Partitioning plant genetic and environmental drivers of above and belowground community assembly

2017 ◽  
Author(s):  
Matthew Barbour ◽  
Sonya Erlandson ◽  
Kabir Peay ◽  
Brendan Locke ◽  
Erik S. Jules ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phenotypic Plasticity ◽  
Host Plant ◽  
Environmental Effects ◽  
Natural Variation ◽  
Plant Traits ◽  
Genetic Effects ◽  
Environmental Drivers ◽  
Leaf Quality ◽  
Wind Exposure

Host-plant genetic variation affects the diversity and composition of associated above and belowground communities. Most evidence supporting this view is derived from studies within a single common garden, thereby constraining the range of biotic and abiotic environmental conditions that might directly or indirectly (via phenotypic plasticity) affect communities. If natural variability in the environment renders host-plant genetic effects on associated communities unimportant, then studying the community-level consequences of genetic variation may not be warranted. We addressed this knowledge gap by planting a series of common gardens consisting of 10 different clones (genotypes) of the willow Salix hookeriana in a coastal dune ecosystem and manipulated natural variation in ant-aphid interactions (biotic) and wind exposure (abiotic) in two separate experiments. We then quantified the responses of associated species assemblages both above (foliar arthropods) and belowground (rhizosphere fungi and bacteria). In addition, we quantified plant phenotypic responses (plant growth, leaf quality, and root quality) to tease apart the effects of genetic variation, phenotypic plasticity, and direct environmental effects on associated communities. In the ant-aphid experiment, we found that willow genotype explained more variation in foliar arthropod communities than aphid additions and proximity to aphid-tending ant mounds. However, aphid additions modified willow genetic effects on arthropod community composition by attracting other aphid species to certain willow genotypes. In the wind experiment, wind exposure explained more variation than willow genotype in structuring communities of foliar arthropods and rhizosphere bacteria. Still, willow genotype had strong effect sizes on several community properties of arthropods and fungi, indicating that host-plant genetic variation remains important. Across both experiments, genetic variation in plant traits was more important than phenotypic plasticity in structuring associated communities. The relative importance of genetic variation vs. direct environmental effects though depended on the type of environmental gradient (G > E-aphid, but E-wind > G). Taken together, our results suggest that host-plant genetic variation is an important driver of above and belowground biodiversity, despite natural variation in the biotic and abiotic environment.

scholarly journals The choice of the environmental covariate affects the power to detect variation in reaction norm slopes

2018 ◽  
Author(s):  
Phillip Gienapp
Keyword(s):  
Genetic Variation ◽  
Phenotypic Plasticity ◽  
Environmental Effects ◽  
Reaction Norm ◽  
Environmental Variable ◽  
Negative Results ◽  
Environmental Driver ◽  
The Mean ◽  
Evolutionary Consequences ◽  
Biased Estimates

AbstractMany traits are phenotypically plastic, i.e. the same genotype expresses different phenotypes depending on the environment. Individuals and genotypes can vary in this response to the environment and this individual (IxE) and genetic variation in reaction norm slopes (GxE) can have important ecological or evolutionary consequences. Studies on variation in plasticity often fail to show IxE or GxE; this can indicate a genuine absence or simply a lack of power. There is, however, another factor that could potentially affect the power to detect IxE or GxE: the choice of the environmental variable included in the analysis. Identifying the genuine environmental driver of phenotypic plasticity will mostly be impossible and hence only a proxy is included in the analysis. However, if this proxy is too weakly correlated with the real driver of plasticity, this will bias IxE and GxE downwards, could lead to spurious negative results and invalid conclusions. As the mean phenotype in a given environment captures all environmental effects on the phenotype, using it as ‘environment’ in the analysis should increase the power to detect IxE or GxE. Using simulations I here showed that using weakly correlated proxies indeed biased estimates downwards but that when using the environment-specific means this was not the case. Using environment-specific means as a covariate has been commonly used in animal and plant breeding but rarely used outside these fields despite its potential usefulness as ‘yardstick’ to test whether IxE or GxE is present or absent in the phenotype of interest.

Phenotypic plasticity of plant traits contributing to grain and biomass yield of dual-purpose sorghum

Planta ◽  
2021 ◽  
Vol 253 (4) ◽  
Author(s):  
Malick Ndiaye ◽  
Bertrand Muller ◽  
Komla Kyky Ganyo ◽  
Aliou Guissé ◽  
Ndiaga Cissé ◽  
...  
Keyword(s):  
Phenotypic Plasticity ◽  
Biomass Yield ◽  
Plant Traits ◽  
Dual Purpose

scholarly journals The expression of additive and nonadditive genetic variation under stress.

