内蒙古山杏种群表型变异

为明确内蒙古山杏(Armeniaca sibirica)种群间和种群内的表型变异程度和变异规律, 以内蒙古山杏自然分布区的13个种群的23个表型性状为研究对象, 采用巢式方差分析、多重比较、变异分析、相关性分析和主成分分析等多种分析方法, 对种群间和种群内的表型多样性及其与地理生态因子的相关性进行了讨论。研究结果表明: 内蒙古山杏的表型性状在种群间和种群内均存在丰富的变异, 种群间的变异大于种群内的变异, 表型性状的平均分化系数为73.03%, 种群间变异是山杏表型变异的主要变异来源。各性状的平均变异系数为14.28%, 变异幅度为7.01%-27.23%, 其中核的变异系数最大, 果的变异系数最小。土默特左旗万家沟种群表型多样性最丰富, 科尔沁右翼前旗察尔森种群表型多样性最小。表型性状主要受经度、年降水量以及年日照时间3个主要地理生态因子影响。通过主成分分析可以把13个种源区划为四大类, 其中乌拉山种群的叶性状和阿鲁科尔沁旗种群的核性状受地理生态因子影响最大。     

High-level phenotypic variations in populations of Armeniaca sibirica in Nei Mongol,China

Aims Our objectives were to determine the variations in phenotypic traits of Armeniaca sibirica populations and their spatial patterns. Methods We used nested variation, coefficient of variation, multi-comparison, correlation analysis and principal component analysis to analyze the 23 phenotypic traits for 130 individuals in 13 populations of A. sibirica. Important findings The results showed that there were significant differences in phenotypic variations among and within populations. The variation was greater among populations (47.15%) than within population (16.43%). The mean phenotypic differentiation coefficient was 73.03% among populations, indicating the variance among populations being the main source of the phenotypic variation. The average variation coefficient of 23 traits ranged from 7.01% to 27.23%, with an average of 14.28%. The variation coefficient of nutlet was highest (15.67%), and the variation coefficient of fruit was smallest (12.11%). The phenotypic diversity is highest in Wanjiagou Tumotezuoqi and smallest in Horqin, Right Front Banner Chaersen. Longitude, mean annual precipitation and sunshine duration were significantly correlated with major traits of phenotypic. The 13 populations could be divided into four groups according to the principal component analysis. Leaf traits of Wula Mountain and nutlet traits of Archorchin Banner were significantly correlated with ecological and geographic factors.     

克隆和有性亲体效应及其调控机制

植物表型受自身基因型、所处环境及其亲体所经历环境的共同影响;其中,亲体环境对子代表型的影响被称为亲体效应。亲体效应不仅可通过有性繁殖产生的种子传递给后代(即有性亲体效应),也可以通过克隆生长等无性繁殖产生的分株传递给后代(即克隆亲体效应)。亲体效应对植物种群,特别是对有性繁殖受限、缺乏遗传变异的克隆植物种群的长期进化可能发挥着极其重要的作用,因此,对亲体效应研究进展的梳理非常必要。对克隆亲体效应和有性亲体效应的内涵进行了阐释,并论述了克隆和有性亲体效应对子代表型、适合度、种内/种间竞争能力以及种群/群落结构和功能的潜在影响;阐述了亲体效应的潜在调控机制,包括供给机制、代谢物质调控机制、表观遗传机制等;论述了克隆亲体效应在克隆植物适应进化中的作用。未来可以就克隆亲体效应的遗传稳定性及其对克隆生活史性状变异的贡献程度,以及克隆和有性亲体效应引起的表型多样性对种内/种间关系、种群/群落多样性及生态系统结构、功能和稳定性的影响开展深入研究。     

Phenotypic variation and promiscuity in a wild population of pure dingoes (Canis dingo)

