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.     

Plant genetics: increased outcrossing in hothead mutants

Arising from: S. J. Lolle, J. L. Victor, J. M. Young & R. E. Pruitt 434, 505-509 (2005); Lolle et al. reply. Lolle et al. report that loss-of-function alleles of the HOTHEAD (HTH) gene in Arabidopsis thaliana are genetically unstable, giving rise to wild-type revertants. On the basis of the reversion of many other genetic markers in hth plants, they suggested a model in which a cache of extragenomic information could cause genes to revert to the genotype of previous generations. In our attempts to reproduce this phenomenon, we discovered that hth mutants show a marked tendency to outcross (unlike wild-type A. thaliana, which is almost exclusively self-fertilizing). Moreover, when hth plants are grown in isolation, their genetic inheritance is completely stable. These results may provide an alternative explanation for the genome wide non-mendelian inheritance reported by Lolle et al.     

Plant genetics: hothead healer and extragenomic information

Lolle et al. suggest that non-mendelian inheritance in Arabidopsis thaliana might be attributable to an ancestral RNA-sequence cache, whereby the RNA genome of previous generations causes a high rate of reversion of the plant's mutant hothead (hth) and erecta (er) genes. Here I describe a 'distributed genome' model that also explains their results, in which mutant hth DNA is restored by homologous sequences present in the genome itself. This model has implications for the generation of diversity without mating.     

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.     

Plant genetics: gene transfer from parasitic to host plants

Plant mitochondrial genes are transmitted horizontally across mating barriers with surprising frequency, but the mechanism of transfer is unclear. Here we describe two new cases of horizontal gene transfer, from parasitic flowering plants to their host flowering plants, and present phylogenetic and biogeographic evidence that this occurred as a result of direct physical contact between the two. Our findings complement the discovery that genes can be transferred in the opposite direction, from host to parasite plant.     

姜科植物古汉名考证

在我国古代典藉中记载有许多姜科植物，其名称与现代名称大多都不一致．为了沟通古今、沟通中外、弘扬我国古文化，笔者收集并考证了姜科植物古汉名４２个，归属于姜科的山姜属、砂仁属、姜黄属、姜花属、山奈属、姜属，共１８种．     

江西白鹭洲书院植物配置研究

通过实地调查分析,对我国古代著名书院之一———江西白鹭洲书院的植物配置进行了详细分析,探讨了其植物种类与配置特点。     

冕宁县荞麦属植物环境特征分布分析

通过对凉山州冕宁县32个乡镇的野生荞麦属植物及种质资源进行考察,发现并收集到分布于冕宁县不同生态环境下的荞麦属植物标本种类8个种、1个变种共计23个,种子资源46份.同时,初步明确了冕宁县荞麦属植物种类的特征和地理分布.     

荆州古城封闭型廊道景观的植物多样性研究

以植物为主,加上荆州古城墙、动物、水体等构成的封闭型廊道景观具有显著的生态效应.测定了荆州古城墙植被中乔木的Simpson多样性指数值和Shannon-wiener多样性指数值,测定了草本与藤本等植物的重要值及其他相关数据,并得出B样方的植物多样性数值最高(西南角)、I点的植物多样性数值最低等结论,筛选出枫杨、井栏边草、土牛膝、紫堇、薏苡等乡土植物.