献   

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Inclusive fitness theory is central to our understanding of the evolution of social behavior. By showing the importance of genetic transmission through nondescendent relatives, it helps to explain the evolution of reproductively altruistic behaviors, such as those observed in the social insects. Inclusive fitness thinking is quantified by Hamilton's rule, but Hamilton's rule has often been criticized for being inexact or insufficiently general. Here I show how adopting a genic perspective yields a very general version that remains pleasingly simple and transparent.  相似文献   

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The equilibrium phenotypic variance of a normally distributed quantitative character P under soft selection is studied. This character is assumed to undergo Gaussian stabilizing selection W(p, x) = exp[–(px)2/2w2]. The environmentally determined optimum (x) is a normal variable with variance s2. A stable equilibrium with is found, so that increases both with increasing environmental heterogeneity and with increasing local intensity of stabilizing selection. It is shown that both genetic and environmental components of the variance are selected until this equilibrium is reached. Habitat selection, supposed to be normal (with variance H2) around the optimum, also increases the value. Nevertheless, relatively intense local stabilizing selection (w < s) and accurate habitat choice (H < s) are required for the initial spread and the evolutionary stability of this habitat selection.  相似文献   

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一类Holling功能性反应模型极限环的唯一性   总被引:2,自引:1,他引:2  
考虑功能性反应的捕食-食饵模型这里y表示捕食者种群的密度,当a-(22)≠0时它具有线性密度制约,x表示食饵种群密度,当φ(x)≡ax/(1+ωx)时称(1)为第二类功能性反应模型.文〔1〕研究了捕食者没有密度制约(对应于a_(22)=0)、食饵具有线性密度制约(对应于g(x)=b_1-a_(11)x)的Ⅱ类功能性反应模型(1),得到了极限环存在性及唯一性的完整结论.最近文〔2〕在a_(22)≠O的条件下讨论了系统(1),得到了极限环的存在性与不存在性等福建省自然科学基金和国家自然科学基金资助项目(19371069号).本文第一作者现为浙江大学访问学…  相似文献   

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利用19个优质杂交水稻品种(组合),采用双向逐步筛选,求出加工和外观品质性状与产量性状的最优相关子集,建立了品质性状的回归方程,并对子集作了广义相关分析。结果表明千粒重、穗长与糙米率、整精米率、垩白粒率的相关已反映了品质性状与产量性状相关的主要信息(90%以上),千粒重在21.96~27.64g、穗长在21.18~26.07cm范围内,增大千粒重可提高糙米率,但整米率下降、垩白粒率上升,适当缩短穗长可提高糙米率和整精米率,降低垩白粒率。  相似文献   

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重楼属花粉形态的研究   总被引:3,自引:1,他引:3  
本文对重楼属(paris L.)18个种和变种或变型的花粉形态进行了光学显微镜和电镜的观察和初步比较研究。就所观察过的种类看,花粉粒为扁球形,极面观椭圆形。左右对称。具一远极沟。外壁两层,外层厚于或等于内层。外壁纹饰有穴状、网状和皱-网状之分。不同的种类,其花粉大小和外壁纹饰均或多或少有所不同,其中有些种类的外壁纹饰比较特殊,可以作为区分种类甚至作为分组的依据或参考。  相似文献   

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