Selection analysis on the rapid evolution of a secondary sexual trait

Evolutionary analyses of population translocations (experimental or accidental) have been important in demonstrating speed of evolution because they subject organisms to abrupt environmental changes that create an episode of selection. However, the strength of selection in such studies is rarely measured, limiting our understanding of the evolutionary process. This contrasts with long-term, mark–recapture studies of unmanipulated populations that measure selection directly, yet rarely reveal evolutionary change. Here, we present a study of experimental evolution of male colour in Trinidadian guppies where we tracked both evolutionary change and individual-based measures of selection. Guppies were translocated from a predator-rich to a low-predation environment within the same stream system. We used a combination of common garden experiments and monthly sampling of individuals to measure the phenotypic and genetic divergence of male coloration between ancestral and derived fish. Results show rapid evolutionary increases in orange coloration in both populations (1 year or three generations), replicating the results of previous studies. Unlike previous studies, we linked this evolution to an individual-based analysis of selection. By quantifying individual reproductive success and survival, we show, for the first time, that males with more orange and black pigment have higher reproductive success, but males with more black pigment also have higher risk of mortality. The net effect of selection is thus an advantage of orange but not black coloration, as reflected in the evolutionary response. This highlights the importance of considering all components of fitness when understanding the evolution of sexually selected traits in the wild.     

Preadapted for invasiveness: do species traits or their plastic response to shading differ between invasive and non‐invasive plant species in their native range?

Aim Species capable of vigorous growth under a wide range of environmental conditions should have a higher chance of becoming invasive after introduction into new regions. High performance across environments can be achieved either by constitutively expressed traits that allow for high resource uptake under different environmental conditions or by adaptive plasticity of traits. Here we test whether invasive and non‐invasive species differ in presumably adaptive plasticity. Location Europe (for native species); the rest of the world and North America in particular (for alien species). Methods We selected 14 congeneric pairs of European herbaceous species that have all been introduced elsewhere. One species of each pair is highly invasive elsewhere in the world, particularly so in North America, whereas the other species has not become invasive or has spread only to a limited degree. We grew native plant material of the 28 species under shaded and non‐shaded conditions in a common garden experiment, and measured biomass production and morphological traits that are frequently related to shade tolerance and avoidance. Results Invasive species had higher shoot–root ratios, tended to have longer leaf‐blades, and produced more biomass than congeneric non‐invasive species both under shaded and non‐shaded conditions. Plants responded to shading by increasing shoot–root ratios and specific leaf area. Surprisingly, these shade‐induced responses, which are widely considered to be adaptive, did not differ between invasive and non‐invasive species. Main conclusions We conclude that high biomass production across different light environments pre‐adapts species to become invasive, and that this is not mediated by plasticities of the morphological traits that we measured.     

Survey of termite-inhabited soil and mosquito breeding sites in Lucknow,India for potential mycopathogens of Anopheles stephensi

A mycological survey was carried out on the fruit surface of Indian jujube during its growth period (before harvest). A total of 32 microfungi belonging to 20 genera were isolated by surface washing technique. Artificial inoculations with the isolated myco-propagules were also performed in mature jujube fruits and most of them were able to cause rot of varying severity. However, Monodictys castaneae, Eupenicillium lapidosum, Paecilomyces fumosoroseus, Trichurus spiralis and Acremonium spp., although present on the fruit surface, were not able to cause rot, indicating lack of specific macerating enzymes necessary for postharvest pathogenesis. This revised version was published online in June 2006 with corrections to the Cover Date.     

论植物园的活植物收集

对植物园活植物收集评价、引种中的取样方法和迁地保护种群大小等问题进行了论述.对活植物收集的评价包括科学性和代表性,最具有科学意义的是经过调查从野外收集的有完整记录的材料,其次是从植物园等机构 引种的有记录的材料,再次是从各地引种的基本上无记录的材料.根据收集物的代表性可分为具有保护意义的收集和保护性收集.取样技术主要针对保护性收集而言,要求收集样本能涵盖该物种95%以上、频率大于5%的等位基因.活植物收集种群的大小应从科学性和现实性二方面来考虑,对植物园里大量的具有保护意义的收集,其种群大小为乔木10～20株,灌木40～50株,草本100～200株;对于保护性收集则至少为乔木50～100株,灌木200株或更多,草本300～500株以上.另外,对当前植物园活植物收集圃建设的一些重要问题也进行了探讨.     

几种花卉植物对污泥中铅的富集特征

土地利用是资源化利用城市污水厂污泥的有效途径。为了解污泥中重金属污染物在土壤、植物之间的迁移富集规律,选用8种园林用植物进行污泥混配土种植实验。结果表明,植物对污泥混配土土壤中铅的富集能力,以及铅在植物中各器官的富集系数均不同,且不同种类植物差别较大。植物根部对铅有较强的富集能力,其次是叶和茎。菊花对铅的富集能力较强。植物对土壤中铅的富集能力也受土壤铅含量和赋存形态影响。     

Short distances between extreme microhabitats do not result in ecotypes in Syntrichia caninervis

Abstract

Phenotypic variation occurs in many populations of plants. When this variation occurs along an environmental gradient, the immediate question is whether the variation is attributed to phenotypic plasticity, ecotypes, or some combination of the two. The moss Syntrichia caninervis appears morphologically variable along an environmental gradient changing rapidly from low light, low temperature, and high moisture levels in the understory microhabitat to high light, high temperature, and low moisture levels in the intershrub microhabitat. We tested for the presence of physiological variation using recovery from a heat-shock event in a mimicked microhabitat light environment, and for morphological variation using a common garden with the ultimate goal of attributing observed variation to plasticity, genetic variation, or a combination. The results suggest that plasticity plays a large role in trait variation. Photosynthetic recovery depended on the current light levels of an environment and not the original microhabitat. The supposed morphological variation in the field was not reflected in the test traits (awn length, leaf area, and shoot volume) and further growth in a common garden continued to show no variation between microhabitats.     

