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Plant Fitness (plant + fitness)
Selected AbstractsTowards an understanding of the mechanisms of tolerance: compensating for herbivore damage by enhancing a mutualismECOLOGICAL ENTOMOLOGY, Issue 2 2004Sharon Y. Strauss Abstract. 1. Traditionally, losses in plant fitness or yield resulting from insect damage have been redressed by reducing pest populations using insecticides or biocontrol; these approaches rely on the untested assumption that reduced plant fitness or yield is caused by diminished resources available to damaged plants. 2. By experimentally manipulating pollination and damage levels independently, it is shown that pollination, as well as lack of resources, may be limiting to damaged plants in a model insect-pollinated crop, cantaloupe. 3. With enhanced pollination, damaged plants produce as much fruit as undamaged plants, even under high damage levels. In contrast, damaged plants without supplemental pollination produced significantly less fruit than undamaged plants. 4. This approach is unique in shifting the focus away from reducing pest populations and toward enhancing mutualistic interactions. It avoids risks posed by insecticides (which also kill pollinators) and by biocontrol agents, known threats to native species. 5. Determining the mechanism underlying compensation sheds light on recovery from insect damage in both natural and managed systems. These results have a bearing on managing native plant populations suffering from pollinator declines. 6. Finally, it may be predicted that resources could limit tolerance to herbivore damage in resource-poor or high competition environments, whereas pollination may limit tolerance when resource levels are high. [source] Herbivory enhances positive effects of plant genotypic diversityECOLOGY LETTERS, Issue 5 2010John D. Parker Ecology Letters (2010) 13: 553,563 Abstract Both plant diversity and vertebrate herbivores can impact plant fitness and ecosystem functioning, however their interactions have not been explicitly tested. We manipulated plant genotypic diversity of the native plant Oenothera biennis and monitored its survivorship and lifetime fitness with and without one of its major vertebrate consumers, white-tailed deer Odocoileus virginianus. Intense but unmanipulated herbivory by meadow voles Microtus pennsylvanicus killed over 70% of nearly 4000 experimental plants. However, plants grown in genotypically diverse patches suffered fewer vole attacks and had higher survival and reproductive output than plants in monoculture. Moreover, positive effects of genotypic diversity were enhanced by the presence of deer, indicating a non-additive interaction between diversity and trophic-level complexity. Genetic selection analyses showed that the selective value of ecologically important traits depended on plant diversity and exposure to deer, demonstrating that community complexity can promote fitness through multiple ecologically and evolutionarily important feedbacks. [source] Ecological implications of plants' ability to tell the timeECOLOGY LETTERS, Issue 6 2009Víctor Resco Abstract The circadian clock (the endogenous mechanism that anticipates diurnal cycles) acts as a central coordinator of plant activity. At the molecular and organism level, it regulates key traits for plant fitness, including seed germination, gas exchange, growth and flowering, among others. In this article, we explore current evidence on the effect of the clock for the scales of interest to ecologists. We begin by synthesizing available knowledge on the effect of the clock on biosphere,atmosphere interactions and observe that, at least in the systems where it has been tested, the clock regulates gas exchange from the leaf to the ecosystem level, and we discuss its implications for estimates of the carbon balance. Then, we analyse whether incorporating the action of the clock may help in elucidating the effects of climate change on plant distributions. Circadian rhythms are involved in regulating the range of temperatures a species can survive and affects plant interactions. Finally, we review the involvement of the clock in key phenological events, such as flowering time and seed germination. Because the clock may act as a common mechanism affecting many of the diverse branches of ecology, our ultimate goal is to stimulate further research into this pressing, yet unexplored, topic. [source] THE GEOGRAPHICAL MOSAIC OF COEVOLUTION IN A PLANT,POLLINATOR MUTUALISMEVOLUTION, Issue 1 2008Bruce Anderson Although coevolution is widely accepted as a concept, its importance as a driving factor in biological diversification is still being debated. Because coevolution operates mainly at the population level, reciprocal coadaptations should result in trait covariation among populations of strongly interacting species. A long-tongued fly (Prosoeca ganglbaueri) and its primary floral food plant (Zaluzianskya microsiphon) were studied across both of their geographical ranges. The dimensions of the fly's proboscis and the flower's corolla tube length varied significantly among sites and were strongly correlated with each other. In addition, the match between tube length of flowers and tongue length of flies was found to affect plant fitness. The relationship between flower tube length and fly proboscis length remained significant in models that included various alternative environmental (altitude, longitude, latitude) and allometric (fly body size, flower diameter) predictor variables. We conclude that coevolution is a compelling explanation for the geographical