黄土高原六道沟流域8种植物根际细菌与AMF群落多样性研究

采用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)方法,研究了神木县六道沟流域8种植物根际细菌与丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落多样性及其相互关系.目的是获得有关植物根际细菌和AMF群落的多样性指数,为生态环境修复提供科学依据.结果表明,8种植物根际细菌和AMF的种类和数量有较大差异,其中刺槐根际细菌的Shannon指数最高(4.01),垂柳最低(2.18),根际AMF的Shannon指数最高为小叶杨(2.07),最低为沙棘(1.21);聚类分析(cluster analysis)和冗余分析(redundancy analysis)结果表明,不同植物根际细菌和AMF的群落结构有较大差异,但同时部分植物间也存在相似性;8种植物根际细菌和AMF的多样性指数总体呈极显著的正相关(P<0.01);冗余分析结果表明在根际土壤环境因子中,对根际微生物群落多样性影响最大的环境因子为有机质含量.植物种类和根际环境对根际微生物群落结构有较大影响,同时,刺槐的根际细菌和AMF群落多样性指数均较高,故可作为六道沟流域植被恢复的先锋树种.     

Population frequencies of alternative male phenotypes in tree lizards: geographic variation and common-garden rearing studies

Tree lizards (Urosaurus ornatus) vary in throat fan (dewlap) color. Earlier, we described five dewlap types (Orange, Orange-Blue, Yellow, Yellow-Blue, and Blue), and reported that only males had blue in the dewlap and that presence or absence of a discrete blue patch was correlated with male alternative reproductive phenotypes in a central Arizona population. Here, with a modified scheme characterizing two dewlap elements, background color (orange, yellow, blue) and blue patch occurrence, we assessed: (1) sexual, annual, and geographic variation in the frequencies of dewlap elements; (2) simple habitat correlates; and (3) the effects of laboratory rearing regime on dewlap type. Within a population, frequencies of males and females expressing orange or yellow backgrounds did not differ, suggesting that control of background is similar in the sexes. Within several populations, frequencies of the dewlap elements did not differ across years (and probably generations), indicating that phenotype frequencies are relatively stable. Among five populations frequencies of background colors varied, as did frequencies of male types (blue patch present or absent). Dewlap frequencies did not correlate with habitat (boulders or mesquite trees), although few populations were sampled. In male and female offspring reared from eggs to sexual maturity in a common-garden laboratory study, background color frequencies in both sexes and blue patch frequencies in males differed among offspring from different populations. Offspring frequencies matched respective parental population frequencies. Results suggest that among-population variation in frequencies of the two dewlap elements are mediated by differences in genetics, in maternal effects, or both. Thus, differences in male behavior functionally linked to the blue patch also may be controlled by genetic or maternal effects. Received: 17 January 1997 / Accepted after revision: 30 August 1997     

Queen dimorphism and reproductive strategies in the fire ant Solenopsis geminata (Hymenoptera: Formicidae)

Alate trapping studies of a monogyne population of the fire ant Solenopsis geminata indicate that two sizes of gynes are produced. Macrogynes, which participate in late spring and summer mating flights, are larger, fattier, and more than twice as heavy as microgynes, which participate in fall mating flights. Three patterns of gyne production were observed in 51 colonies studied: 35 produced macrogynes only, 9 produced microgynes only, and 7 produced both morphs, contributing to both summer and fall mating flights. Behavioral evidence and rearing studies suggest that macrogynes found new colonies independently, whereas microgynes achieve colony queen status by infiltrating or being adopted by established colonies. Of the total number of female alates collected from the trapped colonies, 56% were microgynes. However, because of their smaller size and lower fat content, microgynes made up only one-third of the caloric investment in female alates. By measuring the thorax lengths of queens from mature colonies, we determined that at least 56% were macrogynes and 35% or more were microgynes. These results indicate that as a reproductive strategy, colony investment in microgyne production may have at least as high a payoff as investment in macrogyne production.This is publication #24 of the Fire Ant Research Team     

Surviving the change to warning colouration: density-dependent polyphenism suggests a route for the evolution of aposematism

Summary. How warning colouration first appeared remains a disputed question in evolutionary biology. A density-dependent transition from crypsis to aposematism that occurs during phase change in the desert locust (Schistocerca gregaria) provides insight into the conditions under which acquiring warning colouration is adaptive. When crowded for only a few hours, solitarious locusts cease avoiding each other and actively aggregate. This occurs well before they acquire warning colouration. We show that accompanying this early behavioural gregarisation is a remarkable shift in feeding behaviour, in which solitarious insects switch from being deterred by a toxic plant alkaloid to feeding avidly upon foods containing it. A computer simulation shows how crypsis ceases to be effective as an anti-predator strategy when solitarious locusts are crowded, how chemical defence becomes essential as conspicuousness increases with local density, and how warning colouration becomes advantageous under these conditions. These findings provide empirical evidence for an adaptive route for the change from a cryptic edible phenotype to a brightly coloured toxic one.     