Genetics ◽  
1995 ◽  
Vol 140 (3) ◽  
pp. 1149-1159
Author(s):  
M W Blows ◽  
M B Sokolowski
Keyword(s):  
Genetic Variation ◽  
Development Time ◽  
Genetic Effects ◽  
Hybrid Breakdown ◽  
Bristle Number ◽  
Gene Complexes ◽  
General Expectation ◽  
Faster Development ◽  
Seven Generations ◽  
Additive Genetic Effects

Abstract Experimental lines of Drosophila melanogaster derived from a natural population, which had been isolated in the laboratory for approximately 70 generations, were crossed to determine if the expression of additive, dominance and epistatic genetic variation in development time and viability was associated with the environment. No association was found between the level of additive genetic effects and environmental value for either trait, but nonadditive genetic effects increased at both extremes of the environmental range for development time. The expression of high levels of dominance and epistatic genetic variation at environmental extremes may be a general expectation for some traits. The disruption of the epistatic gene complexes in the parental lines resulted in hybrid breakdown toward faster development and there was some indication of hybrid breakdown toward higher viability. A combination of genetic drift and natural selection had therefore resulted in different epistatic gene complexes being selected after approximately 70 generations from a common genetic base. After crossing, the hybrid populations were observed for 10 generations. Epistasis contributed on average 12 hr in development time. Fluctuating asymmetry in sternopleural bristle number also evolved in the hybrid populations, decreasing by > 18% in the first seven generations after hybridization.

scholarly journals Evaluating indirect genetic effects of siblings using singletons

2021 ◽  
Author(s):  
Laurence Howe ◽  
David Evans ◽  
Gibran Hemani ◽  
George Davey Smith ◽  
Neil Martin Davies
Keyword(s):  
Genetic Variation ◽  
Educational Attainment ◽  
Family Environment ◽  
Phenotypic Variation ◽  
Molecular Genetic ◽  
Genetic Effects ◽  
Polygenic Risk Score ◽  
Indirect Genetic Effects ◽  
Molecular Genetic Evidence ◽  
Older Siblings

Estimating effects of parental and sibling genotypes (indirect genetic effects) can provide insight into how the family environment influences phenotypic variation. There is growing molecular genetic evidence for effects of parental phenotypes on their offspring (e.g. parental educational attainment), but the extent to which siblings affect each other is currently unclear.Here we used data from samples of unrelated individuals, without (singletons) and with biological full-siblings (non-singletons), to investigate and estimate sibling effects. Indirect genetic effects of siblings increase (or decrease) the covariance between genetic variation and a phenotype. It follows that differences in genetic association estimates between singletons and non-singletons could indicate indirect genetic effects of siblings.We used UK Biobank data to estimate polygenic risk score (PRS) associations for height, BMI and educational attainment in singletons (N = 50,143) and non-singletons (N = 328,549). The educational attainment PRS association estimate was 12% larger (95% C.I. 3%, 21%) in the non-singleton sample than in the singleton sample, but the height and BMI PRS associations were consistent. Birth order data suggested that the difference in educational attainment PRS associations was driven by individuals with older siblings rather than firstborns. The relationship between number of siblings and educational attainment PRS associations was non-linear; PRS associations were 24% smaller in individuals with 6 or more siblings compared to the rest of the sample (95% C.I. 11%, 38%). We estimate that a 1 SD increase in sibling educational attainment PRS corresponds to a 0.025 year increase in the index individual’s years in schooling (95% C.I. 0.013, 0.036).Our results suggest that older siblings influence the educational attainment of younger siblings, adding to the growing evidence that effects of the environment on phenotypic variation partially reflect social effects of germline genetic variation in relatives.

scholarly journals Mhc polymorphisms fail to explain the heritability of phytohaemagglutinin-induced skin swelling in a wild passerine

2009 ◽  
Vol 5 (6) ◽  
pp. 784-787 ◽  
Author(s):  
Camille Bonneaud ◽  
Janet S. Sinsheimer ◽  
Murielle Richard ◽  
Olivier Chastel ◽  
Gabriele Sorci
Keyword(s):  
Genetic Variation ◽  
Immune Responses ◽  
Environmental Effects ◽  
Natural Populations ◽  
Wild Populations ◽  
Genetic Determinants ◽  
House Sparrows ◽  
Additive Genetic Variation ◽  
Significant Heritability ◽  
Mhc Polymorphisms