covariation in flower depth and fly proboscis length. [source] PRECISION OF HERBIVORE TOLERANCE EXPERIMENTS WITH IMPOSED AND NATURAL DAMAGEEVOLUTION, Issue 3 2003Kari Lehtilä Abstract Tiffin and Inouye (2000) discussed the use of natural and imposed (controlled) damage in experiments of herbivore tolerance. They constructed a statistical model of the effect of herbivory on plant fitness, including damage level and an environmental factor as the independent factors, in which tolerance is defined as a slope of the regression line when damage level is regressed with plant fitness. They claim that while experiments with imposed damage are more accurate (i.e., they give a more correct estimate of tolerance), experiments with natural damage are more precise under a wide range of parameter values (i.e., tolerance estimates explain a larger part of variation in fitness). I show, however, that experiments with imposed damage are less precise only when an experimenter uses an experimental design that has weaker statistical power than in experiments with natural herbivory. The experimenter can nevertheless control the damage levels to optimize the experimental designs. For instance, when half of the experimental plants are left undamaged and the other half treated with maximal relevant damage level, experiments with imposed damage are almost always much more precise than experiments with natural damage. [source] Substrate specificity and inhibition of brassinin hydrolases, detoxifying enzymes from the plant pathogens Leptosphaeria maculans and Alternaria brassicicolaFEBS JOURNAL, Issue 24 2009M. Soledade C. Pedras Blackleg (Leptosphaeria maculans and Leptosphaeria biglobosa) and black spot (Alternaria brassicicola) fungi are devastating plant pathogens known to detoxify the plant defence metabolite, brassinin. The significant roles of brassinin as a crucifer phytoalexin and as a biosynthetic precursor of several other plant defences make it important in plant fitness. Brassinin detoxifying enzymes produced by L. maculans and A. brassicicola catalyse the detoxification of brassinin by hydrolysis of its dithiocarbamate group to indolyl-3-methanamine. The purification and characterization of brassinin hydrolases produced by L. maculans (BHLmL2) and A. brassicicola (BHAb) were accomplished: native BHLmL2 was found to be a tetrameric protein with a molecular mass of 220 kDa, whereas native BHAb was found to be a dimeric protein of 120 kDa. Protein characterization using LC-MS/MS and sequence alignment analyses suggested that both enzymes belong to the family of amidases with the catalytic Ser/Ser/Lys triad. Furthermore, chemical modification of BHLmL2 and BHAb with selective reagents suggested that the amino acid serine was involved in the catalytic activity of both enzymes. The overall results indicated that BHs have new substrate specificities with a new catalytic activity that can be designated as dithiocarbamate hydrolase. Investigation of the effect of various phytoalexins on the activities of BHLmL2 and BHAb indicated that cyclobrassinin was a competitive inhibitor of both enzymes. On the basis of pH dependence, sequence analyses, chemical modifications of amino acid residues and identification of headspace volatiles, a chemical mechanism for hydrolysis of the dithiocarbamate group of brassinin catalysed by BHLmL2 and BHAb is proposed. The current information should facilitate the design of specific synthetic inhibitors of these enzymes for plant treatments against blackleg and black spot fungal infections. [source] Intraspecific seed trait variations and competition: passive or adaptive response?FUNCTIONAL ECOLOGY, Issue 3 2009Cyrille Violle Summary 1The phenotype of offspring depends on the abiotic and biotic environment in which the parents developed. However, the direct effects of competition experienced by parent plants on single-seed traits are poorly documented despite their impact on plant fitness. 2We hypothesize that single-seed traits can differentially respond to the resource deficiencies of parent plants due to competition: seed quality may decrease as seed number does, magnifying the negative effects of competition for offspring (,passive response' hypothesis), or increase and then enhance offspring fitness to offset the reduction in offspring number (,adaptive response' hypothesis). Here we tested these hypotheses for four single-seed traits. We assessed the sensibility of their responses to changes in competition intensity due to species with different competitive effects and to contrasting soil nitrogen conditions. 3In a common-garden experiment, four single-seed traits related to fitness , seed mass, seed nitrogen concentration (SNC), germinability and the timing of germination , were measured on a phytometer species transplanted in 14 different neighbours grown in monoculture with and without soil nitrogen limitation. 4Under nitrogen-limiting conditions, the responses of SNC and of the timing of germination were passive and mainly related to the effects of neighbours on soil nitrogen availability, as shown by the increase in SNC with N-fixing neighbours. Within-individual seed mass variability decreased with increasing competition intensity, as an adaptive response to counterbalance the reduction in seed production. With nitrogen supplementation, competitors had no detectable effect on single-seed traits despite an overall increase in SNC and germination rate, confirming their nitrogen-dependent passive responses to competition. Germinability did not change among treatments. 