Phylogenetic relationships among Puccinellia and allied genera of Poaceae as inferred from chloroplast DNA restriction site variation

A cladistic analysis of chloroplast DNA restriction site variation among accessions of Catabrosa P. Beauv., Phippsia (Trin.) R. Br., Sclerochloa P. Beauv., and Puccinellia Pari, resolved a monophyletic Puccinellia, with Sclerochloa as its sister group, Phippsia the sister of the Puccinellia + Sclerochloa clade, and Catabrosa situated more distantly. These results suggest that the taxonomic fusion of Phippsia and Puccinellia, which has been proposed in light of the existence of natural hybrids between them (currently recognized as the nothogenus × Pucciphippsia Tsvelev), would yield a grouping that would not be monophyletic unless Sclerochloa also was included. The set of restriction site characters that resolve these relationships provides minimal support for species groupings within Puccinellia, and the groupings that are resolved are inconsistent in some cases with species boundaries as determined by morphology and isozymes.     

Reuse of voucher specimens provides insights into the genomic associations and taxonomic value of wing colour and genitalic differences in a pest group (Lepidoptera: Tortricidae: Choristoneura)

Subtle morphological differences can be essential to diagnosing closely related species, and an understanding of the genetic basis of these characters can contribute to understanding their divergences. We used voucher specimens from previous genetic analyses of population structure to subsequently analyse genome-wide associations linking morphology to genetic variation in spruce budworms, a group of economically important and morphologically similar forest pests. In particular, we assessed the taxonomic value and genetic architecture of two morphological traits (wing pattern and genitalic spicule abundance) that have been reported to differ among spruce budworm species. Our results suggest that phallic spicule number has greater taxonomic utility than wing pattern for distinguishing Choristoneura fumiferana (Clemens) from Choristoneura occidentalis occidentalis Freeman and Choristoneura occidentalis biennis Freeman. However, there was considerable overlap among taxa for all phenotypic characters analysed. In a genome-wide association study, wing pattern variation was significantly associated with four single nucleotide polymorphism (SNP) loci, including two adjacent SNPs. One SNP was flanked by sequence resembling RNA-directed DNA polymerase from mobile element jockey-like. This locus is a promising candidate for the study of wing pattern development in spruce budworms, as jockey-like transposable elements and polymerases have documented roles in wing spot production in other Lepidoptera. Our study links classical taxonomic characters and genomic data to provide insights into the potential genetic architecture of species differences. It also demonstrates previously untapped morphological and taxonomic value in voucher specimens from earlier molecular genetic analyses.     

Phenotypic plasticity and character differentiation in a subdivided population ofIris pumila (Iridaceae)

Variation patterns in phenotypic plasticity and broad sense heritability of 26 characters were examined within and among closely adjacent habitats of the bearded iris,Iris pumila. It was found thatI. pumila has considerable differentiation for phenotypic plasticity and genetic variation over short distances. An analysis of relationships between character differentiation and phenotypic plasticity suggests that they could have evolved independently. Possible mechanisms for maintaining local differentiation of the observed plastic and genetic variation are also discussed.     

Phenotypic plasticity in Philonotis fontana (Bryopsida: Bartramiaceae)

Abstract

Gametophytes from six populations of the moss Philonotis fontana (Hedw.) Brid. were grown under two light and two water regimes in order to assess the effects of these environmental factors on gametophytic architecture and leaf and leaf-cell dimensions. Both light and water affectedgrowth, but the light treatments had a greater effect, and on more characters, than did the water treatments. Significant population effects under common garden conditions point to genetic variation for several traits, and population × environmental treatment interactions demonstratedgenetic variation for patterns of phenotypic plasticity, i.e. plants differed in their 'norms of reaction'. Variation among populations in leaf dimensions tended to have a strong genetic component (20–30% of the total variation), whereas cell dimensions showed relatively little geneticvariation (<10% of the total).     

DEVELOPMENTAL PLASTICITY,GENETIC VARIATION,AND THE EVOLUTION OF ANDROMONOECY IN SOLANUM HIRTUM (SOLANACEAE)

Studies of andromonoecious species have shown that sex expression (proportions of hermaphrodite and staminate flowers) is quite variable. It is not known, however, whether this variation is due to variation among individuals for genetically fixed patterns of allocation to staminate and hermaphrodite flowers (population level variation) and/or to developmental plasticity of individuals in a heterogeneous environment (organismal level variation). Distinguishing between these two levels of variation is important for understanding the evolution of andromonoecy. This study investigates levels of variation in sex expression in the andromonoecious Solanum hirlum. Sex expression in this species is shown to be plastic among individuals of the same genotype (organismal level variation) and determined, in part, by the resource status of the individual. Among the genotypes examined there is also genetic variation for developmental plasticity. Thus, developmental plasticity can potentially respond to selection, and the evolution of this developmental system may have been instrumental in the establishment and maintenance of andromonoecy in S. hirtum.     

