Effects Of Genotypic Diversity Research Articles

Direct and legacy effects of genotypic diversity on population performance of Hydrocotyle vulgaris

Genetic diversity can have important ecological consequences on population dynamics and ecosystem functions and processes. While the direct effect of genetic diversity on population performance has been widely documented, its soil legacy effect has received little attention. To assess both the direct and soil legacy effects of genetic diversity on population performance, we conducted a plant-soil feedback experiment with 12 genotypes of a clonal plant Hydrocotyle vulgaris. We first conditioned soils (conditioning phase) by growing populations of H. vulgaris consisting of 1, 2, 4 and 8 genotypes in the soils and then tested the soils (test phase) by growing populations consisting of all 12 genotypes in sterilized bulk soils inoculated with each of the conditioned soils at a volume ratio of 10%. At the end of the conditioning phase, both biomass and the number of ramets of the populations of H. vulgaris first decreased and then increased with increasing genotypic diversity, indicating a direct effect of genetic diversity on population performance. At the end of the test phase, both biomass and number of ramets were significantly higher when the populations were grown in the soils conditioned by the populations consisting of 1 and 2 genotypes than when they were grown in the soils conditioned by the populations consisting of 4 and 8 genotypes, suggesting a soil legacy effect. Therefore, genetic diversity can have both a direct and a soil legacy effect on population productivity and size of H. vulgaris. These results highlight the importance of intraspecific differences on population performance and suggest that soil legacy effects should also be considered to fully understand the role of genetic diversity.

Effect of genotypic richness, drought and mycorrhizal associations on productivity and functional traits of a dominant C4 grass

AbstractWhile the relationship between genetic diversity and plant productivity has been established for many species, it is unclear whether environmental conditions and biotic associations alter the nature of the relationship. To address this, we investigated the interactive effects of genotypic diversity, drought and mycorrhizal association on plant productivity and plant traits. Our mesocosm study was set up at the Konza Prairie Biological Research Station, located in the south of Manhattan, Kansas. Andropogon gerardii, the focal species for our study, was planted in two levels of genotypic richness treatment: monoculture or three-genotype polyculture. A rainout shelter was constructed over half of the experimental area to impose a drought and Thiophanate-methyl fungicide was used to suppress arbuscular mycorrhizal fungi in selected pots within each genotypic richness and drought treatment. Genotypic richness and mycorrhizal association did not affect above-ground biomass of A. gerardii. Drought differentially affected the above-ground biomass, the number of flowers and bolts of A. gerardii genotypes, and the biomass and the functional traits also differed for monoculture versus polyculture. Our results suggest that drought and genotypic richness can have variable outcomes for different genotypes of a plant species.

Soil microbes drive the effect of plant species and genotypic diversity interaction on productivity.

PurposeThe effect of plant species and genotypic diversity on productivity has been well documented but little is known about the contribution of the interaction between species and genotypic diversity. Since the influence of soil microorganisms on the plant diversity-productivity relationship is increasingly recognized, we investigated potential interactions between plant species diversity, plant genotypic diversity and soil microbes. We hypothesized that the non-additive effects of plant species and genotypic diversity on productivity could be microbe-driven.MethodsWe set up pea and wheat monocultures and mixtures in a growth chamber, varying for their levels of genotypic diversity under three different soil microbial contexts. We assessed plant shoot and root biomass production, soil mineral nitrogen content and described the soil bacterial communities.ResultsWe found that shoot biomass in mixtures involving both species and genotypic diversity was higher than expected considering the additive effects of plant species diversity and genotypic diversity. Rather than a synergy between two positive effects of species and genotypic diversity, we observed that species mixture compensated the negative effect of genotypic diversity. Regarding microbial influence, we found that the effect of plant species diversity, plant genotypic diversity and their interaction on productivity were all driven by the soil microbial community as no effect was observed in a pre-sterilised soil.ConclusionOur study suggests that the plant diversity-productivity relationship could be shaped by a three-way interaction between plant species diversity, plant genotypic diversity and soil microbes. Thus, plant-microbe and plant-plant interactions could be a determinant of the plant diversity-productivity relationship.