Phenotypic diversity occurs in natural populations as a result of the interaction between an individual's genotype and the environment. Nevertheless, individual variation in phenotypic traits such as coat colour and body size is routinely used to differentiate between “pure” dingoes Canis dingo and dingo‐dog hybrids. Extensive anthropogenic impacts and widespread hybridization with domestic dogs has hindered our ability to study intact dingo populations and, therefore, most of our basic understanding of dingo biology (e.g., phenotypic variation, mating systems, genetic diversity) stems from observational studies on perturbed populations. We sampled a relatively undisturbed population of dingoes, from arid Australia, to determine their purity and genetic diversity. We explored their mating strategy using a pedigree built from genetic data and examined how phenotypic variation was influenced by age, sex, heterozygosity, and relatedness. Coat colour was our measure of phenotype and our population displayed four types (sandy, black & tan, white, and sable). All dingoes (n = 83) possessed a high level of dingo ancestry (mean purity > 90%) and were closely related to each other; with all but one individual related as full‐sibling or parent–offspring. Our pedigree shows both monogamous and promiscuous mating strategies exist within an undisturbed population. Variation in coat colour or body size cannot be used to infer a dingo's level of purity because the phenotype of pure dingoes is intrinsically variable. The breeding system of dingoes was long thought to be monogamous, but we provide genetic evidence for numerous mating strategies including both long‐term monogamy and extreme promiscuity.     

Phenotypic and allozyme variation in Mediterranean and desert populations of wild barley,Hordeum spontaneum Koch

Populations of wild barley, Hordeum spontaneum Koch, were collected in two distinct climatic regions, desert and Mediterranean. Plants from five desert and five Mediterranean populations were compared and contrasted for extent and structure of phenotypic variation. These same 10 and one other population from each region were analyzed for allozyme variation. In a field trial of phenotypic diversity, two phenological and 14 morphological traits were examined. Study of allozyme variation was performed using eight enzyme systems encoding for 13 loci. Plants from the desert and Mediterranean regions were significantly different in seven of 16 phenotypic traits, exhibited a high (30%) interregional component of phenotypic variation, and showed a high degree of segregation on a principal component scattergram indicating ecotypic differentiation. Mediterranean populations were twice as variable as desert populations in reproductive growth parameters (stem and spike length) and grain filling (spikelet weight), but half as variable for onset of reproduction. The extent and structure of phenotypic and allozyme variation did not match. The Mediterranean and desert populations did not differ in amount of allozyme variation as estimated by mean number of alleles per locus, effective number of alleles, polymorphism, and gene diversity (n(a), n(e), P, and H(e)), did not segregate on the basis of population genetic distances, and exhibited a low proportion of interregion allozyme diversity (2%). No effect of selection on allozyme distribution was detected. Our results suggest that the adaptation of plants originating from desert and Mediterranean environments is reflected in phenotypic but not in allozyme variation.     

From micro- to macroevolution: brood parasitism as a driver of phenotypic diversity in birds

A fundamental question in biology is how diversity evolves and why some clades are more diverse than others. Phenotypic diversity has often been shown to result from morphological adaptation to different habitats. The role of behavioral interactions as a driver of broadscale phenotypic diversity has received comparatively less attention. Behavioral interactions, however, are a key agent of natural selection. Antagonistic behavioral interactions with predators or with parasites can have significant fitness consequences, and hence act as strong evolutionary forces on the phenotype of species, ultimately generating diversity between species of both victims and exploiters. Avian obligate brood parasites lay their eggs in the nests of other species, their hosts, and this behavioral interaction between hosts and parasites is often considered one of the best examples of coevolution in the natural world. In this review, we use the coevolution between brood parasites and their hosts to illustrate the potential of behavioral interactions to drive evolution of phenotypic diversity at different taxonomic scales. We provide a bridge between behavioral ecology and macroevolution by describing how this interaction has increased avian phenotypic diversity not only in the brood parasitic clades but also in their hosts.     