Cryptic diversity,intraspecific phenetic plasticity and recent geographical translocations in Branchiomma (Sabellidae,Annelida)

The importance of identifying biological diversity accurately and efficiently is becoming more evident. It is therefore critical to determine the species boundaries between closely related taxa and to establish diagnostic characters that allow us to define species. This is not an easy task when species exhibit high intraspecific phenotypic plasticity or when distinct evolutionary lineages with an unusually large amount of genetic distinctiveness show no apparent morphological diversity (cryptic species). These phenomena appear to be common in the genus of fan worms Branchiomma (Sabellidae, Annelida), and consequently, taxonomic errors are widespread in the group. Moreover, some Branchiomma species have been unintentionally translocated outside the area where natural range extension is expected, increasing the taxonomic problems. We have performed a range of analytical methods including genetic distances, Bayesian inference, maximum likelihood, maximum parsimony, statistical parsimony analyses and general mixed Yule coalescent model to clarify the taxonomic status and assess the species boundaries of Branchiomma in Australia. This study shows that the traditional diagnostic morphological features are greatly homoplastic. Results also indicate that the diversity of Branchiomma in Australia is higher than previously reported and evidence some cases of high phenetic plasticity (in features previously considered as stable within species), high intraspecific genetic variability, cryptic species and several unexpected cases of translocations.     

Morphological flexibility across an environmental gradient in the epiphytic orchid,Tolumnia variegata: complicating patterns of fitness

Deceit‐pollinated orchid species show substantial variation in floral traits, which may be maintained by genetic drift or various forms of selection, or may reflect phenotypic plasticity. We explored how much plasticity occurs in both vegetative and floral traits of Tolumnia variegata (Oncidiinae, Orchidaceae) across two different light environments in Puerto Rico using data from a reciprocal transplant experiment. We also examined how fruit set, a measure of reproductive success and a surrogate for fitness, is associated with this morphological variation, and whether it changes over time. Tolumnia variegata responded to environmental variables in multiple ways. Vegetative characters were more plastic than those associated with sexual reproduction. Transplant effects accounted for significant variation in flower length, lip length, number of inflorescences, peduncle length, leaf length and the total number of ramets, but responses were not always consistent among years. Phenotypic selection on morphological characters was dependent on plant location. The trends detected were complex, and often inconsistent across years, probably as a result of wetter and drier years than average. Overall fruit set was quite variable among plants, averaging 15%, with no significant differences among sun and shade plants. Although reproductive success was similar among sites, habitat heterogeneity and annual variation had an effect on morphological expression, which sometimes modified the trajectories of phenotypic selection. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 431–446.     

Bryophyte County Floras

Abstract

Experimental study of Pohlia populations that regularly produce axillary bulbils in Britain has shown that there are seven species present. The distinguishing bulbil characters of field populations of each species are retained when the plants are cultivated under uniform conditions, and can be used as a valid taxonomic criterion. Variation in bulbil morphology within and between populations of P. proligera is due to a combination of genetic, environmental and developmental variation. Bulbils show considerable phenotypic plasticity in P. drummondii but in the other five species studied variation is largely or entirely developmen tal.     

