Pigmentation and mate choice in Drosophila

Many species of the fruitfly Drosophila are either sexually dimorphic for abdominal pigmentation (the posterior segments in males are black and those of females have thin dark stripes) or sexually monomorphic for this pigmentation (both sexes show striping). Kopp et al. report a correlation in two Drosophila clades between the expression of the bric-à-brac (bab) gene, which represses male-specific pigmentation in D. melanogaster females, and the presence of sexually dimorphic pigmentation. They suggest that sexual selection acted to produce sexual dichromatism in Drosophila by altering the regulation of bab, on the grounds that D. melanogaster males show a strong mate preference for females with lightly pigmented abdomens, and that this discrimination helps to maintain sexual dichromatism by preventing males from wasting time by courting other (darkly pigmented) males. Here we show that the mate discrimination observed by Kopp et al. may in fact have resulted from the nature of the strains and comparisons they used in their study and so could be irrelevant to mate choice in nature.     

Evolutionary genetics: evolution of mate choice in the wild

Qvarnstr?m et al. test whether the preference of female collared flycatchers (Ficedula albicollis) for males with large forehead patches could have evolved as a by-product of selection acting on male patch size. They find that the crucial genetic correlation between female choice and male patch size is not significant, and conclude that preference for large patches must have been shaped directly by selection. However, their use of the patch size of a female's social partner as a measure of choice is incomplete, and will result in low estimates of the potential for direct selection to shape female preference. Their study is therefore unable to resolve the question of how female preference for large forehead patches has evolved.     

Female transference and mate choice among Tana River red colobus.

Red colobus are one of a small number of primate species in which females have been reported to transfer between breeding groups more commonly than males. Several authors have hypothesised that in such species transference may serve to reduce the risk to females of producing offspring of lower fitness through inbreeding. The hypothesis offers no explanation of why females rather than males are responsible for outbreeding in these species, but remains plausible so long as male membership of breeding groups is relatively stable; for once members of one sex have evolved dispersal mechanisms reducing the risk of inbreeding, pressures on the other sex to do likewise will be lowered. Hence, if both sexes commonly migrate, the hypothesis is weakened. I describe here the membership dynamics of a group of Tana River red colobus, Colobus badius rufomitratus, which provide the first evidence of high rates of membership turnover by both sexes in primates, and speculate that the function of female transference in this case may be related to mate choice and the avoidance of infanticide.     

Testing the genetics underlying the co-evolution of mate choice and ornament in the wild

One of the most debated questions in evolutionary biology is whether female choice of males with exaggerated sexual displays can evolve as a correlated response to selection acting on genes coding for male attractiveness or high overall viability. To date, empirical studies have provided support for parts of this scenario, but evidence for all key genetic components in a natural population is lacking. Here we use animal-model quantitative genetic analysis on data from over 8,500 collared flycatchers (Ficedula albicollis) followed for 24 years to quantify all of the key genetic requirements of both fisherian and 'good-genes' models on sexual selection in the wild. We found significant additive genetic variances of all the main components: male ornament (forehead patch size), female mate choice for this ornament, male fitness and female fitness. However, when the necessary genetic correlations between these components were taken into account, the estimated strength of indirect sexual selection on female mate choice was negligible. Our results show that the combined effect of environmental influences on several components reduces the potential for indirect sexual selection in the wild. This study provides insight into the field of sexual selection by showing that genes coding for mate choice for an ornament probably evolve by their own pathways instead of 'hitchhiking' with genes coding for the ornament.     

等性杂化与不等性杂化

介绍了杂化轨道间夹角公式.通过计算讨论了等性杂化与不等性杂化,明确了区分等性杂化与不等性杂化的一般原则.     