Young,intact and nested retrotransposons are abundant in the onion and asparagus genomes

Background and Aims

Although monocotyledonous plants comprise one of the two major groups of angiosperms and include >65 000 species, comprehensive genome analysis has been focused mainly on the Poaceae (grass) family. Due to this bias, most of the conclusions that have been drawn for monocot genome evolution are based on grasses. It is not known whether these conclusions apply to many other monocots.

Methods

To extend our understanding of genome evolution in the monocots, Asparagales genomic sequence data were acquired and the structural properties of asparagus and onion genomes were analysed. Specifically, several available onion and asparagus bacterial artificial chromosomes (BACs) with contig sizes >35 kb were annotated and analysed, with a particular focus on the characterization of long terminal repeat (LTR) retrotransposons.

Key Results

The results reveal that LTR retrotransposons are the major components of the onion and garden asparagus genomes. These elements are mostly intact (i.e. with two LTRs), have mainly inserted within the past 6 million years and are piled up into nested structures. Analysis of shotgun genomic sequence data and the observation of two copies for some transposable elements (TEs) in annotated BACs indicates that some families have become particularly abundant, as high as 4–5 % (asparagus) or 3–4 % (onion) of the genome for the most abundant families, as also seen in large grass genomes such as wheat and maize.

Conclusions

Although previous annotations of contiguous genomic sequences have suggested that LTR retrotransposons were highly fragmented in these two Asparagales genomes, the results presented here show that this was largely due to the methodology used. In contrast, this current work indicates an ensemble of genomic features similar to those observed in the Poaceae.     

南方红壤区3年生茶园土壤呼吸特征

为探讨南方红壤区茶园的土壤呼吸特征,采用LI-Cor8100开路式土壤碳通量测定系统观测3年生茶园系统的土壤呼吸速率,对茶园土壤呼吸速率的季节变化和在茶行尺度上的空间异质性进行了研究。结果表明,茶园土壤呼吸速率的月动态变化呈明显的单峰曲线特征,峰值出现在8月;茶园土壤呼吸速率的月动态变化与温度呈极显著相关(P<0.01),土壤10 cm的温度能够解释茶园不同观测区域土壤呼吸速率月动态变化的67.79%~88.52%;用指数方程计算的茶园不同观测区域土壤呼吸Q10值为1.58~1.86。在茶行尺度上,茶园土壤呼吸速率存在明显的空间异质性,土壤呼吸速率通常在距离茶树基部较近的位置较高;根系生物量能够解释茶园土壤呼吸速率在茶行尺度上空间变异的82.68%。因此,根系分布的空间差异是造成茶园土壤呼吸速率空间异质性的主要原因。     

Microbial composition affects the functioning of estuarine sediments

Although microorganisms largely drive many ecosystem processes, the relationship between microbial composition and their functioning remains unclear. To tease apart the effects of composition and the environment directly, microbial composition must be manipulated and maintained, ideally in a natural ecosystem. In this study, we aimed to test whether variability in microbial composition affects functional processes in a field setting, by reciprocally transplanting riverbed sediments between low- and high-salinity locations along the Nonesuch River (Maine, USA). We placed the sediments into microbial ‘cages'' to prevent the migration of microorganisms, while allowing the sediments to experience the abiotic conditions of the surroundings. We performed two experiments, short- (1 week) and long-term (7 weeks) reciprocal transplants, after which we assayed a variety of functional processes in the cages. In both experiments, we examined the composition of bacteria generally (targeting the 16S rDNA gene) and sulfate-reducing bacteria (SRB) specifically (targeting the dsrAB gene) using terminal restriction fragment length polymorphism (T-RFLP). In the short-term experiment, sediment processes (CO₂ production, CH₄ flux, nitrification and enzyme activities) depended on both the sediment''s origin (reflecting differences in microbial composition between salt and freshwater sediments) and the surrounding environment. In the long-term experiment, general bacterial composition (but not SRB composition) shifted in response to their new environment, and this composition was significantly correlated with sediment functioning. Further, sediment origin had a diminished effect, relative to the short-term experiment, on sediment processes. Overall, this study provides direct evidence that microbial composition directly affects functional processes in these sediments.     

The garden of the “Casa delle Nozze di Ercole ed Ebe“ in Pompeii (Italy): Palynological investigations

ABSTRACT

Palynological investigations in the garden of the “Casa delle Nozze di Ercole ed Ebe“ in Pompeii revealed the presence of Vitis and Citrus. Citrus has often been said to be cultivated in Roman times, but no plant remains have ever confirmed this hypothesis as regards Pompeii. In this paper, we give evidence for an early cultivation of this plant in a garden. Analyses revealed that, as already observed in other gardens, the ground was covered by herbs which were the same as those found in ancient and contemporary meadows of the Vesuvian area.