Genetic Variation For Traits Research Articles

Genes and environment: An old pair in a new era.

What is the relationship between our genes and the environment we live in with regard to health? Like the debate about nature or nurture in the determination of our personality and behavior, the issue of genes and environment has been discussed intensely in the last two centuries. Is it Darwin or Lamarck who is right about the basic determinants of our health, especially as we age in a rapidly changing environment? Evolutionary biology as proposed by Darwin with natural selection at its core may not be able to explain almost instant adjustments of phenotypic traits to the pressures of the environment. Epigenesis, a concept that dates from Aristotle, provides a mechanism for the environment to affect variation in genetic traits that may become heritable. Indeed, Lamarck first described the inheritance of acquired characteristics. Thus, it appears that in contemporary genetics, both Darwin and Lamarck are right: environmental pressures may affect our genes through epigenetics, in ways that allow for inheritance of the changes, a Lamarckian concept; however, evolution through natural selection is the basis for incorporation (or rejection) of new traits and their sustained inheritance, a Darwinian concept. In this review, we present the synthesis of Darwin's and Lamarck's theories, the only way to understand how our health, and that of our progeny, responds to challenging and fast-changing environmental cues. In addition, we present other examples of environment-driven changes in disease frequency or expression.

Trait-Specific Indirect Effects Underlie Variation in the Response of Spiders to Cannibalistic Social Partners.

AbstractIn cannibalistic species, selection to avoid conspecifics may stem from the need to avoid being eaten or to avoid competition. Individuals may thus use conspecific cues to modulate their behavior to such threats. Yet the nature of variation for such cues remains elusive. Here, we use a half-sib/full-sib design to evaluate the contribution of (indirect) genetic or environmental effects to the behavioral response of the cannibalistic wolf spider Lycosa fasciiventris (Dufour, 1835) toward conspecific cues. Spiders showed variation in relative occupancy time, activity, and velocity on patches with or without conspecific cues, but direct genetic variance was found only for occupancy time. These three traits were correlated and could be lumped in a principal component: spiders spending more time in patches with conspecific cues moved less and more slowly in those areas. Genetic and/or environmental components of carapace width and weight loss in the social partner, which may reflect the quality and/or quantity of cues produced, were significantly correlated with this principal component, with larger partners causing focal individuals to move more slowly. Therefore, environmental and genetic trait variation in social partners may maintain trait diversity in focal individuals, even in the absence of direct genetic variation.

Exploitation of heterosis in a diallel crosses of periwinkle (Catharanthus roseus) for morphological traits

Despite the economic significance of periwinkle [Catharanthus roseus (L.) G. Don] the existence of genetic variation in traits have been largely unexplored and very little attempt has been done to improve its genetics for ornamental prospective. An experiment was conducted at the research farm of Punjab Agricultural University, Ludhiana, Punjab during 2019 to 2021 using 6 inbred lines of periwinkle to develop 30 F1 populations in full-diallel fashion. The highly significant positive heterobeltiosis was recorded in the progeny of Vi-29 × Vi-14-3 for leaf breadth, follicle length, number of flowers per plant and number of seeds per follicle. The cross combination Vi-13-2 × Vi-29 was recorded significantly high heterobeltiosis for plant height and plant spread. The minimum heterobeltiosis was recorded for plant spread and follicle length in cross Vi-14-3 × Vi-15-1. The highest mean performance of the parents reported in Vi-15-1 for plant spread, internode length, flower diameter, number of flowers per plant, follicle length and number of seeds per follicle. As per the results among the cross combinations superior mean performance was observed in the Vi-15-1 × Vi-14-3 for leaf length and number of flowers per plant. These findings suggest that hybridization is an efficient way of contributing genetic variability in periwinkle for landscape utilization.