5The impact of competition on single-seed traits depends on both phytometer trait identity and resource modulation by neighbours. The passive response of seed chemical composition to competitors may magnify the competitive effects on offspring. By contrast, the adaptive response of seed size variability may offset these competitive effects. As a consequence, experiments looking at the fitness consequences of competition should not only consider the effects on fitness parameters of a target plant but also on the offspring. [source] Drought changes phosphorus and potassium accumulation patterns in an evergreen Mediterranean forestFUNCTIONAL ECOLOGY, Issue 2 2007J. SARDANS Summary 1Climate models predict more extreme weather in Mediterranean ecosystems, with more frequent drought periods and torrential rainfall. These expected changes may affect major process in ecosystems such as mineral cycling. However, there is a lack of experimental data regarding the effects of prolonged drought on nutrient cycling and content in Mediterranean ecosystems. 2A 6-year drought manipulation experiment was conducted in a Quercus ilex Mediterranean forest. The aim was to investigate the effects of drought conditions expected to occur over the coming decades, on the contents and concentrations of phosphorus (P) and potassium (K) in stand biomass, and P and K content and availability in soils. 3Drought (an average reduction of 15% in soil moisture) increased P leaf concentration by 18·2% and reduced P wood and root concentrations (30·9% and 39·8%, respectively) in the dominant tree species Quercus ilex, suggesting a process of mobilization of P from wood towards leaves. The decrease in P wood concentrations in Quercus ilex, together with a decrease in forest biomass growth, led to an overall decrease (by approximately one-third) of the total P content in above-ground biomass. In control plots, the total P content in the above-ground biomass increased 54 kg ha,1 from 1999 to 2005, whereas in drought plots there was no increase in P levels in above-ground biomass. Drought had no effects on either K above-ground contents or concentrations. 4Drought increased total soil soluble P by increasing soil soluble organic P, which is the soil soluble P not directly available to plant capture. Drought reduced the ratio of soil soluble inorganic P : soil soluble organic P by 50% showing a decrease of inorganic P release from P bound to organic matter. Drought increased by 10% the total K content in the soil, but reduced the soil soluble K by 20·4%. 5Drought led to diminished plant uptake of mineral nutrients and to greater recalcitrance of minerals in soil. This will lead to a reduction in P and K in the ecosystem, due to losses in P and K through leaching and erosion, if the heavy rainfalls predicted by IPCC (Intergovernmental Panel on Climate Change) models occur. As P is currently a limiting factor in many Mediterranean terrestrial ecosystems, and given that P and K are necessary for high water-use efficiency and stomata control, the negative effects of drought on P and K content in the ecosystem may well have additional indirect negative effects on plant fitness. [source] Effects of patch size and density on flower visitation and seed set of wild plants: a pan-European approachJOURNAL OF ECOLOGY, Issue 1 2010Jens Dauber Summary 1.,Habitat fragmentation can affect pollinator and plant population structure in terms of species composition, abundance, area covered and density of flowering plants. This, in turn, may affect pollinator visitation frequency, pollen deposition, seed set and plant fitness. 2.,A reduction in the quantity of flower visits can be coupled with a reduction in the quality of pollination service and hence the plants' overall reproductive success and long-term survival. Understanding the relationship between plant population size and/or isolation and pollination limitation is of fundamental importance for plant conservation. 3.,We examined flower visitation and seed set of 10 different plant species from five European countries to investigate the general effects of plant populations size and density, both within (patch level) and between populations (population level), on seed set and pollination limitation. 4.,We found evidence that the effects of area and density of flowering plant assemblages were generally more pronounced at the patch level than at the population level. We also found that patch and population level together influenced flower visitation and seed set, and the latter increased with increasing patch area and density, but this effect was only apparent in small populations. 5.,Synthesis. By using an extensive pan-European data set on flower visitation and seed set we have identified a general pattern in the interplay between the attractiveness of flowering plant patches for pollinators and density dependence of flower visitation, and also a strong plant species-specific response to habitat fragmentation effects. This can guide efforts to conserve plant,pollinator interactions, ecosystem functioning and plant fitness in fragmented habitats. [source] What does the male function hypothesis claim?