​Effects of Genotypic Diversity on Insect-pests of Soybean

Background: Intercropping and mixed cropping based on two or more different crops have been widely used in Insect Pest Management to manage the population density of insect pests in various crops like maize with soybean, sorghum with soybean and sunflower with soybean. Genotypic diversity is the mixture or combination of various varieties/lines/genotypes of a crop. It decreases the insect-pests population by unfitness of crop to them due to intraspecific diversity such as mixture of susceptible and resistant varieties. Also, it increases the natural enemy population more due to longer period of flowering, availability of wide diverse food, more movement of herbivores etc. This concept has also been used successfully to manage insect-pests in maize, wheat and potato. In India, this connect is used in very small scale in crop. The objective of this study was to determine effects of genotypic diversity by comparing the population densities of major insect pests between monoculture of single variety and mixture of varieties. Methods: To test the effects of genotypic diversity on soybean insect-pest and their natural enemy population an experiment was laid in kharif 2018 and 2019 at the ICAR-Indian Institute of Soybean Research, Indore. All recommended agronomic package of practices were followed for raising of crop. Randomized block design with three replication having plot size of 9 rows of 5 meter row length was used. Totally 20 treatments were chosen for this experiment and out of 20 four treatments namely, T1, T6, T11 and T16 were the treatments of four varietal mixture treatments of almost similar maturity duration and agronomic traits and rest of treatments were of sole varietal treatments. Observations were made on insect-pests from 10 selected plants in each plot on three leaves selected at top, middle and lower portion of plant. Result: Effects of genotypic diversity in soybean revealed that for whitefly management T11 (NRC-86, JS-335, JS-2098 and RKS-45) was found most effective treatment. In case of mite, thrips and treehoppers management T1 (JS-9560, JS-20-34, MAUS-47 and MAUS-1460) was found most effective treatment. For leafhopper and mealy bug T6 (JS-9305, JS-2029, RVS-2001-4 and Dsb-28-3) was found most effective treatment. While for spittlebug T16 (NRC-37, JS-9752, RSC-1046 and RKS-113) was found most effective treatment. So, genotypic diverse treatments were found more effective than their respective sole varietal treatments.

基因型多样性对羊草种群年龄结构的影响

基因型多样性作为遗传多样性的重要组成部分，不仅在群落水平，而且在种群水平均可以发挥重要生态作用。以羊草（Leymus chinensis）为研究对象，设置5种基因型多样性梯度试验控制小区，进行基因型多样性对羊草种群年龄结构的影响研究。结果表明：随基因型多样性梯度的逐步增加，2a分蘖株生物量和数量均显著增加（P<0.05）；1-4龄级羊草根茎生物量、长度和干物质积累量多数呈极显著性增加的变化趋势（P<0.01）。在1、2、4、8和12种基因型多样性梯度时，分蘖株生物量及数量年龄结构均以1a或2a分蘖株所占比例为最高，年龄结构表现为增长型或稳定型；而羊草种群根茎生物量和长度也以2a根茎所占比例为最高，年龄结构表现为稳定型。随基因型多样性水平的增加，羊草种群分蘖株数量和生物量的年龄结构从增长型向稳定型过渡，但根茎长度和生物量的年龄结构均为稳定型。12基因型多样性水平的4龄级分蘖株和根茎的特征高于其他基因型多样性水平。因此，在不同基因型多样性水平羊草种群分蘖株和根茎具有增长型或稳定型的年龄结构，适当的基因型多样性数量显著促进了各龄级羊草分蘖株和根茎的生物量和数量特征的升高，但高度的基因型多样性水平会增加羊草种群中高龄级的分蘖株和根茎所占的比例，种群发展表现出衰退信号。;Genotypic diversity is an important part of biodiversity, which plays an important ecological role not only at the community level, but also at the population level. In this study, we set up five gradients of genotypic diversity to explore the effects of genotypic diversity on Leymus chinensis population from the perspective of age structure. The results showed that the biomass and number of 2nd age class tillers of L. chinensis population increased significantly with the increase of genotypic diversity (P<0.05),and the biomass of rhizome,length and dry matter accumulation of L. chinensis in different ages increased significantly (P<0.01). At five gradients of genotypic diversity,percentage of biomass and tiller number of 1st or 2nd age class tillers were the highest among different ages and showed expanding or stable age structure. But percentage of rhizome length and biomass in L. chinensis population of 2nd age rhizomes were highest proportion among different ages and showed stable age structure. With the increase of genotypic diversity,the age structure of tiller number and biomass of L. chinensis population transited from expanding type to stable type,but the age structure of rhizome length and biomass were stable type. The characteristics of tillers and rhizomes at age 4th of 12 genotypic diversity level were higher than other genotypes. The cumulative length of the rhizome of L. chinensis not only reflects the asexual reproduction ability, but also reflects its spatial expansion ability. High genotypic diversity significantly increases the length of the rhizome of L. chinensis population. The reason is that genotypic diversity can improve the soil nutrient absorption efficiency of L. chinensis, thus effectively promoting the root growth and providing conditions for population expansion. Therefore,the tillers and rhizomes of L. chinensis population have an expanding or stable age structure at different genotypic diversity levels. Moderate genotype number promotes the increase of the biomass and number characteristics of tillers and rhizomes at different age levels. This is due to the contribution of complementary effect to the positive effect of genotypic diversity. There are some differences in morphological and physiological characteristics among different genotypic levels of L. chinensis, resulting in different nutrient requirements and resource utilization ability of different genotype of L. chinensis. The increase of genotypic diversity can improve the utilization rate of resources and promote the development of L.chinensis population.However, over high genotypic diversity will increase the proportion of senior tillers and rhi senior zomes in the population of L. chinensis,and the development of population showed a decline signal.

