共查询到20条相似文献，搜索用时 15 毫秒
1.
Kathrin A. Otte Isabella Schrank Thomas Fröhlich Georg J. Arnold Christian Laforsch 《Molecular ecology》2015,24(15):3901-3917
Phenotypic plasticity, the ability of one genotype to express different phenotypes in response to changing environmental conditions, is one of the most common phenomena characterizing the living world and is not only relevant for the ecology but also for the evolution of species. Daphnia, the water flea, is a textbook example for predator‐induced phenotypic plastic defences; however, the analysis of molecular mechanisms underlying these inducible defences is still in its early stages. We exposed Daphnia magna to chemical cues of the predator Triops cancriformis to identify key processes underlying plastic defensive trait formation. To get a more comprehensive idea of this phenomenon, we studied four genotypes with five biological replicates each, originating from habitats characterized by different predator composition, ranging from predator‐free habitats to habitats containing T. cancriformis. We analysed the morphologies as well as proteomes of predator‐exposed and control animals. Three genotypes showed morphological changes when the predator was present. Using a high‐throughput proteomics approach, we found 294 proteins which were significantly altered in their abundance after predator exposure in a general or genotype‐dependent manner. Proteins connected to genotype‐dependent responses were related to the cuticle, protein synthesis and calcium binding, whereas the yolk protein vitellogenin increased in abundance in all genotypes, indicating their involvement in a more general response. Furthermore, genotype‐dependent responses at the proteome level were most distinct for the only genotype that shares its habitat with Triops. Altogether, our study provides new insights concerning genotype‐dependent and general molecular processes involved in predator‐induced phenotypic plasticity in D. magna. 相似文献
2.
Intraspecific variation is central to our understanding of evolution and population ecology, yet its consequences for community ecology are poorly understood. Animal personality – consistent individual differences in suites of behaviours – may be particularly important for trophic dynamics, where predator personality can determine activity rates and patterns of attack. We used mesocosms with aquatic food webs in which the top predator (dragonfly nymphs) varied in activity and subsequent attack rates on zooplankton, and tested the effects of predator personality. We found support for four hypotheses: (1) active predators disproportionately reduce the abundance of prey, (2) active predators select for predator‐resistant prey species, (3) active predators strengthen trophic cascades (increase phytoplankton abundance) and (4) active predators are more likely to cannibalise one another, weakening all other trends when at high densities. These results suggest that intraspecific variation in predator personality is an important determinant of prey abundance, community composition and trophic cascades. 相似文献
3.
Several studies have emphasized that inbreeding depression (ID) is enhanced under stressful conditions. Additionally, one might imagine a loss of adaptively plastic responses which may further contribute to a reduction in fitness under environmental stress. Here, we quantified ID in inbred families of the cyclical parthenogen Daphnia magna in the absence and presence of fish predation risk. We test whether predator stress affects the degree of ID and if inbred families have a reduced capacity to respond to predator stress by adaptive phenotypic plasticity. We obtained two inbred families through clonal selfing within clones isolated from a fish pond. After mild purging under standardized conditions, we compared life history traits and adaptive plasticity between inbred and outbred lineages (directly hatched from the natural dormant egg bank of the same pond). Initial purging of lineages under standardized conditions differed among inbred families and exceeded that in outbreds. The least purged inbred family exhibited strong ID for most life history traits. Predator‐induced stress hardly affected the severity of ID, but the degree to which the capacity for adaptive phenotypic plasticity was retained varied strongly among the inbred families. The least purged family overall lacked the capacity for adaptive phenotypic plasticity, whereas the family that suffered only mild purging exhibited a potential for adaptive plasticity that was comparable to the outbred population. We thus found that inbred offspring may retain the capacity to respond to the presence of fish by adaptive phenotypic plasticity, but this strongly depends on the parental clone engaging in selfing. 相似文献
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Qide Jin;Yeping Wang;Kun Zhang;Guoqing Li;Yanan Chen;Yujuan Hong;Hanxue Cheng;Daogui Deng; 《Ecology and evolution》2024,14(6):e11422
Daphnia can avoid predation by sensing fish kairomones and producing inducible defenses by altering the phenotype. In this study, the results showed that the morphological and life-history strategies of two Daphnia species (Daphnia pulex and Daphnia sinensis) exposed to Aristichthys nobilis kairomones. In the presence of fish kairomones, the two Daphnia species exhibited significantly smaller body length at maturity, smaller body length of offspring at the 10th instar, and longer relative tail spine of offspring. Nevertheless, other morphological and life-history traits of the two Daphnia species differed. D. pulex showed a significantly longer relative tail spine length and earlier age at maturity after exposure to fish kairomones. The total offspring number of D. sinensis exposed to fish kairomones was significantly higher than that of the control group, whereas that of D. pulex was significantly lower. These results suggest that the two Daphnia species have different inducible defense strategies (e.g., morphological and life-history traits) during prolonged exposure to A. nobilis kairomones, and their offspring also develop morphological defenses to avoid predation. It will provide reference for further exploring the adaptive evolution of Daphnia morphology and life-history traits in the presence of planktivorous fish. 相似文献
6.