Estimation of additive genetic variance when there are gene–environment correlations: Pitfalls, solutions and unexplored questions

Abstract Estimating the genetic variation underpinning a trait is crucial to understanding and predicting its evolution. A key statistical tool to estimate this variation is the animal model. Typically, the environment is modelled as an external variable independent of the organism, affecting the focal phenotypic trait via phenotypic plasticity. We studied what happens if the environment is not independent of the organism because it chooses or adjusts its environment, potentially creating non‐zero genotype–environment correlations. We simulated a set of biological scenarios assuming the presence or absence of a genetic basis for a focal phenotypic trait and/or the focal environment (treated as an extended phenotype), as well as phenotypic plasticity (the effect of the environment on the phenotypic trait) and/or ‘environmental plasticity’ (the effect of the phenotypic trait on the local environment). We then estimated the additive genetic variance of the phenotypic trait and/or the environment by applying five animal models which differed in which variables were fitted as the dependent variable and which covariates were included. We show that animal models can estimate the additive genetic variance of the local environment (i.e. the extended phenotype) and can detect environmental plasticity. We show that when the focal environment has a genetic basis, the additive genetic variance of a phenotypic trait increases if there is phenotypic plasticity. We also show that phenotypic plasticity can be mistakenly inferred to exist when it is actually absent and instead environmental plasticity is present. When the causal relationship between the phenotype and the environment is misunderstood, it can lead to severe misinterpretation of the genetic parameters, including finding ‘phantom’ genetic variation for traits that, in reality, have none. We also demonstrate how using bivariate models can partly alleviate these issues. Finally, we provide the mathematical equations describing the expected estimated values. This study highlights that not taking gene–environment correlations into account can lead to erroneous interpretations of additive genetic variation and phenotypic plasticity estimates. If we aim to understand and predict how organisms adapt to environmental change, we need a better understanding of the mechanisms that may lead to gene–environment correlations.

Contrasting adaptive trait variation in response to drought in two Mediterranean shrubs

Adaptive evolution and phenotypic plasticity are key mechanisms of climate change responses. However, we still lack a detailed understanding of the strategies different species use to cope with climatic changes such as increased droughts, particularly for species with special edaphic requirements and limited dispersal such as gypsum endemics. In this study, we assessed phenotypic and genotypic selection, phenotypic plasticity and genetic variation in traits potentially related to drought response in two dominant gypsum Mediterranean species, Helianthemum squamatum and Centaurea hyssopifolia. We established a common garden in which 524 plants from 79 maternal families from both species were grown under two contrasting watering treatments. Our results revealed that selection was stronger under drought than well-watered conditions for both species, but we found contrasting adaptive strategies and genetic variation. In H. squamatum, a drought-escape strategy with advanced reproductive phenology and faster growth rates was positively associated with fitness under dry conditions, and most adaptive traits exhibited quantitative genetic variation. In contrast, in C. hyssopifolia, selection under dry conditions favored a drought-tolerance strategy with thicker leaves and longer phenologies, but all traits lacked quantitative genetic variation, indicating that their evolutionary potential may be limited. Most traits exhibited significant plasticity in response to drought and genetic variation for trait plasticity in both species, indicating that trait plasticity can evolve independently of the evolution of trait means in these gypsophiles. Our results show that these gypsum endemic species vary in strategies and adaptive potential in response to drought, which contributes to our understanding of potential adaptive responses to climate change in such edaphic specialists.

Exploring the efficiency of Ethyl Methane Sulfonate (EMS) and Sodium Azide (SA) to induce mutation in chili (Capsicum annuum L.) germplasm