The stability of P in coral reef fishes

The constancy of phenotypic variation and covariation is an assumption that underlies most recent investigations of past selective regimes and attempts to predict future responses to selection. Few studies have tested this assumption of constancy despite good reasons to expect that the pattern of phenotypic variation and covariation may vary in space and time. We compared phenotypic variance-covariance matrices (P) estimated for populations of six species of distantly related coral reef fishes sampled at two locations on Australia's Great Barrier Reef separated by more than 1000 km. The intraspecific similarity between these matrices was estimated using two methods: matrix correlation and common principal component analysis. Although there was no evidence of equality between pairs of P, both statistical approaches indicated a high degree of similarity in morphology between the two populations for each species. In general, the hierarchical decomposition of the variance-covariance structure of these populations indicated that all principal components of phenotypic variance-covariance were shared but that they differed in the degree of variation associated with each of these components. The consistency of this pattern is remarkable given the diversity of morphologies and life histories encompassed by these species. Although some phenotypic instability was indicated, these results were consistent with a generally conserved pattern of multivariate selection between populations.     

中亚热带赤皮青冈天然种群表型多样性分析

赤皮青冈(Quercus gilva)是我国中亚热带地区极具经济价值的珍贵用材树种。为揭示其表型多样性与变异规律以及影响表型变异的关键地理气候因子，该研究以14个赤皮青冈天然种群115个单株为材料，对其15个树体和叶片性状进行测量，并采用巢式方差分析、表型分化系数分析、多样性指数分析、相关性分析、主成分分析以及聚类分析等方法，探究赤皮青冈的表型变异规律及其与地理气候因子的相关性。结果表明：(1)赤皮青冈表型多样性水平较高，15个表型性状的变异系数和Shannon-Wiener指数平均值分别为35.070%和1.998,14个种群的变异系数在14.94%(洞口)～35.56%(龙山)之间、Shannon-Wiener指数在1.127(松阳)～1.980(常宁)之间。(2)15个表型性状在种群间和种群内均存在极显著差异(P<0.01),种群平均表型分化系数为41.491%,表型变异主要来源于种群内。(3)相关性分析发现，赤皮青冈部分性状间存在显著或极显著相关性，表型性状与地理因子间相关性不明显，降水是影响赤皮青冈表型性状的主要气候因子。(4)主成分分析发现，基于11个表型可提炼出4个...     

CRYPTIC DIVERSITY IN PHYTOPLANKTON CULTURES IS REVEALED USING A SIMPLE PLATING TECHNIQUE1

A simple technique has been developed to probe the occurrence of cryptic genetic diversity in populations of laboratory‐maintained phytoplankton cultures. This agarose‐based method allows the investigator to plate a broad range of fragile algae, including representatives of the Raphidophyceae, Synurophyceae, Prymnesiophyceae, and Dinophyceae. Heterosigma akashiwo (Hada) Hada ex Y. Hara et Chihara was selected as a model system for our genetic diversity study. Further optimization of the plating technique for this alga demonstrated that colony formation was independent of the physiological state of the parent culture and yet dependent on incident light intensity. The density at which cells were plated affected colony formation and the rate of growth, with intermediate densities (～10³ cells per plate) performing best. High‐metal stress was used as the selective screen for assessing genetic variability within a single H. akashiwo culture. To this end, “clonal” lines (quotation marks used to indicate that within‐clone diversity was expected) were generated from individual plated colonies, and their tolerance was measured by plating on selective medium. Results of these experiments suggest the following: (i) “clonal” lines generated from a single H. akashiwo culture displayed a significant variation in stress tolerance; (ii) “clonal” lines chosen for their ability to grow on selective plates retained this tolerance in the absence of stress, indicating that the observed variation is heritable; and (iii) genetic variation is continually generated in growing cultures. Our results are consistent with a conceptual model, presented here, in which stress tolerance among the individuals in a culture has a genetic basis that varies over a continuous spectrum.     

The molecular population genetics of regulatory genes

Regulatory loci, which may encode both trans acting proteins as well as cis acting promoter regions, are crucial components of an organism's genetic architecture. Although evolution of these regulatory loci is believed to underlie the evolution of numerous adaptive traits, there is little information on natural variation of these genes. Recent molecular population genetic studies, however, have provided insights into the extent of natural variation at regulatory genes, the evolutionary forces that shape them and the phenotypic effects of molecular regulatory variants. These recent analyses suggest that it may be possible to study the molecular evolutionary ecology of regulatory diversification by examining both the extent and patterning of regulatory gene diversity, the phenotypic effects of molecular variation at these loci and their ecological consequences.     