Pathogen infection is typically costly to hosts, resulting in reduced fitness. However, pathogen exposure may also come at a cost even if the host does not become infected. These fitness reductions, referred to as “resistance costs”, are inducible physiological costs expressed as a result of a trade‐off between resistance to a pathogen and aspects of host fitness (e.g., reproduction). Here, we examine resistance and infection costs of a generalist fungal pathogen (Metschnikowia bicuspidata) capable of infecting a number of host species. Costs were quantified as reductions in host lifespan, total reproduction, and mean clutch size as a function of pathogen exposure (resistance cost) or infection (infection cost). We provide empirical support for infection costs and modest support for resistance costs for five Daphnia host species. Specifically, only one host species examined incurred a significant cost of resistance. This species was the least susceptible to infection, suggesting the possibility that host susceptibility to infection is associated with the detectability and size of resistance cost. Host age at the time of pathogen exposure did not influence the magnitude of resistance or infection cost. Lastly, resistant hosts had fitness values intermediate between unexposed control hosts and infected hosts. Although not statistically significant, this could suggest that pathogen exposure does come at some marginal cost. Taken together, our findings suggest that infection is costly, resistance costs may simply be difficult to detect, and the magnitude of resistance cost may vary among host species as a result of host life history or susceptibility. 相似文献
7.
Mougi A Kishida O Iwasa Y 《Evolution; international journal of organic evolution》2011,65(4):1079-1087
Inducible defenses of prey and inducible offenses of predators are drastic phenotypic changes activated by the interaction between a prey and predator. Inducible defenses occur in many taxa and occur more frequently than inducible offenses. Recent empirical studies have reported reciprocal phenotypic changes in both predator and prey. Here, we model the coevolution of inducible plasticity in both prey and predator, and examine how the evolutionary dynamics of inducible plasticity affect the population dynamics of a predator-prey system. Under a broad range of parameter values, the proportion of predators with an offensive phenotype is smaller than the proportion of prey with a defensive phenotype, and the offense level is relatively lower than the defense level at evolutionary end points. Our model also predicts that inducible plasticity evolves in both species when predation success depends sensitively on the difference in the inducible trait value between the two species. Reciprocal phenotypic plasticity may be widespread in nature but may have been overlooked by field studies because offensive phenotypes are rare and inconspicuous. 相似文献
8.
Phenotypic integration can be defined as the network of multivariate relationships among behavioural, physiological and morphological traits that describe the organism. Phenotypic integration plasticity refers to the change in patterns of phenotypic integration across environments or ontogeny. Because studies of phenotypic plasticity have predominantly focussed on single traits, a G × E interaction is typically perceived as differences in the magnitude of trait expression across two or more environments. However, many plastic responses involve coordinated responses in multiple traits, raising the possibility that relative differences in trait expression in different environments are an important, but often overlooked, source of G × E interaction. Here, we use phenotypic change vectors to statistically compare the multivariate life‐history plasticity of six Daphnia magna clones collected from four disparate European populations. Differences in the magnitude of plastic responses were statistically distinguishable for two of the six clones studied. However, differences in phenotypic integration plasticity were statistically distinguishable for all six of the clones studied, suggesting that phenotypic integration plasticity is an important component of G × E interactions that may be missed unless appropriate multivariate analyses are used. 相似文献
9.