THE GENETIC BASIS OF THE ECOLOGICAL AMPLITUDE OF SPARTINA PATENS. II. VARIANCE AND CORRELATION ANALYSIS

Reciprocal transplantations of Spartina patens genotypes from adjacent salt marsh, swale, and dune habitats provided evidence for genetic differentiation among subpopulations, due at least in part to contrasting selection regimes. Genet survival in the different habitats was related to the amount of genetic divergence. In the dune habitat, marsh ramets showed the lowest survival, swale ramets showed intermediate survival, and dune ramets showed the highest survival. This relationship was not reciprocal, however. The marsh habitat afforded an environment where survival was maximal for all genotypes. Thus, by comparison, the dune environment appeared to impose a more intense selection pressure, and the swale an intermediate selection pressure on Spartina patens. In each site resident genotypes tended to show greater relative fitness than aliens. This evidence for genetic divergence corroborates that previously reported on morphometric (Silander and Antonovics, 1979) and allozymic traits (Silander, 1984). High levels of phenotypic plasticity may permit greater adaptation to the spatially and temporally heterogeneous environment occupied by S. patens than would genetic variation alone. Dune and swale genets were more phenotypically plastic across traits examined than were marsh genotypes. The higher plasticity in these peripheral subpopulations may confer increased fitness among residents and compensate for observed declines in genetic variation. A slight decrease in genetic variability was evident from marsh to dune subpopulations. However, since the differences in genetic variation among subpopulations were small, and disparities did occur, it is unlikely that evolutionary divergence is retarded primarily by a lack of genetic variability in the characters considered. Evidence is presented to indicate that evolutionary divergence among subpopulations may be retarded by negative or unfavorable correlations among characters being selected simultaneously. These negative correlations may increase extinction probabilities in small peripheral populations, such as those represented by the dune or swale, and are likely to lower fitness. Based on these observations, I hypothesize that further microevolution may be retarded in peripheral dune and swale subpopulations, primarily by unfavorable genetic correlation structures among fitness components or characters under simultaneous selection. Contributing factors may include lowered genetic variance and higher levels of phenotypic plasticity.     

Taxonomic importance of seed macro‐ and micro‐morphology in Abelmoschus (Malvaceae)

Seed morphology of Abelmoschus is known to be variable, but patterns of variation have never been critically studied. We studied seed macro‐ and micro‐morphological characters, including seed shape/size, seed coat pattern and trichome density/structure in multiple samples to evaluate the taxonomic significance of seed characters. Among the studied characters, seed shape and trichome structure were found to have major taxonomic importance and proved to be valuable characters for separating taxa. Two main seed types were present: seeds with deciduous trichomes and seeds with persistent trichomes. These characters offer significant evidence to the distinctness of certain species (A. esculentus, A. moschatus subsp. moschatus, A. moschatus subsp. tuberosus, A. crinitus and A. angulosus). Further, our results indicate that A. moschatus subsp. tuberosus should be maintained as a separate subspecies while A. manihot subsp. tetraphyllus var. pungens may be merged in A. angulosus. No significant intraspecific variation was observed, except in A. esculentus. We conclude that seed coat sculpturing and seed trichomes do indeed provide stable and diagnostic characters for many morphologically closely related taxa of Abelmoschus and that LM/SEM techniques can be useful in solving systematic problems and management of Abelmoschus genetic resources.     

Consistent and variable leaf anatomical characters in Carex (Cyperaceae)

The anatomy and morphology of leaves in Carex have the potential to be taxonomically useful. However, studies on the variability of leaf characteristics in the genus are sparse. Researchers therefore risk using leaf anatomical characters without the knowledge of whether they are consistent in a species. We examined 22 qualitative and seven quantitative leaf anatomy characters from transverse leaf sections to test their consistency across 11 Carex spp. The characters were clearly described and primarily microscopic. Some characters were found to exhibit high levels of intraspecific variation, whereas other characters exhibited high levels of consistency in a species, including the shape of the leaf section, the density of papillae and the size of epidermal cells. Caution must be applied when choosing leaf anatomy to delimit taxa because of the intraspecific variability found in some characters, but sufficient numbers of invariant characters exist to provide useful taxonomic separation. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 371–384.     

Biosystematic Studies on Adenophora potaninii Korsh. Complex (Campanulaceae). Ⅰ. Phenotypic Plasticity

Phenotypic plasticity is the environmental modification of genotypic expression and an important means by which individual plants respond to environmental heterogeneity. The study of phenotypic plasticity in the genus Adenophora, which is very complicated taxo nomically because of great morphological variation, proves to be helpful in both investigating the phenotypic variation so as to evaluate potential taxonomic value of their characters and providing important sources of information on the variation, adaptation and evolution of the genus. Twenty-three populations representing all the six species in Adenophora potaninii complex were transplanted into the garden. Of them six populations were selected for study ing their performance in the field and in the garden, in addition to cultivation experiment under different treatments. The results show that there exists considerable developmental plasticity in some leaf, floral and capsule characters. In particular, the leaf shape and length of calyx lobe display significant developmental variation with the maximum being three times as great as the minimum, which is noteworthy because they were previously considered as diagnostic. The characters of root, caudex, stem and inflorescence are found to be very plastic, especially the root diameter, the number of stems, stem height and inflorescence length with great environmental plasticity. In addition, the populations from different habi tats show distinct amounts of plasticity. On the contrary, the characters of leaf, floral, cap sule and seed are less influenced by environments. It seems that the considerable variation in the characters of leaf is attributed mainly to genetic differences. Finally, the phenotypic plasticity of morphological characters of A. potaninii complex and its taxonomic significanceis discussed.     

