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排序方式: 共有230条查询结果,搜索用时 15 毫秒
201.
Quantitative genetics of zooplankton life histories 总被引:1,自引:0,他引:1
K. Spitze 《Cellular and molecular life sciences : CMLS》1995,51(5):454-464
Quantitative genetic techniques are powerful tools for use in understanding the microevolutionary process. Because of their size, lifespan, and ease of culture, many zooplankton species are ideal for quantitative genetic approaches. As model systems, studies of zooplankton life histories are becoming increasingly used for examination of the central paradigms of evolutionary theory. Two of the fundamental empirical questions that zooplankton quantitative genetics studies can answer are: 1) How much genetic variance exists in natural populations for life history traits? 2) What is the empirical evidence for trade-offs that permeate life history theory based on optimality approaches? A review of existing data onDaphnia indicates substantial genetic variance for body size, clutch size, and age at first reproduction. Average broad-sense heritabilities for these three characters across 19 populations of 6 species are 0.31, 0.31, and 0.34, respectively. Although there is some discrepancy between the two pertinent studies that were designed to decompose the total genetic variance into its additive and non-additive components, a crude average seems to suggest that approximately 60% of the total genetic variance has an additive basis. The existing data are somewhat inconsistent with respect to presence/absence of trade-offs (negative genetic correlations) among life history traits. A composite of the existing data seems to argue against the existence of strong trade-offs between offspring size and offspring number, between present and future reproduction, and between developmental rate and fecundity. However, there is some evidence for a shift toward more negative (less positive) covariances in more stressful environments (e.g., low food). Zooplankton will prove to be very useful in future study in several important areas of research, including the genetics and physiology of aging, the importance of genotype-environment interaction for life history traits, and the evolution of phenotypic plasticity. 相似文献
202.
动物育种中AFLP分子标记技术的应用 总被引:2,自引:0,他引:2
江昱 《西南民族学院学报(自然科学版)》2004,30(2):205-209
简述了AFLP分子标记的原理、流程、技术关键及其优化措施.对AFLP技术的特点进行了评价.综述其在动物育种中的研究.最后对AFLP的应用前景进行展望. 相似文献
203.
204.
论中医遗传学新学特点及实验初阶 总被引:2,自引:0,他引:2
本文对将兴起的中医遗传学关于中药药理遗传实验,自然整体性状遗传观察,行为遗传“象”的宏观表征以及弥补中国遗传学史空白等特色的研究领域进行了论述。 相似文献
205.
本文将遗传算法用于TSP问题的求解,并结合爬山搜索法的思想提出了一个新的遗传算子,实验表明效果明显。 相似文献
206.
Freshwater gastropods (Basommatophora and Prosobranchia) harbor a variety of mating systems. In particular, apomictic parthenogenesis in prosobranchs and self-fertilization in the hermaphrodite pulmonates may be viable alternatives to outcrossing sexuality in a number of species. The coexistence of different mating systems in extant populations provides opportunities to examine the forces directing their evolution. We review the models analyzing and predicting genetic variability in subdivided populations, with an emphasis on the effects of inbreeding. Population genetic data on freshwater pulmonates are examined in the context of selfing rates and the loss of variability under selfing. Furthermore, the genetic and demographic factors thought to influence mating system evolution are considered, and we highlight the different approaches available to estimate mating system parameters, in particular the selfing rate. Recent population biological studies on polyploid species (Bulinus truncatus, Ancylus fluviatilis) indicate that selfing is the predominant mating system. These studies have contributed to a deeper understanding of conceptual issues in the evolution of selfing rates. Throughout, we emphasize the need for further carefully designed studies. 相似文献
207.
采用随机数学的方法对遗传学中广泛应用的Hardy-Weinberg遗传平稳性定理给出精确的数学证明 相似文献
208.
文章首先指出马克思技术研究方法从还原法到历史发生学方法的变革,接着分析了马克思技术思想变化的标志“技术”内涵的历史性变化;梳理并阐述了马克思技术思想的几对矛盾:文本解读与哲学(前后期哲学)推演的技术思想的矛盾;预成的与生成的技术思想的矛盾;前后期哲学思想推演的技术矛盾,并指出,在历史发生学看来,所谓矛盾实质是马克思技术思想生成、发展、成熟的见证。 相似文献
209.
林木RAPD标记技术研究进展 总被引:6,自引:0,他引:6
综述了RAPD该标记在国内外林木遗传图谱构建、群体遗传多样性分析、系统进化研究、品种分类鉴定、DNA指纹分析和性状遗传品质改良等方面的研究进展和发展趋势, 指出随着理论和实验技术研究的不断深入, 分子标记技术将使林业生产迈上新的台阶. 相似文献
210.
人是谁创造的 1909年9月15日(农历八月初二),谈家桢出生于浙江慈溪一邮务员家庭.从小随父亲工作的频繁调动而飘泊四方:台州、海门、舟山、南浔、杭州、百官、绍兴、龙泉和慈溪等地.尽管谈家桢的父亲文化程度不高,毕竟见多识广,深感子女教育对家庭及他们日后前程的重要性.谈家桢5岁那年,父亲调到舟山邮局,工作相对稳定后,便腾出精力教子女识字. 相似文献