Plant genotypic diversity effects on soil nematodes vary with trophic level

At local spatial scales, loss of genetic diversity within species can lead to species loss. Few studies, however, have examined plant genotypic diversity effects across trophic levels. We investigated genotypic diversity effects of Phragmites australis on belowground biomass and soil nematode communities. Our results revealed that belowground plant biomass and nematode abundance responses to plant genotypic diversity were uncoupled. Decreasing plant genotypic diversity decreased the abundance of lower, but not higher trophic level nematodes. Low plant genotypic diversity also decreased the structural footprint and functional indices of nematodes, indicating lowered metabolic functioning of higher trophic level nematodes and decreased soil food web stability. Our study suggests that plant genotypic diversity effects differ across trophic levels, taxonomic groups and ecosystem functions and that decreasing plant genotypic diversity could destabilise belowground food webs. This highlights the importance of conserving intraspecific plant diversity.

Better off alone? Compared performance of monoclonal and polyclonal stands of a cultivated red alga growth.

The objective of this study was to test, using a field experiment, the effect of genotypic diversity on productivity of farmed populations (Ancud and Chaica, Chile) of the domesticated red alga Agarophyton chilense (formerly known as Gracilaria chilensis), a species considered as economically important in Chile. Monoclonal and polyclonal (4 and 8 genotypes) subplots were outplanted into the mid intertidal in Metri Bay (Puerto Montt, Chile) during summer, a season in which A. chilense face higher temperatures (>18°C) and low nitrogen availability (<4.00 μmol). Ancud farm genotypes show higher growth rates in the monoclonal rather than the two polyclonal subplots. A similar tendency, yet not significant, was discernible in Chaica. In addition, whatever the population of origin of the thalli, no effect of genotypic diversity was detected neither on the agar yield and its quality, nor on the epiphyte load. Such unexpected results of a higher performance in plots with a lower genotypic diversity could be explained (a) by human‐assisted selection for dominant‐best‐performing genotypes that could counterbalance the negative effect caused by the low genotypic diversity in farms and (b) by the fact that the organisms inhabiting the algal mats do not impact the fitness of their host. Overall, the results obtained here suggest that despite farm induced selection lead to impoverished pools of genotypes, they may also have a positive effect of on the resistance of farmed populations to seasonal stressors. However, whether this may have a secondary negative effect on the longer term in a fluctuating environment remains to be determined, but may be avoided by adopting strategy of selection favoring different genotypes in space and time, as implemented in forestry.