Mutual mate choice in the Asiatic toad, Bufo gargarizans, exerts stabilizing selection on body size

Sexual selection is critical to both reproduction and evolution.The effects of male–male competition and female choice regarding body size have been examined in a large number of taxa,including toad species.Males and females have different optimal reproductive strategies,achieving breeding advantages in discrepant ways.Further,the relative contributions of intra-and inter-sexual size selection vary among species.Thus,to understand the mechanisms affecting mating success,it is important to consider both male–male and male–female interactions simultaneously and elucidate their interrelationship.In this study,we measured body sizes of all mated and unmated individuals in a population of Asiatic toad(Bufo gargarizans)and counted fertilized eggs of several clutches.Based on correlation and regression techniques,we tested for female choice and intra-sexual competition among males relative to body size gradients,and we compared the relative importance of these two processes for mating success.Our results reveal that male–male competition and female choice simultaneously contribute to sexual selection in toads.Furthermore,both interactions are most intense among smaller toads.The synergistic trends of male–male competition and female choice support the mutual mate choice hypothesis and works to stabilize body size in B.gargarizans.Normal distributions of breeding success relative to body size were detected for both sexes,suggesting that medium-sized individuals enjoy a reproductive advantage in the population studied.     

Adaptive plasticity in mate preference linked to differences in reproductive effort

There is abundant evidence for the existence of marked mate preferences in natural populations, but the occurrence of within-population variation in mate preferences has received little attention and is often regarded as nonadaptive deviation from the optimal norm. Here we show experimentally that the preference of female collared flycatchers Ficedula albicollis for male forehead patch size, a sexually selected trait, varies with the time of breeding, an environmental factor with strong effects on reproductive success. Contrary to expectations based on time-constrained choice models, only late-breeding females prefer males with a large patch size. The variation in mate preference matches a seasonal change in female reproductive success: long-term data reveal a positive relationship between female reproductive success and male patch size exclusively in late breeders. In addition, female reproductive effort, as assessed by clutch size, appears to be adjusted relative to both timing of breeding and male phenotype. We conclude that not only can mate preferences display adaptive plasticity within populations, but this plasticity can also be linked to differences in reproductive investment.     

涡虫整体原位杂交方法的优化改良

从原位杂交样品的预处理、固定液选择、杂交温度和时长选择、封闭时长等方面对日本三角涡虫整体原位杂交技术进行优化改良。实验表明,采用 NAC 处理 10 min、w=4%的多聚甲醛溶液固定、56oС 杂交 48 h 以及封闭 3 h 的改良方法可获得高特异性、低背景且着色清晰的实验结果。     

浅谈畜禽杂交的几种方式

介绍了畜禽的几种杂交方式,并分析了各自的优缺点,指出需注意的一些问题。     

荧光原位杂交技术及其在微生物生态学中的应用

介绍了荧光原位杂交技术的基本原理,讨论了该技术的操作程序及其在微生物生态学领域的应用。     

鹅掌楸属(Liriodendron)杂交育种回顾与展望

对我国鹅掌楸杂交育种工作进行了回顾与总结。自已故叶培忠教授开创该树种杂交育种工作以来40a的历程，概括地分为3个阶段：杂交可配性与杂种优势探索阶段，杂交后代试种及其生长适应性测定阶段，杂交育种工作全面发展阶段。关于杂交育种工作的主要进展则包括了解和掌握了鹅掌楸属种间杂交可配性、杂交胚胎学、杂交授粉生物学与杂交技术；揭示了杂交种生长优势的形成原因；选出一批优良杂交后代家系与无性系；总结出无性繁殖的技术；初步建立了推广示范点，探索了科研与开发的途径。最后对今后的工作进行了展望性的讨论。     

泥螺人工杂交育苗及中间培育技术

对2002年和2003年的6～7月先后4次从朝鲜某滩涂养殖场引进的规格为8.3～12.5 g泥螺1 299 kg,以及采集自江苏启东当地自然海区规格为3.3～2.7 g的优质泥螺675 kg,进行亲贝育肥蓄养、人工催产、杂交繁育、浮游幼虫培育、附苗和利用土池进行稚贝大规模苗种中间培育试验。2年间除受灾损失稚贝1.045亿粒外,共对5.555亿粒经中间培育的幼贝进行滩涂围网及池塘养殖。至2003年10月31日,共捕获规格为6.3～7.1 g的商品螺1 147 t,,产值931.7万元,经济社会效益显著,是适宜在江苏沿海滩涂作为产业化规模贝类增养殖的优良品种,此技术在国内尚未开展。     