灯盏花种质资源群体表型多样性研究

以采集自云南和贵州的21份灯盏花种质资源为材料,观测了它们的群体表型性状特征,并分析了这些表型性状的遗传多样性.结果表明:灯盏花种质资源的表型质量性状在居群内外均有丰富变异,不同质量性状的频率不同,并以多叶型的植株、绿色的茎、疏的茎毛、倒披针型的基生叶、全缘叶、锐尖的叶尖、花色淡紫和黄色的管状花冠口等为代表性表型性状.居群内各数量性状间以单株基生叶数和单株分枝数变异系数较高(均超过50%),而花序直径变异系数最低(18.14%);居群间各表型性状以株高和单序管状花数变异系数较高(52.98%和41.98%),而单株基生叶数和基生叶长变异系数较低(<20%).地理类群间表型分化系数为26.58%,地理类群内表型分化系数为73.42%.灯盏花性状表型多样性指数以株高最高(2.243),以单株分枝数和单株基生叶数较低(1.723和1.874),总体平均表型多样性指数为2.028;不同地理类群的表型多样性指数为1.589~1.890,并以楚雄地区最高,曲靖地区最低.研究发现,灯盏花种质资源具有丰富的质量和数量性状变异,多数性状的地理类群内变异大于地理类群间,且表型多样性指数相对较高,对其地理类群内变异的保护和利用对灯盏花育种具有重要的意义.     

CONFLICTING SELECTION FROM AN ANTAGONIST AND A MUTUALIST ENHANCES PHENOTYPIC VARIATION IN A PLANT

The raw material for evolution is variation. Consequently, identifying the factors that generate, maintain, and erode phenotypic and genetic variation in ecologically important traits within and among populations is important. Although persistent directional or stabilizing selection can deplete variation, spatial variation in conflicting directional selection can enhance variation. Here, we present evidence that phenotypic variation in limber pine (Pinus flexilis) cone structure is enhanced by conflicting selection pressures exerted by its mutualistic seed disperser (Clark's nutcracker Nucifraga columbiana) and an antagonistic seed predator (pine squirrel Tamiasciurus spp.). Phenotypic variation in cone structure was bimodal and about two times greater where both agents of selection co‐occurred than where one (the seed predator) was absent. Within the region where both agents of selection co‐occurred, bimodality in cone structure was pronounced where there appears to be a mosaic of habitats with some persistent habitats supporting only the seed disperser. These results indicate that conflicting selection stemming from spatial variation in community diversity can enhance phenotypic variation in ecologically important traits.     

Heterochrony, maternal effects, and phenotypic variation among sympatric pupfishes

Variation in ontogeny can produce phenotypic variation both within and among species. I investigated whether changes in timing and rate of growth were a source of phenotypic variation in a putative incipient species group of pupfish (Cyprinodon spp.). On San Salvador Island, Bahamas, sympatric forms of pupfish differ in morphology but show only partial reproductive isolation in the laboratory. Offspring from two forms and two geographical areas and their hybrids were bred in the laboratory, and ontogenetic trajectories of their feeding morphology were followed until maturity. In the Bahamian pupfish the two forms grow along similar size but not shape trajectories. Two heterochronic parameters, onset and rate of growth, alter shape trajectories in the Bahamian pupfish. Similar forms from different geographical areas (Florida and the Bahamas) grow along parallel shape trajectories, differing only in one heterochronic parameter, the onset shape. Hybrids within and between the pupfish forms produced intermediate feeding morphologies that were influenced by their maternal phenotype, suggesting that maternal effects may be a source of phenotypic variation in shape that can persist to maturity. In Cyprinodon, small changes in multiple heterochronic parameters translate into large phenotypic differences in feeding morphology.     