Genotypic diversity mitigates negative effects of density on plant performance: a field experiment and life cycle analysis of common evening primrose Oenothera biennis

Summary Genotypic diversity in plant populations is known to enhance plant performance and ecosystem function. Nonetheless, the effect of genotypic diversity has rarely been examined across a population's lifecycle despite the expectation that changing conditions, such as population density, will alter the benefits of diversity. We simultaneously manipulated a component of genotypic diversity (richness, the number of genotypes) and density of common evening primrose Oenothera biennis to address the consequences for herbivory and lifetime fitness in a 2‐year field experiment that spanned seed germination to lifetime fruit production. We genotyped &gt;1100 seedlings with microsatellite DNA markers to determine realized diversity and density in plots sown with O. biennis seeds. Our design achieved quantitative variation in plant density and diversity, with one to 44 individuals established in field plots and two to eight genotypes per polyculture plot (based on microsatellite analysis of reproductive plants). We found a strong interaction between seed density and genetic diversity, with germination and establishment being 24% higher in genetic polycultures than monocultures, but only at low seed density. At high seed density, the opposite pattern emerged, with polycultures having 12% fewer individuals established than monocultures. Initial effects of emergence on plot density persisted through to the fruiting stage. Higher plant densities resulted in increased mortality, decreased probability of reproduction, decreased plant height and lower levels of lifetime fruit production per plant. Increasing genotypic diversity increased the probability of reproduction overall and showed a significant interaction with plant density mitigating the negative effects of high density on individual height and lifetime fruit production. Synthesis. Plant density and genotypic diversity interacted from the very early stages of seed germination and establishment of Oenothera biennis. This effect persisted over the 2‐year life cycle of plants, and genotypic diversity buffered against the negative fitness consequences of high plant density. These results imply a dynamic interplay between the long‐held paradigm of density effects in plant ecology and the genetic structure of populations.

不同邻居物种的基因型多样性对冷蒿生长的影响

不同邻居物种的基因型多样性对冷蒿生长的影响

Genetic diversity affects ecological performance and stress response of marine diatom populations.

Genetic diversity is considered an important factor, stabilizing ecological functions when organisms are faced with changing environmental conditions. Although well known from terrestrial systems, documentations of this relationship from marine organisms, and particularly planktonic microorganisms, are still limited. Here we experimentally tested the effects of genotypic diversity on ecologically relevant cellular parameters (growth, primary production, particulate organic carbon, particulate organic nitrogen, particulate organic phosphorus and biogenic silica) at optimal and suboptimal salinity conditions in a marine phytoplankton species. Multiple clonal genotyped and phenotypically characterized isolates of the diatom Skeletonema marinoi from the Baltic Sea were grown in monocultures and mixes of 5 and 20 clones at native (5 psu) and reduced (3 psu) salinities and respective parameters were compared. Re-genotyping of 30 individuals from each population at five microsatellite loci at the end of the experiment confirmed maintenance of genotypic richness. Although a diversity effect on growth was not detected, primary production and particulate organic nutrients were positively affected by increased diversity independent of salinity condition. Under salinity stress, highest values of primary production and particulate organic nitrogen content were measured at the high diversity level. The observed diversity effects emphasize the importance of genetic diversity of phytoplankton populations for ecological functions.

Genotypic diversity effects on biomass production in native perennial bioenergy cropping systems.

The perennial grass species that are being developed as biomass feedstock crops harbor extensive genotypic diversity, but the effects of this diversity on biomass production are not well understood. We investigated the effects of genotypic diversity in switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii) on perennial biomass cropping systems in two experiments conducted over 2008–2014 at a 5.4‐ha fertile field site in northeastern Illinois, USA. We varied levels of switchgrass and big bluestem genotypic diversity using various local and nonlocal cultivars – under low or high species diversity, with or without nitrogen inputs – and quantified establishment, biomass yield, and biomass composition. In one experiment (‘agronomic trial’), we compared three switchgrass cultivars in monoculture to a switchgrass cultivar mixture and three different species mixtures, with or without N fertilization. In another experiment (‘diversity gradient’), we varied diversity levels in switchgrass and big bluestem (1, 2, 4, or 6 cultivars per plot), with one or two species per plot. In both experiments, cultivar mixtures produced yields equivalent to or greater than the best cultivars. In the agronomic trial, the three switchgrass mixture showed the highest production overall, though not significantly different than best cultivar monoculture. In the diversity gradient, genotypic mixtures had one‐third higher biomass production than the average monoculture, and none of the monocultures were significantly higher yielding than the average mixture. Year‐to‐year variation in yields was lowest in the three‐cultivar switchgrass mixtures and Cave‐In‐Rock (the southern Illinois cultivar) and also reduced in the mixture of switchgrass and big bluestem relative to the species monocultures. The effects of genotypic diversity on biomass composition were modest relative to the differences among species and genotypes. Our findings suggest that local genotypes can be included in biomass cropping systems without compromising yields and that genotypic mixtures could help provide high, stable yields of high‐quality biomass feedstocks.