BackgroundExploring genetic diversity in traits of interest and utilizing it to breed high yielding, disease-resistant and high market value varieties is the prime objective of plant breeders. Unfortunately, genetic diversity in most of the crops has declined due to selection and reutilization of already adapted germplasm. Chemical mutagens are widely used to create novel changes in germplasm; however, these have been rarely tested for chili germplasm in Pakistan. MethodsWe used ethyl methane sulfonate (EMS) and sodium azide (SA) to induce mutations for obtaining novel alterations in morphological and yield-related traits of four chili genotypes (i.e., ‘Mexi’, ‘Dandi Cut’, ‘Nageena’ and ‘Talhari’). Firstly, concentrations of both mutagens were calibrated, i.e., 1.5 % EMS and 0.5 % SA. Afterwards, seeds of four chili cultivars were treated and grown in peat trays. As the nursery was established, seedlings were transferred to media (sand: silt: clay + 1 kg well-decomposed FYM) after 30 days of germination. Different mutants were isolated based on differential morphological and phenotypic expressions. ResultsIt was found that efficiency of EMS was greater than SA and more variants were noticed in case of EMS-treated populations. Genetic analysis showed that almost all the traits were affected by mutagens in the M1 generations although the stability of isolated mutants was not checked in later generations. All the traits showed higher estimates of heritability but in some traits genetic advance was non-significant. ConclusionIt is recommended that isolated mutants could be used as rich genetic diversity source to breed new varieties. Furthermore, EMS proved a suitable mutagen for targeted mutations.

Evidence of climate-driven selection on tree traits and trait plasticity across the climatic range of a riparian foundation species.

Selection on quantitative traits by heterogeneous climatic conditions can lead to substantial trait variation across a species range. In the context of rapidly changing environments, however, it is equally important to understand selection on trait plasticity. To evaluate the role of selection in driving divergences in traits and their associated plasticities within a widespread species, we compared molecular and quantitative trait variation in Populus fremontii (Fremont cottonwood), a foundation riparian distributed throughout Arizona. Using SNP data and genotypes from 16 populations reciprocally planted in three common gardens, we first performed QST -FST analyses to detect selection on traits and trait plasticity. We then explored the environmental drivers of selection using trait-climate and plasticity-climate regressions. Three major findings emerged: (1) There was significant genetic variation in traits expressed in each of the common gardens and in the phenotypic plasticity of traits across gardens, both of which were heritable. (2) Based on QST -FST comparisons, there was evidence of selection in all traits measured; however, this result varied from no effect in one garden to highly significant in another, indicating that detection of past selection is environmentally dependent. We also found strong evidence of divergent selection on plasticity across environments for two traits. (3) Traits and/or their plasticity were often correlated with population source climate (R2 up to .77 and .66, respectively). These results suggest that steep climate gradients across the Southwest have played a major role in shaping the evolution of divergent phenotypic responses in populations and genotypes now experiencing climate change.

The role of genome duplication in big sagebrush growth and fecundity.

Adaptive traits can be dramatically altered by genome duplication. The study of interactions among traits, ploidy, and the environment are necessary to develop an understanding of how polyploidy affects niche differentiation and to develop restoration strategies for resilient native ecosystems. Growth and fecundity were measured in common gardens for 39 populations of big sagebrush (Artemisia tridentata) containing two subspecies and two ploidy levels. General linear mixed-effect models assessed how much of the trait variation could be attributed to genetics (i.e., ploidy and climatic adaptation), environment, and gene-environment interactions. Growth and fecundity variation were explained well by the mixed models (80% and 91%, respectively). Much of the trait variation was attributed to environment, and 15% of variation in growth and 34% of variation in seed yield were attributed to genetics. Genetic trait variation was mostly attributable to ploidy, with much higher growth and seed production in diploids, even in a warm-dry environment typically dominated by tetraploids. Population-level genetic variation was also evident and was related to the climate of each population's origin. Ploidy is a strong predictor growth and seed yield, regardless of common-garden environment. The superior growth and fecundity of diploids across environments raises the question as to how tetraploids can be more prevalent than diploids, especially in warm-dry environments. Two hypotheses that may explain the abundance of tetraploids on the landscape include selection for drought resistance at the seedling stage, and greater competitive ability in water uptake in the upper soil horizon.

Positive genetic covariance and limited thermal tolerance constrain tropical insect responses to global warming.