Site Tenacity in the Willow Ptarmigan (<Emphasis Type="Italic">Lagopus lagopus</Emphasis> L.) in the Northern Yamal Peninsula

The return of willow ptarmigans to the sites in which they nested the previous year has been studied using color banding. No factors influencing the return index have been revealed, except for its dependence in males on the time when spring begins in a given year. In northernYamal, in contrast to the temperate zone, some surviving birds fail to return to their former nesting sites. Polymorphism of individuals with respect to territorial behavioral strategy is proposed for L. lagopus populations at the northern boundary of the species range.__________Translated from Ekologiya, No. 3, 2005, pp. 215–221.Original Russian Text Copyright © 2005 by Tarasov.     

城市污水处理厂活性污泥中氨氧化菌群落结构研究

为了解析污水处理厂中氨氧化菌(AOB)的群落结构,以及处理工艺、规模等参数对AOB群落结构的影响,采用针对AOB功能基因氨单加氧酶(amoA)的末端限制性片段长度多态性技术(T-RFLP)、克隆测序等方法,研究了北京市6个污水处理厂的9个污水处理系统中AOB的群落结构.T-RFLP指纹图谱表明不同污水处理系统中AOB的群落结构有所不同,主要的末端限制性片段(T-RF)为354、491和291 bp.T-RFLP指纹图谱及聚类分析表明,污水处理工艺对系统中AOB的群落结构影响较小,而处理规模对AOB的群落结构有一定的影响.对功能基因amoA的系统发育分析表明,污水处理系统中优势AOB均为Nitrosomonasspp.,而非Nitrosospiraspp..这可能是Nitrosomonasspp.的最大比增长速率(μmax)较高,使其更容易成为活性污泥系统中的优势AOB.     

The dissolution of cooperative groups: mechanisms of queen mortality in incipient fire ant colonies

In several species of ants, queens often form temporary cooperative associations during colony foundation. These associations end soon after the eclosion of the first workers with the death or expulsion of all but one of the queens. This study examined competition between foundress queens of the fire ant Solenopsis invicta. Although attacks by the workers contributed to queen mortality, queens gained no advantage by producing more workers than their co-foundresses. Restriction fragment length polymorphism analysis of mitochondrial DNA showed that the queen producing more workers during colony founding was no more likely to survive than the less productive queen. In experimentally manipulated colonies in which all the workers were daughters of only one of the queens, the mother of the workers was no more likely to survive than the unrelated queen. Queens producing diploid males reared fewer offspring but were as likely to survive as queens producing only workers. These results suggest that workers do not discriminate between related and unrelated queens within colonies. Aggressive encounters between queens were common. Queens were more likely to die or be expelled if paired with heavier queens or if they lost more weight than their co-foundress during the claustral period. Finally, when queens were separated by screens through which workers could pass, the workers usually attacked and killed the queen farther from the brood. These results suggest that queen survival is promoted by a high fighting ability relative to co-foundresses, rather than by increased worker production, and that workers respond to queen differences that are independent of kinship. Received: 8 September 1995/Accepted after revision: 5 March 1996     

Effect of TRF1 rs3863242 polymorphism on telomere length in omethoate-exposed workers

Abstract

Telomere length was found to be associated with omethoate exposure and polymorphisms in certain genes among occupational workers. However, whether the polymorphisms in telomere-binding protein genes influence telomere length remains unclear. To explore the correlation between telomere length and polymorphisms in telomere-binding protein genes, telomere length in peripheral blood leukocytes was determined by real-time quantitative polymerase chain reaction in 180 omethoate-exposed workers and 115 healthy controls. Polymorphisms in 10 pairs of alleles were detected using flight mass spectrometry or polymerase chain reaction–restriction fragment length polymorphism technique. The results showed that individuals with GG genotype in TRF1 rs3863242 had longer telomere lengths than those with AG?+?AA genotype in the control group (p?=?0.005). The multiple regression analysis suggested that both omethoate exposure (b?=?0.526, p?<?0.001) and TRF1 rs3863242 GG (b?=?0.220, p?=?0.002) were related to a longer telomere length. In conclusion, GG genotype in TRF1 rs3863242 is linked to prolongation of telomere length, and individuals with GG genotype are recommended to strengthen health protection in a Chinese occupational omethoate-exposed population.     

Morphological-anatomical features of underground organs in some higher plant species in relation to their adaptation to ecological conditions

In seven higher plant species of different taxa, structural features of underground organs have been considered, and the levels of intraspecific variation in some characters of these organs have been determined. Different pathways of the structural adaptation of these species to the environment are demonstrated on the morphological and anatomical levels.Translated from Ekologiya, No. 2, 2005, pp. 97–105.Original Russian Text Copyright © 2005 by Tarshis.