Effects of tree species diversity and genotypic diversity on leafminers and parasitoids in a tropical forest plantation

The effects of tree diversity on herbivore-enemy interactions have received relatively little attention and even fewer studies have compared the relative influence of tree intra- versus interspecific diversity on such dynamics. 2 We evaluated the effects of mahogany ( Swietenia macrophylla) genotypic diversity and tree species diversity on parasitoid attack and species richness associated with Phyllocnistis meliacella, a specialist herbivore on mahogany, in a forest diversity experiment consisting of 74 plots (21 × 21 m 2 ; 64 plants/plot). We sampled 34 of such plots classified as: mahogany monocultures of one maternal family (i.e. genotype), mahogany monocultures of four families and polycultures of four species (including mahogany). We surveyed leafminer abundance and collected mined leaves to estimate parasitism and parasitoid species richness. 3 Leafminer abundance was not influenced by either type of diversity. Similarly, there were no effects of genotypic diversity or species diversity on parasitism or parasitoid species richness. Plant diversity effects on parasitoids were probably absent because the species attackingP. meliacella are dietary generalists that likely recruited to multiple host species (in addition to P. meliacella) and their responses to diversity could have cancelled each other out. 4 Future work should explicitly investigate how predator and parasitoid traits mediate the effects of plant diversity on tritrophic interactions.

Effects of pepper (Capsicum chinense) genotypic diversity on insect herbivores

AbstractThere is growing interest on the effects of plant genotypic diversity on higher trophic levels. The present study investigated whether genotypic diversity in Capsicum chinense peppers influenced attack by leaf‐mining fly larvae (Lyriomyza trifolii) and fruit‐eating weevils (Anthonomus eugenii), as well as parasitoid attack associated with weevils. We established genotypic monocultures (n = 10, two plots/each of five inbred lines) and polycultures (n = 5, random mixtures of three out of the five lines) and conducted weekly surveys of fruit number, leafmines and weevil fruit attack over a 5‐month period. In addition, we collected fruits to rear weevils and estimated parasitism associated with this herbivore. There was a tendency for a negative effect of diversity on leafminer attack, with polycultures exhibiting a 24% reduction in leafminer attack relative to monocultures. By contrast, diversity did not influence weevil fruit attack or the level of parasitism associated with the weevil. Our findings show that plant genotypic diversity effects vary among herbivore species, presumably as a result of differences in herbivore traits (e.g. diet breadth, mobility). We also emphasize that manipulating plant genotypic diversity can be an important consideration for pest management in this commercially important crop.

Comparison of tree genotypic diversity and species diversity effects on different guilds of insect herbivores

Although the effects of plant diversity on herbivores are contingent upon herbivore traits and the source of plant diversity (e.g. intra‐ and interspecific), most studies have analyzed these effects separately. We compared the effects of genotypic diversity of big‐leaf mahogany Swietenia macrophylla with that of tree species diversity on two specialist caterpillars (Hypsipyla grandella stem borers and Phyllocnistis meliacella leaf miners) and three generalist leafhoppers (Cicadellidae) feeding on mahogany in a large‐scale (7.2 ha) forest diversity experiment in southern Mexico. The experiment consisted of fifty‐nine 21 × 21‐m plots, with 64 tree saplings each (3‐m spacing between plants). Plots were either mahogany monocultures or species polycultures of four species (including mahogany) and – within each of these two plot types – mahogany was represented by either one or four genotypes. Throughout a five‐month period, beginning six months after planting, we measured mahogany growth and monitored herbivore and predator (spider) abundance. We found no effect of mahogany genotypic diversity on either specialist caterpillars or generalist leafhoppers, and this result was consistent across levels of tree species diversity. In contrast, species diversity had significant effects on both specialists but neither of the generalist herbivores. Specifically, species diversity lowered H. grandella attack at the middle of the sampling season, but increased attack at the end of the season, whereas P. meliacella abundance was consistently reduced. Such effects were not mediated by effects of species diversity on plant growth (of which there were none), but rather through resource heterogeneity. Diversity did not influence spider abundance. This study is one of few to directly compare sources of plant diversity, and uniquely compares such effects among herbivores with contrasting life histories (e.g. diet breadths). Overall, we demonstrate that plant species diversity effects outweigh those of genotypes, and our results suggest that such effects are stronger on specialist than generalist herbivores.