Phenotypic variations in cones and seeds of natural Pinus kesiya var. langbianensis populations in Yunnan Province,China

以云南省思茅松(Pinus kesiya var. langbianensis)天然分布区的11个种群的16个种实性状为研究对象, 采用巢式方差分析、变异系数、相关分析和非加权配对算术平均法(UPGMA)等多种分析方法, 探讨思茅松种群间和种群内的表型变异。结果表明: 思茅松种实表型性状在种群间和种群内均存在着较丰富的差异, 种群内的变异(54.76%)大于种群间的变异(10.44%), 种群间平均分化系数为11.95%, 分化程度相对较小。球果总种子数的平均变异系数最高(35.51%), 其次是球果质量(35.1%), 种子大小的平均变异系数最小(8.86%), 成为最稳定的种实性状; 景谷县的表型多样性最丰富, 景洪市则最小。球果和种子大部分表型性状之间存在显著或极显著相关, 其中球果长和球果质量越大, 种鳞长、种子长、种翅长、千粒重、球果总种鳞数和球果总种子数就越大。生态因子中, 年平均气温对表型性状影响最大, 其次是1月平均气温和>5 ℃积温。利用种群间聚类分析可以把思茅松的11个种群分为2类4个亚类, 表型性状依据地理距离进行聚类, 聚类结果与年降水量和>5 ℃积温相关性显著。     

Genetic variation for antibiotic persistence in Escherichia coli

Bacterial persistence describes a heterogeneous response to antibiotics in clonal populations of bacteria due to phenotypic variation within the population, with a small proportion of cells surviving treatment even at very high concentrations of drug. The aim of this study was to determine whether different natural isolates of Escherichia coli, selected at random from a collection representing the spectrum of genetic diversity in the species, generate different fractions of persister cells. Despite comparable minimum inhibitory concentrations (MICs) to the antibiotics between the different strains, highly significant variation was observed in persister fractions following exposure to ampicillin, streptomycinm, or norfloxacin. Survival following treatment with one drug did not, however, correlate with survival against another. Finally, using competition assays we quantify fitness benefits of persistence. These results show that different strains of E. coli vary markedly in their response to antibiotics despite comparable genetic susceptibility and indicate different mechanisms of evolved persistence to different antibiotics.     

Compensatory Evolution and the Origins of Innovations

Cryptic genetic sequences have attenuated effects on phenotypes. In the classic view, relaxed selection allows cryptic genetic diversity to build up across individuals in a population, providing alleles that may later contribute to adaptation when co-opted—e.g., following a mutation increasing expression from a low, attenuated baseline. This view is described, for example, by the metaphor of the spread of a population across a neutral network in genotype space. As an alternative view, consider the fact that most phenotypic traits are affected by multiple sequences, including cryptic ones. Even in a strictly clonal population, the co-option of cryptic sequences at different loci may have different phenotypic effects and offer the population multiple adaptive possibilities. Here, we model the evolution of quantitative phenotypic characters encoded by cryptic sequences and compare the relative contributions of genetic diversity and of variation across sites to the phenotypic potential of a population. We show that most of the phenotypic variation accessible through co-option would exist even in populations with no polymorphism. This is made possible by a history of compensatory evolution, whereby the phenotypic effect of a cryptic mutation at one site was balanced by mutations elsewhere in the genome, leading to a diversity of cryptic effect sizes across sites rather than across individuals. Cryptic sequences might accelerate adaptation and facilitate large phenotypic changes even in the absence of genetic diversity, as traditionally defined in terms of alternative alleles.     