The capacity of restored plant populations to adapt to new environmental challenges depends on within‐population genetic variation. We examined how much genetic and environmentally based variation for fitness‐associated traits exists within populations of two native grasses commonly used for restoration in California. We were also interested in understanding how phenotypic expression of genetic variation for these traits varies with growth environment. Thirty maternal families of Elymus glaucus (Blue wild rye) and Nassella pulchra (Purple needlegrass) were sampled from both coastal and interior populations and reciprocally transplanted into three replicated common gardens with and without interspecific competition at each site. Reproductive output of families differed both among years and with competition treatments. Phenotypic expression of genetic variation in culm production differed among populations and was very low when families were grown with interspecific competition. Without interspecific competition, the degree of genetic determination peaked in year two in both species (8.4 and 15.1% in E. glaucus and N. pulchra, respectively). Significant genetic differences in reproduction and phenotypic plasticity were found among N. pulchra subpopulations sampled less than 3 km apart, further highlighting the importance of thoroughly sampling available genetic variation in populations used for restoration. The variable and generally low expression of genetic variation indicates that rates of adaptation in restored populations of these native grasses may vary temporally and may be especially slow within competitive environments. 相似文献
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Comparisons of related species that have diverse spatial distributions provide an efficient way to investigate adaptive evolution in face of increasing global warming. The oyster subjected to high environmental selections is a model species as sessile marine invertebrate. This study aimed to detect the adaptive divergence of energy metabolism in two oyster subspecies from the genus Crassostrea—C. gigas gigas and C. gigas angulata—which are broadly distributed along the northern and southern coasts of China, respectively. We examined the effects of acute thermal stress on energy metabolism in two oyster subspecies after being common gardened for one generation in identical conditions. Thermal responses were assessed by incorporating physiological, molecular, and genomic approaches. Southern oysters exhibited higher fluctuations in metabolic rate, activities of key energetic enzymes, and levels of thermally induced gene expression than northern oysters. For genes involved in energy metabolism, the former displayed higher basal levels of gene expression and a more pronounced downregulation of thermally induced expression, while the later exhibited lower basal levels and a less pronounced downregulation of gene expression. Contrary expression pattern was observed in oxidative stress gene. Besides, energy metabolic tradeoffs were detected in both subspecies. Furthermore, the genetic divergence of a nonsynonymous SNP (SOD‐132) and five synonymous SNPs in other genes was identified and validated in these two subspecies, which possibly affects downstream functions and explains the aforementioned phenotypic variations. Our study demonstrates that differentiations in energy metabolism underlie the plasticity of adaptive divergence in two oyster subspecies and suggest C. gigas angulata with moderate phenotypic plasticity has higher adaptive potential to cope with exacerbated global warming. 相似文献
12.
- Functional traits are measurable characteristics of an organism that have an impact on its fitness. Variation in functional traits between and among species has been suggested to represent the basis for competition and selection, thus allowing for evolution in natural populations.
- In freshwater ecosystems, the availability of essential polyunsaturated fatty acids (PUFAs), in particular ω3‐ and ω6‐PUFAs, determines the food quality of phytoplankton for the herbivorous zooplankton Daphnia, an unselective filter feeder. The content of such essential PUFAs in the phytoplankton is thus a functional phytoplankton trait affecting the trophic transfer efficiency and dynamics at the pelagic plant–herbivore interface.