羊草基因型多样性能增强种群对干扰的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 羊草基因型多样性能增强种群对干扰的响应 DOI: 10.5846/stxb201405130979 作者: 作者单位: 南开大学生命科学学院,南开大学生命科学学院,南开大学生命科学学院,南开大学生命科学学院,南开大学生命科学学院,南开大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31270463,30800132) Leymus chinensis genotypic diversity increases the response of populations to disturbance Author: Affiliation: College of Life Science,NanKai University,College of Life Science,NanKai University,College of Life Science,NanKai University,College of Life Science,NanKai University,College of Life Science,NanKai University,College of Life Science,NanKai University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究了不同基因型多样性(1、3、6 三种基因型组合)羊草种群的地上生物量、地下生物量、分蘖数、根茎芽数和根冠比5个指标对干扰强度(用不同留茬高度来模拟)的响应。结果表明:(1) 基因型多样性和干扰强度对地上生物量、地下生物量、分蘖数和根茎芽数均有显著影响(P < 0.05),但两者的交互作用不显著(P > 0.05)。其中,多基因型组合(3、6 基因型组合)羊草种群中这4个响应变量的值均显著高于单基因型羊草种群(P < 0.05);而干扰强度的增加显著降低了这4个响应变量的值(P < 0.05)。对于根冠比这一响应变量来说,仅干扰强度对其产生了显著地影响(P < 0.05)。(2) 29个基因型多样性效应值中,有25个值大于0,其中12个表现为显著的基因型多样性正效应。依 Loreau 和 Hector 的方法将多样性净效应分解后发现,互补效应和选择效应共同主导12个响应指标的基因型多样性效应,而互补效应独自主导3个、选择效应独自主导5个响应指标的基因多样性效应;但对基因型多样性正效应起主要贡献的是互补效应。所得结果表明,基因型多样性能提高羊草种群的表现,能增强羊草种群对干扰的响应,不同基因型间的互补作用对这种正效应起主要贡献,这将为该物种种质资源保护和合理利用提供理论指导。 Abstract:The current rapid loss of biodiversity from the ecosystem to the species level at global regional and local scales is considered to be one of the major threats to the continued good functioning of ecosystems and the biosphere at large. Recent research has demonstrated that genotypic diversity within species also has important ecological impacts. Especially for dominant and constructive species, genotypic diversity within species may enhance plant population productivity and resistance to disturbance, reduce susceptibility to alien plant invasions, and affect associated arthropod community composition and diversity through several of mechanisms. The underlying mechanisms by which genotypic diversity within species may alter ecosystem processes are analogous to those proposed for species diversity. For both species diversity and genotypic diversity within species, the effects of diversity may be partitioned into "selection" and "complementarity" effects, where selection effect occurs if the community includes a genotype with a specific trait that becomes dominant over time. Complementarity effects occur when function increases or decreases as a result of interactions among conspecifics. Selection effects result in higher or lower functioning than expected, based on the average performance of the genotypes in monoculture, which is called non-transgressive over-yielding. Complementarity effects result in a diverse assemblage that performs better than its best performing member, which is called transgressive over-yielding. In northern China, typical steppe is one of the main steppe types. Leymus chinensis is the dominant and constructive species of the typical steppe, playing an important role in the community. Due to climate change and frequent human activities, the typical steppe has seriously degraded over half a century, but we found that L. chinensis in degraded steppe still plays an important role in maintaining the structure and functioning of typical steppe. Therefore, it is necessary to investigate how the genotypic diversity of L. chinensis affects the structure and functioning of an ecosystem. In this study, we examined the effects of L. chinensis genotypic diversity on the performance of the above- and below-ground biomass, number of tillers, number of rhizome buds, and root to shoot ratio in response to disturbance over four months. (1) The genotypic diversity and the intensity of disturbance had significant effects (P < 0.05) on the above- and below-ground biomass, number of tillers, and number of rhizome buds, but their interactions had no significant effects on these variables (P > 0.05). The values of these 4 response variables in polyculture (3, 6 genotypes) were significantly higher than those in monoculture (P < 0.05), and these response values decreased with increasing of disturbance. The intensity of disturbance had a significant effect (P < 0.05) on the performance of the root to shoot ratio, which was higher for the most serious disturbance condition (H5) compared to the other conditions. (2) The net diversity effects were positive for 25 out of 29 variables, and were significantly higher than 0 for 12 variables. After partitioning the net diversity effect by the Loreau & Hector method, the results showed that genotypic diversity effects were driven by both the complementarity and selection effects for 12 variables, by the complementarity effect for 3 variables, and by the selection effect for 5 variables;however, the complementarity effect contributed more to the positive diversity effect. These results indicated that genotypic diversity may improve the performance of L. chinensis by the complementarity effect, even under disturbance conditions, with this information being expected to contribute to the conservation and utilization of germplasm resources of this species. 参考文献 相似文献 引证文献