PHENOTYPIC VARIATION AND GENOTYPIC DIVERSITY IN A PLANKTONIC POPULATION OF THE TOXIGENIC MARINE DINOFLAGELLATE ALEXANDRIUM TAMARENSE (DINOPHYCEAE)1

Multiple clonal isolates from a geographic population of Alexandrium tamarense (M. Lebour) Balech from the North Sea exhibited high genotypic and phenotypic variation. Genetic heterogeneity was such that no clonal lineage was repeatedly sampled according to genotypic markers specified by amplified fragment length polymorphism (AFLP) and microsatellites. Subsampling of genotypic data from both markers showed that ordination of individuals by pair‐wise genetic dissimilarity indices was more reliable by AFLP (482 biallelic loci) than by microsatellites (18 loci). However, resulting patterns of pair‐wise genetic similarities from both markers were significantly correlated (Mantel test P < 0.005). The composition of neurotoxins associated with paralytic shellfish poisoning (PSP) was also highly diverse among these isolates and allowed clustering of toxin phenotypes based on prevalence of individual toxins. Correlation analysis of pair‐wise relatedness of individual clones according to PSP‐toxin profiles and both genotypic characters failed to yield close associations. The expression of allelochemical properties against the cryptophyte Rhodomonas salina (Wis?ouch) D. R. A. Hill et Wetherbee and the predatory dinoflagellate Oxyrrhis marina Dujard. manifested population‐wide variation of responses in the target species, from no visible effect to complete lysis of target cells. Whereas the high genotypic variation indicates high potential for adaptability of the population, we interpret the wide phenotypic variation as evidence for lack of strong selective pressure on respective phenotypic traits at the time the population was sampled. Population markers as applied here may elucidate the ecological significance of respective traits when followed under variable environmental conditions, thereby revealing how variation is maintained within populations.     

Variation in growth in the blue tit (Parus caeruleus)

The pattern and amount of phenotypic and genetic variation in growth was analysed using the infinite-dimensional model in natural populations of the blue tit (Parus caeruleus). A size-index was used to analyse patterns of variation and covariation across ages (2, 5, 8, 11 and 14 days). Genetic variation was analysed using mother-, father-, and midparent-offspring regressions in the blue tit. Phenotypic variation in growth was limited to a few dimensions only, while heritabilities were close to zero at all ages except at 2 days when a significant mother-offspring relation was found. The phenotypic variance-covariance matrix over ages was found to be singular, which suggests that there are trajectories for which there is no phenotypic variation, and which therefore they cannot evolve. The phenotypic growth trajectory associated with the largest amount of variation basically showed a high to moderately high covariation across ages. These results have macroevolutionary implications in terms of the outcome of selection which generally will be in terms of overall size changes but with a slow rate of change due to low heritabilities; an outcome consistent with macro-evolutionary patterns of morphological variation in birds. A simulation study supported the conclusion that high covariances among traits and ages can impose considerable constraint on a microevolutionary scale.     

Effect of habitat quality and phenotypic variation on abundance- and trait-based early warning signals of population collapses

Loss of resilience in population numbers in response to environmental perturbations may be predicted with statistical metrics called early warning signals (EWS) that are derived from abundance time series. These signals, however, have been shown to have limited success, leading to the development of trait-based EWS that are based on information collected from phenotypic traits such as body size. Experimental work assessing the efficacy of EWS under varying ecological and environmental factors are rare. In addition, disentangling how such warning signals are affected under varying ecological and environmental factors is key to their application in biological conservation. Here, we experimentally test how different rates of environmental forcing (i.e. warming) and varying ecological factors (i.e. habitat quality and phenotypic diversity) affected population stability and predictive power of early warning signals of population collapse. We analyzed population density and body size time series data from three phenotypically different populations of a protozoan ciliate Askenasia volvox in two levels of habitat quality subjected to three different treatments of warming (i.e. no warming, fast warming and slow warming). We then evaluated how well abundance- and trait-based EWS predicted population collapses under different levels of phenotypic diversity, habitat quality and warming treatments. Our results suggest that habitat quality and warming treatments had more profound effects than phenotypic diversity had on both population stability and on the performance of abundance-based signals of population collapse. In addition, trait-based EWS generally performed well, were reliable and more robust in forecasting population collapse than abundance-based EWS, regardless of variation in environmental and ecological factors. Our study points towards the development of a predictive framework that includes information from phenotypic traits such as body size as an indicator of loss of resilience of ecological systems in response to environmental perturbations.