Tropical ectotherms are particularly vulnerable to global warming because their physiologies are assumed to be adapted to narrow temperature ranges. This study explores three mechanisms potentially constraining thermal adaptation to global warming in tropical insects: (a) Trade-offs in genotypic performance at different temperatures (the jack-of-all-trades hypothesis), (b) positive genetic covariance in performance, with some genotypes performing better than others at viable temperatures (the 'winner' and 'loser' genotypes hypothesis), or (c) limited genetic variation as the potential result of relaxed selection and the loss of genes associated with responses to extreme temperatures (the gene decay hypothesis). We estimated changes in growth and survival rates at multiple temperatures for three tropical rain forest insect herbivores (Cephaloleia rolled-leaf beetles, Chrysomelidae). We reared 2,746 individuals in a full sibling experimental design, at temperatures known to be experienced by this genus of beetles in nature (i.e. 10-35°C). Significant genetic covariance was positive for 16 traits, supporting the 'winner' and 'loser' genotypes hypothesis. Only two traits displayed negative cross-temperature performance correlations. We detected a substantial contribution of genetic variance in traits associated with size and mass (0%-44%), but low heritability in plastic traits such as development time (0%-6%) or survival (0%-4%). Lowland insect populations will most likely decline if current temperatures increase between 2 and 5°C. It is concerning that local adaption is already lagging behind current temperatures. The consequences of maintaining the current global warming trajectory would be devastating for tropical insects. However, if humans can limit or slow warming, many tropical ectotherms might persist in their current locations and potentially adapt to warmer temperatures.

Genetic variability for and tolerance to anaerobic germination in rice (Oryza sativa L.)

ABSTRACT Poor germination and seedling establishment under flooded conditions is a major bottleneck in the direct-seeding system of rice. The objectives of this study were to determine the genetic variability for traits associated with anaerobic germination and identify tolerant genotypes. One hundred rice genotypes were screened. Data were collected on survival percentage, shoot length, root length, length of plant above water, and seedling vigor index. Six clusters, which were generally related to the ability of the genotypes to tolerate anaerobic germination, were detected. The first two principal components accounted for 91.1% of the total variation, with survival percentage, seedling vigor index and shoot length being the main discriminatory traits. Genotypic coefficient of variation ranged from 18.21% for shoot length to 50.89% for seedling vigor index. Shoot length and seedling vigor index recorded high broad-sense heritability estimates (>60%), with accompanying high genetic advance as percent of mean (>20%); the latter ranged from 23.12% for root length to 82.21% for seedling vigor index. The high heritability, along with high genetic advance, particularly for shoot length and seedling vigor index, indicated that selection for these traits should be effective in improving tolerance to anaerobic germination. Five tolerant genotypes (OBOLO, ART68-12-1-1-B-B, ART64-31-1-1-B-B, CRI-1-21-5-12, and CRI-Enapa) with high survival percentage (≥70%) under anaerobic conditions were identified. These genotypes could be used to improve commercial rice varieties for tolerance to anaerobic germination.

Implications of emmer (Triticum dicoccon Schrank) introgression on bread wheat response to heat stress

Wheat is sensitive to heat stress, particularly during grain filling, and this reduces grain yield. Ancestral wheat species, such as emmer wheat (Triticum dicoccon Schrank), represent potential sources of new genetic diversity for traits that may impact wheat responses to heat stress. However, the diversity available in emmer wheat has only been explored superficially. Recently developed emmer derived hexaploid wheat genotypes were evaluated for physiological, phenological and agronomic traits in a multi-environment, multi-season strategy. The emmer-based hexaploid lines were developed from crosses and backcrosses to 9 hexaploid recurrent parents and these genotypes and 7 commercial cultivars were evaluated under two times of sowing (E1 and E2) in the field for three consecutive years (2014–2016). The materials were genotyped using a 90 K SNP platform and these data used to estimate the contribution of emmer wheat to the progeny. Significant phenotypic and genetic variation for traits were observed. Higher temperature during reproductive development and grain filling reduced trait expression. Emmer progeny with greater trait values than their recurrent parents and commercial cultivars in both environments were found. Derivatives with higher physiological trait values yielded well in both environments; as indicated by the clustering of genotypes. The emmer wheat parent contributed between 1 and 43 % of the genome of the emmer-based hexaploid progeny, and progeny with greater emmer contribution had superior trait values in both environments. These results showed a positive effect of direct emmer introgression on wheat performance under heat stress. Mitigation of high temperature stress through the introgression of favorable alleles from wheat close relatives into modern wheat cultivars is possible.