Additive and non‐additive effects of birch genotypic diversity on arthropod herbivory in a long‐term field experiment

Herbivores are important drivers of plant population dynamics and community composition in natural and managed systems. Intraspecific genetic diversity of long‐lived plants like trees might shape patterns of herbivory by different guilds of herbivores that trees experience through time. However, previous studies on plant genetic diversity effects on herbivores have been largely short‐term. We investigated how tree genotypic variation and diversity influence herbivory of silver birchBetula pendulain a long‐term field experiment. Using clones of eight genotypes, we constructed experimental plots consisting of one, two, four or eight genotypes, and measured damage by five guilds of arthropod herbivores twice a year over three different years (four, six and nine years after the experiment was established). Genotypes varied significantly for most types of herbivore damage, but genotype resistance rankings often shifted over time, and none of the clones was more resistant than all others to all types of herbivores. At the plot level, birch genotypic diversity had significant positive additive effect on leaf rollers and negative non‐additive effects on chewing herbivores and gall makers. In contrast, leaf‐mining and leaf‐tying damage was not influenced by birch genotypic diversity. Within diverse plots, the direction of genotypic diversity effects varied depending on birch genotype, some having lower and some having higher herbivory in mixed stands. This research highlights the importance of long‐term studies including different feeding guilds of herbivores to understand the effects of plant genetic diversity on arthropod communities. Different responses of various feeding guilds to genotypic diversity and shifts in resistance of individual genotypes over time indicate that genotypic mixtures are unlikely to result in overall reduction in herbivory over time.

Positive effects of plant genotypic and species diversity on anti-herbivore defenses in a tropical tree species.

Despite increasing evidence that plant intra- and inter-specific diversity increases primary productivity, and that such effect may in turn cascade up to influence herbivores, there is little information about plant diversity effects on plant anti-herbivore defenses, the relative importance of different sources of plant diversity, and the mechanisms for such effects. For example, increased plant growth at high diversity may lead to reduced investment in defenses via growth-defense trade-offs. Alternatively, positive effects of plant diversity on plant growth may lead to increased herbivore abundance which in turn leads to a greater investment in plant defenses. The magnitude of trait variation underlying diversity effects is usually greater among species than among genotypes within a given species, so plant species diversity effects on resource use by producers as well as on higher trophic levels should be stronger than genotypic diversity effects. Here we compared the relative importance of plant genotypic and species diversity on anti-herbivore defenses and whether such effects are mediated indirectly via diversity effects on plant growth and/or herbivore damage. To this end, we performed a large-scale field experiment where we manipulated genotypic diversity of big-leaf mahogany (Swietenia macrophylla) and tree species diversity, and measured effects on mahogany growth, damage by the stem-boring specialist caterpillar Hypsipyla grandella, and defensive traits (polyphenolics and condensed tannins in stem and leaves). We found that both forms of plant diversity had positive effects on stem (but not leaf) defenses. However, neither source of diversity influenced mahogany growth, and diversity effects on defenses were not mediated by either growth-defense trade-offs or changes in stem-borer damage. Although the mechanism(s) of diversity effects on plant defenses are yet to be determined, our study is one of the few to test for and show producer diversity effects on plant chemical defenses.