- In turn, the susceptibility of consumers to become limited by the availability of essential PUFAs is a fitness‐determining trait of Daphnia genotypes, and variability of this herbivore trait may thus affect the daphnids’ intrapopulation competition. To estimate the intrapopulation variation in susceptibility, we isolated clonal lines of Daphnia longispina from a natural population and compared the strength of their limitation by dietary PUFA availability via standardised laboratory growth assays. We used a liposome supplementation technique to enrich a PUFA‐poor green alga with essential ω3‐ and ω6‐PUFAs and determined juvenile somatic growth rate of different D. longispina genotypes as a fitness proxy.
- As expected, D. longispina genotypes that coexisted in a natural population differed markedly in their specific patterns of susceptibility to dietary PUFA availability. On average, the D. longispina population was more strongly susceptible to limitations in the availability of the ω6‐PUFA arachidonic acid (20:4ω6) than to limitations in the availability of ω3‐PUFAs α‐linolenic acid (18:3ω3) and eicosapentaenoic acid (20:5ω3).
- The ability to cope with PUFA limitation is thus a crucial trait that can probably affect intraspecific competition and Daphnia population structure. Therefore, we suggest that such intrapopulation variation in susceptibility to absence of dietary PUFAs might be one of the driving forces of natural selection and local adaptation among freshwater zooplankton.
13.
J. Colicchio 《Journal of evolutionary biology》2017,30(4):664-680
Trichomes, or leaf hairs, are epidermal extensions that take a variety of forms and perform many functions in plants, including herbivore defence. In this study, I document genetically determined variation, within‐generation plasticity, and a direct role of trichomes in herbivore defence for Mimulus guttatus. After establishing the relationship between trichomes and herbivory, I test for transgenerational effects of wounding on trichome density and herbivore resistance. Patterns of interannual variation in herbivore density and the high cost of plant defence makes plant–herbivore interactions a system in which transgenerational phenotypic plasticity (TPP) is apt to evolve. Here, I demonstrate that parental damage alters offspring trichome density and herbivore resistance in nature. Moreover, this response varies between populations. This is among the first studies to demonstrate that TPP contributes to variation in nature, and also suggests that selection can modify TPP in response to local conditions. 相似文献
14.
Induced response to herbivory in stinging hair traits of Japanese nettle (Urtica thunbergiana) seedlings in two subpopulations with different browsing pressures by sika deer 
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下载免费PDF全文 Evolutionary theories predict that natural selection favors inducible defense when the risk of predation is unpredictable. In this context, the magnitude of the induced defense in populations experiencing intermittent herbivory is predicted to be larger than that in populations experiencing constant herbivory when there is genetic differentiation between populations. To test this prediction, we conducted a clipping experiment to investigate induced response to shoot damage by the stinging hair traits of Japanese nettle (Urtica thunbergiana) seedlings. For this purpose, we studied two nettle subpopulations, one under constant browsing and another under intermittent browsing by sika deer in Nara Park, central Japan. The clipping experiment demonstrates that both subpopulations exhibited induced defenses in response to the clipping of the shoot apex as the number and length of stinging hairs increased after clipping. The subpopulation experiencing intermittent browsing exhibited smaller trait values and larger induced defenses, indicated by the number of stinging hairs on the upper leaf surface and the length of stinging hairs on both leaf surfaces compared with the subpopulation experiencing constant browsing. These results are consistent with the prediction and suggest that genetic differentiation of the induced defense between subpopulations is caused by adaptation to the herbivory regime. We discuss other plausible factors affecting the magnitude of the induced defense of the nettle subpopulations. 相似文献
15.