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2000Burd Paternal, rather than maternal, fitness consequences of reproductive traits are the lynchpin in many hypotheses about reproductive evolution in hermaphroditic angiosperms. These hypotheses often differ in their predictions, so that supporting or contradictory evidence for one hypothesis may not reflect similarly on another, even though both may be referred to as ,the male function hypothesis'. We provide graphical representations of four male function hypotheses from the recent literature in order to highlight their differences. We offer and explain two recommendations to reduce ambiguity in terminology: (1) male function hypotheses should address the evolution of excess flowers per se, rather than total flower number, which is usually highly plastic in modular organisms with open growth form; and (2) attention must be given to whole plant fitness, rather than fitness per flower or per inflorescence. In empirical studies, we recommend the use of path analysis to dissect the multiple pathways (through both male and female function) by which selection may act on excess flower number. [source] Developmental and spatial covariation of nutrients in growing leaves of Daphne laureola and their relationships with herbivoryNEW PHYTOLOGIST, Issue 3 2003Conchita Alonso Summary , , Here, we studied patterns of covariation of 10 leaf nutrients in expanding and mature leaves of the evergreen shrub Daphne laureola (Thymelaeaceae) in southern Spain. Changes in mean values and covariances of nutrients during leaf development may be relevant for plant fitness through herbivory if variation in leaf nutrients influences plant defoliation. , , We analysed the between-population and developmental covariation of leaf nutrients by using common principal components (CPC) analysis. We also studied the relationships between leaf nutrient covariates and natural levels of plant defoliation. , , Plants at our two study sites shared a CPC structure of covariation between concentrations of the leaf nutrients. Trends of nutrient covariation across individual plants were largely determined by between-plant variations in Ca concentration (CPC1), and by an ,overall nutrient status' gradient (CPC2) that was positively associated with major macronutrients (nitrogen, phosphorus and potassium), in both expanding and mature leaves. , , Plant defoliation was positively related to scores on CPC2 for both expanding and mature leaves, indicating greater consumption on plants with balanced, high concentrations of nitrogen, phosphorus, potassium and calcium. [source] Mycorrhizal infection and high soil phosphorus improve vegetative growth and the female and male functions in tomatoNEW PHYTOLOGIST, Issue 1 2002Jennifer L. Poulton Summary ,,To further characterize the effects of mycorrhizal infection and soil phosphorus (P) availability on plant fitness, this study examined their effects on the female and male functions, as well as vegetative growth of tomato (Lycopersicon esculentum). ,,Two cultivars of tomato were grown in a glasshouse under three treatment combinations: nonmycorrhizal, low P (NMPO); nonmycorrhizal, high P (NMP3); and mycorrhizal, low P (MPO). ,,Mycorrhizal infection and high soil P conditions improved several vegetative (leaf area, days until first flower and leaf P concentration) and reproductive traits (total flower production, fruit mass, seed number and pollen production per plant, and mean pollen production per flower). In general, mycorrhizal and P responses were greater for reproductive traits than vegetative traits. In one cultivar, these responses were greater for the male function than the female function. ,,Thus, mycorrhizal infection and high soil P conditions enhanced fitness through both the female and male functions. Similar trends were usually observed in the NMP3 and MPO treatments, suggesting that mycorrhizal effects were largely the result of improved P acquisition. [source] Seedling resistance to herbivory as a predictor of relative abundance in a synthesised prairie communityOIKOS, Issue 2 2003G. S. Burt-Smith In a laboratory experiment seedlings of 24 perennial herbaceous prairie species were offered to the omnivorous cricket Acheta domestica in an extended feeding trial. Leaf damage was monitored daily allowing an index of palatability to be calculated for each plant species. The index of palatability successfully predicted relative abundance within the same set of species in an independently-conducted study involving community assembly from seed in low-fertility plots. These results support the hypothesis that resistance to herbivory may be an important component of plant fitness in unproductive vegetation. However, the correlation between palatability and community composition may be interpreted as a positive association between traits that lead to high competitive ability and herbivory resistance. There is a need to establish whether the success of the dominant grasses at Cedar Creek arises from their superior ability to capture nitrogen from low external concentrations or is, rather, due to their superior ability to minimise nitrogen loss to herbivores. [source] Fitness and genetic variation of Viola calaminaria, an endemic metallophyte: implications of population structure and historyPLANT BIOLOGY, Issue 6 2008J.