Effects of genotypic diversity of Phragmites australis on primary productivity and water quality in an experimental wetland

An increasing number of studies have shown that genetic diversity within plant species can influence important ecological processes. Here, we report a two-year wetland mesocosm experiment in which genotypic richness of Phragmites australis was manipulated to examine its effects on primary productivity and nitrogen removal from water. We used six genotypes of P. australis, and compared primary productivity and nitrogen concentration in the outflow water of the mesocosms between monocultures and polycultures of all six genotypes. We also quantified the abundance of denitrifying bacteria, as denitrification is a primary mechanism of nitrogen removal in addition to the biotic uptake by P. australis. Plant productivity was significantly greater in genotypic polycultures compared to what was expected based on monocultures. This richness effect on productivity was driven by both complementary and competitive interactions among genotypes. In addition, nitrogen removal rates of mesocosms were generally greater in genotypic polycultures compared to those expected based on monocultures. This effect, particularly pronounced in autumn, may largely be attributable to the enhanced uptake of nitrogen by P. australis, as the abundance of nitrite reducers did not increase with plant genotypic diversity. Although our effect sizes were relatively small compared to previous experiments, our study emphasizes the effect of genotypic interactions in regulating multiple ecological processes.

Bacterial Diversity Stabilizes Community Productivity

BackgroundStability is a crucial ecosystem feature gaining particular importance in face of increasing anthropogenic stressors. Biodiversity is considered to be a driving biotic force maintaining stability, and in this study we investigate how different indices of biodiversity affect the stability of communities in varied abiotic (composition of available resources) and biotic (invasion) contexts.Methodology/Principal FindingsWe set up microbial microcosms to study the effects of genotypic diversity on the reliability of community productivity, defined as the inverse of the coefficient of variation of across-treatment productivity, in different environmental contexts. We established a bacterial diversity gradient ranging from 1 to 8 Pseudomonas fluorescens genotypes and grew the communities in different resource environments or in the presence of model invasive species. Biodiversity significantly stabilized community productivity across treatments in both experiments. Path analyses revealed that different aspects of diversity determined stability: genotypic richness stabilized community productivity across resource environments, whereas functional diversity determined stability when subjected to invasion.Conclusions/SignificanceBiodiversity increases the stability of microbial communities against both biotic and abiotic environmental perturbations. Depending on stressor type, varying aspects of biodiversity contribute to the stability of ecosystem functions. The results suggest that both genetic and functional diversity need to be preserved to ensure buffering of communities against abiotic and biotic stresses.

Genotypic diversity enhances invasive ability of Spartina alterniflora

Although genetic diversity is very important for alien species, which have to cope with new environments, little is known about the role that genetic diversity plays in their invasive success. In this study, we set up a manipulation experiment including three levels of genotypic diversity to test whether genotypic diversity can enhance the invasive ability of alien species, in our case the invasive Spartina alterniflora in China, and to infer the underlying mechanisms. There was no significant relationship between genotypic diversity and parameters of performance in the first year; however, from the summer of the second year onwards, genotypic diversity enhanced four of the six parameters of performance. After two growing seasons, there were significant positive relationships between genotypic diversity and maximum spread distance, patch size, shoot number per patch, and aboveground biomass. Moreover, abundance of the native dominant species Scirpus mariqueter was marginally significantly decreased with genotypic diversity of S.alterniflora, suggesting that enhanced invasive ability of S.alterniflora may have depressed the growth of the native species. There was no significant difference in most measures of performance among six genotypes, but we observed a transgressive over performance in four measures in multiple-genotype patches. At the end of the experiment, there were significant nonadditive effects of genotypic diversity according to Monte Carlo permutations, in six-genotype, but not three-genotype plots. Our results indicated that both additive and nonadditive effects played roles in the positive relationship between genetic diversity and invasion success, and nonadditive effects were stronger as duration increased.