基因组原位杂交中探针长度的优化

本文对普通野生稻Oryza rufipogon DNA的提取、纯化到最后将DNA剪切成300-500bp的整个过程进行了阐述．同时因为鲑鱼精DNA的G、C含量比较均匀，具有一定的剪切代表性，也对其进行了长度剪切，用来和普通野生稻Oryza rufipogon DNA进行比较，以得出其煮沸时间和剪切长度的关系是否具有普遍性，结果初步验证了普通野生稻Oryza rufipogon DNA的煮沸时间和长度变化的关系与鲑鱼精DNA的煮沸时间和长度变化的关系有很大差别，说明普通野生稻Oryza rutlpogon DNA的煮沸时间和长度变化的关系没有普遍性，而只能说明普通野生稻Oryza rufipogon DNA本身的特性。     

皱纹盘鲍与九孔鲍杂交的研究

采用皱纹盘鲍与九孔鲍进行杂交,并与两亲本自交进行育苗比较.结果表明:自交组的受精率、孵化率以及存活率显著高于杂交组(P0.05);皱纹盘鲍(♀)×九孔鲍(♂)和皱纹盘鲍(♂)×九孔鲍(♀)杂交的受精率分别为0.9%和3.2%,受精率存在显著差异(P0.05),而孵化率分别为12.4%和13.1%,二者差异不显著(P0.05),二者之间幼体存活率的差异也不显著(P0.05);自交组和杂交组之间的鲍生长速度存在明显的差异(P0.05),杂交组合的生长速度明显比自交组合的要快;但杂交组中稚鲍的存活率和自交组之间差异不显著(P0.05).     

西门塔尔牛与本地黄牛杂交试验效果分析

为了探索西门塔尔牛对凉山本地黄牛杂交改良效果,选择示范区测定了初生、6月龄和12月龄西本F1代的体重、体尺并与本地黄牛进行了比较,西本F1代牛的各项指标均比黄牛有明显的提高,并在全县29个乡得到了推广应用,经济效益显著。     

基于自适应分割和自适应量化的图像压缩算法

为弥补JPEG算法不能自适应不同属性图像的不足,提出一种基于自适应分割和自适应量化的图像压缩算法.利用多闲值分割将图像分割成不同尺寸的平滑子块和细节子块,不同子块采用不同DCT变换和量化方式.本文定义的压缩-信噪比增益(CPR)同时考虑了压缩比(CR)和峰值信噪比(PSNR),可有效评价图像压缩效果,实验结果表明,与传统JPEG算法相比,该算法在PSNR相同情况下,能够获得更高的CR;或者在CR相同情况下,能够获得更高的PSNR.     

烟草体细胞杂交再生植株的影响因素

利用体细胞杂交技术,可以克服传统的有性杂交遇到的诸多育种障碍,加速烟草品种选育进程.本文着重对影响烟草体细胞杂交成株的相关因素进行了论述,并讨论了体细胞杂交技术在烟草育种上的应用潜力.     

2003-2012年吉林省玉米审定品种杂交模式分析

对吉林省2003-2012年通过审定的中熟至晚熟熟期组配的272个普通玉米杂交种进行杂交模式分析,探讨在吉林省自然生态条件下不同杂交模式的应用效果,为今后玉米育种提供参考。结果表明:审定品种的亲本自交系来源以国内类群为主,以国外材料为辅。国内类群以Reid,旅大红骨,塘四平头为主,以Lancaster和PN类群为辅。Reid和塘四平头类群总体呈现上升趋势,旅大红骨、PN和Lancaster类群呈现下降趋势。Reid×旅大红骨、PN×旅大红骨和L×T呈现下降趋势,Reid×塘四平头和外杂选×其它类群呈现上升趋势。