Genetic estimates of the variability of immune responses are rarely examined in natural populations because of confounding environmental effects. As a result, and because of the difficulty of pinpointing the genetic determinants of immunity, no study has to our knowledge examined the contribution of specific genes to the heritability of an immune response in wild populations. We cross-fostered nestling house sparrows to disrupt the association between genetic and environmental effects and determine the heritability of the response to a classic immunological test, the phytohaemagglutinin (PHA)-induced skin swelling. We detected significant heritability estimates of the response to PHA, of body mass and tarsus length when nestlings were 5 and 10 days old. Variation at Mhc genes, however, did not explain a significant portion of the genetic variation of nestling swelling to PHA. Our results suggest that while PHA-induced swelling is influenced by the nest of origin, the importance of additive genetic variation relative to non-additive genetic variation and the genetic factors that influence the former in wild populations still need to be identified for this trait.

scholarly journals High differentiation in functional traits but similar phenotypic plasticity in populations of a soil specialist along a climatic gradient

2020 ◽  
Vol 125 (6) ◽  
pp. 969-980 ◽  
Author(s):  
Silvia Matesanz ◽  
Marina Ramos-Muñoz ◽  
Mario Blanco-Sánchez ◽  
Adrián Escudero
Keyword(s):  
Genetic Variation ◽  
Phenotypic Plasticity ◽  
Functional Traits ◽  
Common Garden ◽  
Population Level ◽  
General Purpose ◽  
Climatic Conditions ◽  
Environment Interaction ◽  
Moisture Variation ◽  
Neutral Genetic Variation

Abstract Background and Aims Plants experiencing contrasting environmental conditions may accommodate such heterogeneity by expressing phenotypic plasticity, evolving local adaptation or a combination of both. We investigated patterns of genetic differentiation and plasticity in response to drought in populations of the gypsum specialist Lepidium subulatum. Methods We created an outdoor common garden with rain exclusion structures using 60 maternal progenies from four distinct populations that substantially differ in climatic conditions. We characterized fitness, life history and functional plasticity in response to two contrasting treatments that realistically reflect soil moisture variation in gypsum habitats. We also assessed neutral genetic variation and population structure using microsatellite markers. Key Results In response to water stress, plants from all populations flowered earlier, increased allocation to root tissues and advanced leaf senescence, consistent with a drought escape strategy. Remarkably, these probably adaptive responses were common to all populations, as shown by the lack of population × environment interaction for almost all functional traits. This generally common pattern of response was consistent with substantial neutral genetic variation and large differences in population trait means. However, such population-level trait variation was not related to climatic conditions at the sites of origin. Conclusions Our results show that, rather than ecotypes specialized to local climatic conditions, these populations are composed of highly plastic, general-purpose genotypes in relation to climatic heterogeneity. The strikingly similar patterns of plasticity among populations, despite substantial site of origin differences in climate, suggest past selection on a common norm of reaction due to similarly high levels of variation within sites. It is thus likely that plasticity will have a prevalent role in the response of this soil specialist to further environmental change.

scholarly journals Genetic specificity of a plant–insect food web: Implications for linking genetic variation to network complexity

2016 ◽  
Vol 113 (8) ◽  
pp. 2128-2133 ◽  
Author(s):  
Matthew A. Barbour ◽  
Miguel A. Fortuna ◽  
Jordi Bascompte ◽  
Joshua R. Nicholson ◽  
Riitta Julkunen-Tiitto ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Food Web ◽  
Host Plant ◽  
Trophic Interactions ◽  
Common Garden ◽  
Ecological Networks ◽  
Experimental Population ◽  
Trait Variation ◽  
Intraspecific Genetic Variation ◽  
Food Web Complexity

Theory predicts that intraspecific genetic variation can increase the complexity of an ecological network. To date, however, we are lacking empirical knowledge of the extent to which genetic variation determines the assembly of ecological networks, as well as how the gain or loss of genetic variation will affect network structure. To address this knowledge gap, we used a common garden experiment to quantify the extent to which heritable trait variation in a host plant determines the assembly of its associated insect food web (network of trophic interactions). We then used a resampling procedure to simulate the additive effects of genetic variation on overall food-web complexity. We found that trait variation among host-plant genotypes was associated with resistance to insect herbivores, which indirectly affected interactions between herbivores and their insect parasitoids. Direct and indirect genetic effects resulted in distinct compositions of trophic interactions associated with each host-plant genotype. Moreover, our simulations suggest that food-web complexity would increase by 20% over the range of genetic variation in the experimental population of host plants. Taken together, our results indicate that intraspecific genetic variation can play a key role in structuring ecological networks, which may in turn affect network persistence.

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