Cristóbal F. Gallegos Sánchez Jessica Beltrán Verónica Flores Alejandra V. González Bernabé Santelices 《Ecology and evolution》2018,8(11):5741-5751
Heterozygosity has been positively associated with fitness and population survival. However, the relationship between heterozygosity and adaptive phenotypic plasticity (i.e., plasticity which results in fitness homeostasis or improvement in changing environments) is unclear and has been poorly explored in seaweeds. In this study, we explored this relationship in the clonal red seaweed, Gracilaria chilensis by conducting three growth rate plasticity experiments under contrasting salinity conditions and by measuring heterozygosity with five microsatellite DNA markers. Firstly, we compared growth rate plasticity between the haploid and diploid phases. Secondly, we compared growth rate plasticity between diploids with different numbers of heterozygous loci. Finally, we compared growth rate plasticity between diploid plants from two populations that are expected to exhibit significant differences in heterozygosity. We found that, (i) diploids displayed a higher growth rate and lower growth rate plasticity than haploids, (ii) diploids with a higher number of heterozygous loci displayed lower growth rate plasticity than those exhibiting less heterozygosity, and (iii) diploid sporophytes from the population with higher heterozygosity displayed lower growth rate plasticity than those with lower heterozygosity. Accordingly, this study suggests that heterozygosity is inversely related to growth rate plasticity in G. chilensis. However, better genetic tools in seaweeds are required for a more definitive conclusion on the relationship between heterozygosity and phenotypic plasticity. 相似文献
16.
Of particular value in understanding the evolution of genotypes with broad phenotypic ranges (phenotypic plasticity) are the few examples of organisms with adaptive plasticity, such as those that develop a defensive morphology in response to cues from predators. We know little about the heritability of inducible defensive characters or the range of phenotypes available for selection to act on in the field. Membranipora membranacea is a colonial marine bryozoan that produces spines within two days of exposure to waterborne predator extracts. Surveys done in 1993 and 1995 showed that the population at Friday Harbor Labs, Washington, was polymorphic for inducible spine type and was composed of a constitutively spined type that produced spines in the absence of a predator stimulus, an unspined phenotype that did not produce spines irrespective of a stimulus, and an inducibly spined phenotype that would produce spines if exposed to the appropriate cue. In 1995, the frequencies of these types were determined through a laboratory common-garden experiment; 178 colonies were cultured from metamorphosis through approximately 30 days and then exposed to the cue. The inducible type was the dominant, comprising 80.3% of the population. The constitutive type made up 6.2% of the population, and the remaining 13.4 % was the unspined type. The frequency of the three types was similar to a preliminary trial of the experiment run in 1993. Experiments also showed that the lengths of the spines of the inducible type varied continuously among genotypes. To assess causes of variation in the inducible spine response and its clonal heritability, 16 clones were subdivided and grown in a common environment and exposed to a single dosage of spine inducing substance (SIS). Spine length showed high clonal heritability. The range of colony responses from a single environment varied from relatively unresponsive to highly responsive colonies with a very low threshold of response. Norms of reaction were quantified for spine lengths of inducible genotypes originating from two field environments by testing them in a concentration series of SIS. Both spine length and spine type varied with concentration of inducer. Within a clone, colonies were more likely to produce membranous spines than corner spines at higher concentrations. At low concentrations, only straight spines were produced. This study showed that populations of M. membranacea at Friday Harbor are a mix of inducible, nonspined and constitutively spined individuals. Even the inducible individuals showed high heritable variation in the length of spine activated, suggesting that there is considerable scope for the evolution of this character. A norm-of-reaction experiment further showed that the type of spine produced, membranous or corner, varied with the concentration of the cue. Factors maintaining the polymorphism and the broad range of genotypes could include high costs of defending the spined types coupled with a shifting biotic regime. 相似文献
17.
Reproductive timing is a key life‐history trait that impacts the pool of available mates, the environment experienced during flowering, and the expression of other traits through genetic covariation. Selection on phenology, and its consequences on other life‐history traits, has considerable implications in the context of ongoing climate change and shifting growing seasons. To test this, we grew field‐collected seed from the wildflower Mimulus guttatus in a greenhouse to assess the standing genetic variation for flowering time and covariation with other traits. We then created full‐sib families through phenological assortative mating and grew offspring in three photoperiod treatments representing seasonal variation in daylength. We find substantial quantitative genetic variation for the onset of flowering time, which covaried with vegetative traits. The assortatively‐mated offspring varied in their critical photoperiod by over two hours, so that families differed in their probability of flowering across treatments Allocation to flowering and vegetative growth changed across the daylength treatments, with consistent direction and magnitude of covariation among flowering time and other traits. Our results suggest that future studies of flowering time evolution should consider the joint evolution of correlated traits and shifting seasonal selection to understand how environmental variation influences life histories. 相似文献
18.