-P. Bizoux Abstract We investigated variations in genetic diversity and plant fitness in a rare endemic metallophyte of calamine soils, Viola calaminaria, in relation to population size, population connectivity and population history in order to evaluate and discuss potential conservation strategies for the species. Mean population genetic diversity (Hs = 0.25) of V. calaminaria was similar to endemic non-metallophyte taxa. Twenty-one per cent of the genetic variation was partitioned among populations and a low (9%) but significant differentiation was found among geographical regions. Our results did not support the hypothesis that the acquisition of metal tolerance may result in reduced genetic diversity, and suggested that strict metallophytes do not exhibit higher inter-population differentiation resulting from scattered habitats. There were no relationships between population genetic diversity and population size. Significant correlations were found between plant fitness and (i) population size and (ii) connectivity index. Recently-founded populations exhibited the same level of genetic diversity as ancient populations and also possessed higher plant fitness. There was no indication of strong founder effects in recently-established populations. The results suggest that the creation of habitats through human activities could provide new opportunities for conservation of this species. [source] Genetic variation in Arabidopsis thaliana for night-time leaf conductancePLANT CELL & ENVIRONMENT, Issue 8 2008MAIRGARETH A. CHRISTMAN ABSTRACT Night-time leaf conductance (gnight) and transpiration may have several adaptive benefits related to plant water, nutrient and carbon relations. Little is known, however, about genetic variation in gnight and whether this variation correlates with other gas exchange traits related to water use and/or native habitat climate. We investigated gnight in 12 natural accessions and three near isogenic lines (NILs) of Arabidopsis thaliana. Genetic variation in gnight was found for the natural accessions, and gnight was negatively correlated with native habitat atmospheric vapour pressure deficit (VPDair), suggesting lower gnight may be favoured by natural selection in drier habitats. However, there were also significant genetic correlations of gnight with daytime gas exchange traits expected to affect plant fitness [i.e. daytime leaf conductance, photosynthesis and intrinsic water-use efficiency (WUEi)], indicating that selection on daytime gas exchange traits may result in indirect selection on gnight. The comparison of three NILs to their parental genotypes identified one quantitative trait locus (QTL) contributing to variation in gnight. Further characterization of genetic variation in gnight within and among populations and species, and of associations with other traits and native habitats will be needed to understand gnight as a putatively adaptive trait. [source] Consumptive emasculation: the ecological and evolutionary consequences of pollen theftBIOLOGICAL REVIEWS, Issue 2 2009Anna L. Hargreaves ABSTRACT Many of the diverse animals that consume floral rewards act as efficient pollinators; however, others ,steal' rewards without ,paying' for them by pollinating. In contrast to the extensive studies of the ecological and evolutionary consequences of nectar theft, pollen theft and its implications remain largely neglected, even though it affects plant reproduction more directly. Here we review existing studies of pollen theft and find that: (1) most pollen thieves pollinate other plant species, suggesting that theft generally arises from a mismatch between the flower and thief that precludes pollen deposition, (2) bees are the most commonly documented pollen thieves, and (3) the floral traits that typically facilitate pollen theft involve either spatial or temporal separation of sex function within flowers (herkogamy and dichogamy, respectively). Given that herkogamy and dichogamy occur commonly and that bees are globally the most important floral visitors, pollen theft is likely a greatly under-appreciated component of floral ecology and influence on floral evolution. We identify the mechanisms by which pollen theft can affect plant fitness, and review the evidence for theft-induced ecological effects, including pollen limitation. We then explore the consequences of pollen theft for the evolution of floral traits and sexual systems, and conclude by identifying key directions for future research. [source] Fruit Traits in Baboon Diet: A Comparison with Plant Species Characteristics in West AfricaBIOTROPICA, Issue 3 2010Britta K. Kunz ABSTRACT Primate fruit choice among plant species has been attributed to different morphological plant and fruit characteristics. Despite a high abundance of animal-dispersed plant species in the savanna,forest mosaic of West Africa, few data are available on the interplay between morphological fruit traits and primate fruit consumers in this ecosystem. We tested whether olive baboons (Papio anubis) at Comoé National Park, north-eastern Ivory Coast, prefer fruit species with particular characteristics relative to the availability of these traits among the woody plant species at the study site. Specifically we were interested in the suites of traits that best predict fruit choice and seed handling by baboons. The baboons ate fruit/seeds from 74 identified plant species, representing 25 percent of the regional pool of woody plant species. They preferred trees to shrubs and lianas as fruit sources. Otherwise, baboons seemed to consume whatever fruit type, color, and size of fruit and seeds available, though they especially included larger fruit into their diet. Against expectations from the African bird,monkey fruit syndrome of brightly colored drupes and berries, baboons ate mostly species having large, dull-colored fruit. Fruit type and color best described whether baboons included a species into their diet, whereas fruit type and seed size best predicted whether baboons predated upon the seeds of their food plant species. As most plant species at the study site had medium-sized to large fruits and seeds, large frugivores like baboons might be particularly important for plant fitness and plant community dynamics in West African savanna,forest ecosystems. Abstract in French is available at http://www.blackwell-synergy.com/loi/btp [source] | ||||||||||||||||||||||