Pollen diameter and fertility in nine species ofPuccinellia (Poaceae)

Diameter and fertility of pollen grains were surveyed in nine species ofPuccinellia Parl. (Poaceae), mainly from the Iberian Peninsula, allowing information about reproductive behaviour and biological characteristics of pollen of these taxa. Maximum diameter was measured with an image processor and fertility was evaluated by staining the grains with Müntzing's mixture. Significant differences in both characters were found between the taxa. In consequence, maximum diameter and fertility proved to have some taxonomic relevance inPuccinellia.     

泡沙参复合体（桔梗科）的物种生物学研究：Ⅰ表型的可塑性

表型可塑性是生物变异中由环境引起的一种变异,是植物适应的一种重要方式。对沙参属这样一个形态上复杂多变、分类上很难处理的类群,研究其表型可塑性不仅为探讨性状变异、判断其系统学意义及选择可靠的分类性状提供了有益的资料,而且有助于揭示沙参属植物变异、适应和进化的机制。本文从泡沙参复合体中选择了6个居群,利用播种和移栽试验,通过对不同个体和居群在一致条件下的表现及野外和移栽后的对比,对根、茎、叶、花和果等形态性状的表型可塑性进行了初步的观测分析。结果表明,一些叶片、花部和果实性状具有较大的发育可塑性,尤其是叶形、花萼裂片不仅发育变化大,而且随发育过程定向变化。环境可塑性较大的性状主要是根、茎、花序分枝等性状,而叶片、花部、果实和种子性状的环境饰变能力都较小。最后,对泡沙参复合体形态性状的变异从发育可塑性和环境可塑性的角度进行了讨论。     

Patterns of genetic diversity vary among shoot and root functional traits in Norway spruce Picea abies along a latitudinal gradient

Roots constitute a major segment of plant biomass, and variation in belowground traits in situ correlates with environmental gradients at large spatial scales. Local adaptation of populations maintains intraspecific genetic variation in various shoot traits, but the contribution of genetic factors to adaptation to soil heterogeneity remains poorly known. I established a common-garden experiment with three Norway spruce Picea abies populations sampled between 60° and 67° N in Finland, each represented by 13 or 15 maternal families, to determine whether belowground traits are as genetically differentiated among populations as those in the shoot along a collective latitudinal gradient of temperature and soil heterogeneity. Two growing season simulations enabled testing for among-population differences in phenotypic plasticity. I phenotyped 777 first-year seedlings from shoot to root to capture functional traits that may influence survival in the wild: autumn phenology, shoot growth, root system size, root architecture, root morphology and growth allocation. All traits exhibited within-population genetic diversity, but among-population differentiation ranged from strong in shoot traits to nonexistent in root system architecture and morphology that are scaled to root system size. However, latitudinal trends characterised root-to-shoot ratio and root tip-to-shoot ratio that account for among-population differences in aboveground growth. Overall trait variability was multidimensional with variable among- versus within-population trends: for example, phenology and shoot growth covaried across populations, but their association within individual populations was variable. Shoot growth correlated positively with root system size, but not with root architecture or morphology. Finally, the two higher-latitude populations exhibited greater phenotypic plasticity in shoot traits and growth allocation. The results demonstrate varying patterns of genetic variation in functional traits of Norway spruce in the boreal zone, suggesting simultaneous adaptation to multiple environmental factors. Functional traits that exhibit phenotypic plasticity, genetic diversity and little covariation will promote long-term survival of populations in fluctuating environments.     

Reaction norms of Arabidopsis (Brassicaceae). III. Response to nutrients in 26 populations from a worldwide collection

The study of phenotypic plasticity, the ability of a given genotype to express different phenotypes as environments change, is becoming a central focus of ecological genetics and evolutionary theory. To help address the most pressing questions about plasticity (its genetic control, ecological relevance, and macroevolutionary consequences) we advocate the use of Arabidopsis thaliana (and eventually other related species of the same genus) as a model system. In this study we present experimental data concerning: (a) the extent of reaction norm variation to two levels of nutrients in a worldwide collection of 26 A. thaliana populations; and (b) the existence of multivariate associations among key phenotypic characters, and their reaction to changes in the environment. We found significant among-population genetic variation for eight of the nine traits measured, as well as plasticity in four traits. Five traits showed significant differences in genetic variation between the two environments. The multivariate association of the nine traits defines four major groups of covarying characters, each of which may be plastic or not, depending on the particular population. The use of populations that can be easily obtained by any researcher, because they are part of a worldwide collection, implies that it will be easy to build on our results during future investigations of phenotypic plasticity in this species.     