- The future increase in the atmospheric CO2 concentration is likely to affect the growth and performance of submerged freshwater macrophytes because of higher concentrations of free CO2 in the water at air equilibrium. We measured the plastic responses to free CO2 and light for several traits of four invasive aquatic plants (Elodea canadensis, Egeria densa, Hydrilla verticillata and Ceratophyllum demersum) that use bicarbonate.
- The plants were grown in standard culture media at either high (HiC, c. 50 μmol L?1) or low concentrations of free CO2 (LowC, c. 19 μmol L?1) combined with high (HiL, c. 150 μmol m?2 s?1) or low (LowL, c. 21 μmol m?2 s?1) light intensity in a 2 × 2 factorial experiment. We compared the relative growth rate (RGR), several morphological traits, the photosynthetic response to light intensity and the bicarbonate uptake capacity of the four species. For every trait measured, we established plasticity indices for light and CO2 availability.
- Light intensity had a greater effect than CO2 concentration on all species. The RGR of all four species was higher at high light intensity, and photosynthetic light responses acclimated to low light with a lower light compensation point, and with higher concentrations of photosynthetic pigments and quantum yield. The bicarbonate uptake capacity was generally highest at the high light intensity and high concentrations of free CO2. Plasticity indices for light intensity were consistently higher than for CO2 availability in all four species.
- As the growth and photosynthesis of the four invasive bicarbonate users were only slightly affected by the CO2 availability in air‐equilibrated water, the future rise in atmospheric CO2 is unlikely to exacerbate their invasive behaviour and may even reduce their competitiveness against species unable to use bicarbonate, especially at limiting light.
19.
S. Schaack D. E. Allen L. C. Latta IV K. K. Morgan M. Lynch 《Journal of evolutionary biology》2013,26(2):451-456
Understanding the impact of spontaneous mutations on fitness has many theoretical and practical applications in biology. Although mutational effects on individual morphological or life‐history characters have been measured in several classic genetic model systems, there are few estimates of the rate of decline due to mutation for complex fitness traits. Here, we estimate the effects of mutation on competitive ability, an important complex fitness trait, in a model system for ecological and evolutionary genomics, Daphnia. Competition assays were performed to compare fitness between mutation‐accumulation (MA) lines and control lines from eight different genotypes from two populations of Daphnia pulicaria after 30 and 65 generations of mutation accumulation. Our results show a fitness decline among MA lines relative to controls as expected, but highlight the influence of genomic background on this effect. In addition, in some assays, MA lines outperform controls providing insight into the frequency of beneficial mutations. 相似文献
20.
- Heat and odour production can have profound effects on pollination in cycads. It is therefore expected that these traits would co‐vary geographically with pollinator assemblages. Such intraspecific variation, may lead to the evolution of pollination ecotypes, which can be an early stage of pollinator‐mediated speciation.
- We measured cone temperatures using miniature temperature data loggers and examined the composition of cone volatile odours using headspace sampling and analysis with gas chromatography‐mass spectrometry in four populations spanning the range of the African cycad Encephalartos ghellinckii. Pollinator assemblages were also investigated in three populations.
- Male and female cones were thermogenic at pollen shed and receptive stages, respectively, but patterns of thermogenesis did not vary among populations. Scent emissions from cones in populations in the Drakensberg Mountains were characterised by cis‐β‐ocimene, β‐myrcene and (3E)‐1,3‐octadiene, while camphene and α‐pinene were characteristic of scent emissions from cones in populations closer to the coast. These differences in volatile blends corresponded with differences in insect assemblages.
- These results confirm intraspecific variation in volatile emissions of E. ghellinckii and support the predictions that intraspecific variation in volatile emissions will be associated with shifts in pollinator assemblages. While further work needs to be done to test for local adaptation in this system, this preliminary evidence is consistent with the formation of pollination ecotypes in the E. ghellinckii species complex.