Genetic and phenotypic variation in diet breadth in a generalist herbivore

Summary The genetic and plastic components of polyphagy were investigated in a population ofLymantria dispar, the gypsy moth. A simple genetic experiment assessed the expression of (1) genetic variability in life history traits within each of four environments, (2) genetic variability in diet breadth, expressed as a change in the ranks of family performance across hosts, and (3) homeostasis (equivalent performance by a family across hosts) versus phenotypic plasticity (variable performance by a family across hosts). Sibs from each of 14 families, randomly selected from a single population, were reared on four diets: two natural hosts — chestnut and red oak, and two synthetic hosts — a standard laboratory diet and a low-protein version of this diet. Average population performance, measured in terms of development time and pupal weight, was better on standard laboratory diet than on low-protein diet, and was equal on chestnut and red oak for pupal weight, but better on chestnut oak for development time. Average population performance provided no information about the genetic component of host use ability. The gypsy moth expressed genetic variation in development time within each host environment and in pupal weight within natural host environments. Phenotypic plasticity was expressed by a significant number of families in development time and pupal weight across synthetic hosts and, to a lesser extent, across natural hosts. It was only across natural hosts that genetic variation in diet breadth was expressed, and this was confined to females. Genetic variability in diet breadth may be maintained in this species as a consequence of the unpredictability of its food sources.     

Multivariate analysis of morphological and anatomical characters of Calophyllum (Calophyllaceae) in South America

Calophyllum (Calophyllaceae), previously placed in Clusiaceae, is easily recognizable by its opposite entire leaves with close parallel venation alternating with resin canals. However, distinction between species has been difficult, because of infraspecific variation in tepal and stamen number and resemblance among species that share similar habitats. Here, I report the results of multivariate analyses of morphological and anatomical characters for Calophyllum in South America, and provide a taxonomic treatment for the genus in South America, the first since that of Vesque in 1893. Thirteen preliminary morphogroups were identified. Thirty‐two morphological characters of the leaf, flower and fruit from 401 specimens, and 17 anatomical leaf characters from 45 specimens were measured and analysed using principal component analyses (PCAs) and discriminant analyses (DAs). PCAs were used to find groups and DAs were used to validate those PCAs that were potential groups. Two main subgroups were identified in the general analysis. Subgroup M1 has terete stems and smaller leaves and flowers than subgroup M2, which, instead, has quadrangular stems. Only subgroup M2 showed distinctive clusters in regional and local analyses. Distinctive clusters and morphological and anatomical characters helped us to recognize four species in South America, including a new species, Calophyllum pubescens sp. nov. . In addition, a new species, Calophyllum mesoamericanum sp. nov. , is described from Central America. © 2013 The Linnean Society of London,     

Variation and evolution inLinum tenuifolium (Linaceae)

The phenetic variation inL. tenuifolium s.l. was assessed using multivariate analyses of 27 characters found to be variable within the species. These results are discussed and interpreted in the context of the reproductive biology, chromosome number and ecological responses of the taxa. Evidence suggests that both the self-compatible and tetraploid races were derived independently from a self-incompatible, diploid type. Although no taxonomic scheme is compatible with all of the evidence presented, the study supports a recent decision to recognize four taxa at subspecific level.     

Developmental thermal plasticity among Drosophila melanogaster populations

Many biotic and abiotic variables influence the dispersal and distribution of organisms. Temperature has a major role in determining these patterns because it changes daily, seasonally and spatially, and these fluctuations have a significant impact on an organism's behaviour and fitness. Most ecologically relevant phenotypes that are adaptive are also complex and thus they are influenced by many underlying loci that interact with the environment. In this study, we quantified the degree of thermal phenotypic plasticity within and among populations by measuring chill‐coma recovery times of lines reared from egg to adult at two different environmental temperatures. We used sixty genotypes from six natural populations of Drosophila melanogaster sampled along a latitudinal gradient in South America. We found significant variation in thermal plasticity both within and among populations. All populations exhibit a cold acclimation response, with flies reared at lower temperatures having increased resistance to cold. We tested a series of environmental parameters against the variation in population mean thermal plasticity and discovered the mean thermal plasticity was significantly correlated with altitude of origin of the population. Pairing our data with previous experiments on viability fitness assays in the same populations in fixed and variable environments suggests an adaptive role of this thermal plasticity in variable laboratory environments. Altogether, these data demonstrate abundant variation in adaptive thermal plasticity within and among populations.