Multivariate Analysis of Genetic Diversity Among Okra (Abelmoschus spp.) Cultivars Grown in Côte d’Ivoire Based on Agro-morphological Traits

Crop improvement for sustainable agriculture requires information about the genetic variability of traits that helps identify suitable parents. This study was conducted to investigate the extent of genetic diversity among 12 okra cultivars grown and marketed in Côte d’Ivoire, using 12 quantitative and 11 qualitative agro-morphological traits. A Randomized Complete Block Design (RCBD) with five replications and two multivariate techniques, viz. principal component analysis (PCA) and cluster analysis (CA) were used. The okra cultivars evaluated showed wide variation in quantitative traits but minimal variation in qualitative traits except for leaf and fruit shapes. The first two PCs explained 70.489% variation and identify seven traits (day to flowering, stem diameter, plant height, number of fruit ridges, number of fruits per plant, fruit yield and number of seeds per fruit) that play a prominent role in the differentiation of the okra cultivars, and therefore could be used as good criteria for selection in okra improvement. PCA and CA grouped the total cultivars into three divergent clusters exhibiting specific characteristics: vigor and good yield for cluster I, short plants and earliness for cluster II and high yield for cluster III. The results of this investigation indicated that substantial variability was present in the okra studied. The cultivars of the divergent clusters constitute interesting okra genetic resources that can be used as a parental material for further breeding. Keywords: genetic diversity, okra, Abelmoschus caillei , Abelmoschus esculentus , principal component analysis, cluster analysis DOI: 10.7176/JBAH/10-22-03 Publication date: November 30 th 2020

Population Divergence along a Genetic Line of Least Resistance in the Tree Species Eucalyptus globulus.

The evolutionary response to selection depends on the distribution of genetic variation in traits under selection within populations, as defined by the additive genetic variance-covariance matrix (G). The structure and evolutionary stability of G will thus influence the course of phenotypic evolution. However, there are few studies assessing the stability of G and its relationship with population divergence within foundation tree species. We compared the G-matrices of Mainland and Island population groups of the forest tree Eucalyptus globulus, and determined the extent to which population divergence aligned with within-population genetic (co)variation. Four key wood property traits exhibiting signals of divergent selection were studied—wood density, extractive content, and lignin content and composition. The comparison of G-matrices of the mainland and island populations indicated that the G-eigenstructure was relatively well preserved at an intra-specific level. Population divergence tended to occur along a major direction of genetic variation in G. The observed conservatism of G, the moderate evolutionary timescale, and close relationship between genetic architecture and population trajectories suggest that genetic constraints may have influenced the evolution and diversification of the E. globulus populations for the traits studied. However, alternative scenarios, including selection aligning genetic architecture and population divergence, are discussed.

Quantitative trait variation, phenotypic integration, and plasticity to elevated carbon dioxide in four recombinant inbred populations of Arabidopsis thaliana (Brassicaceae)

Rapid changes in the concentration of atmospheric carbon dioxide, a key driver of global climate change, have been shown to affect ecologically important traits in plants. Characterizing the effects of novel genetic variation on quantitative variation, phenotypic integration (multivariate associations among traits), and plasticity to elevated carbon dioxide can shed light on short-term plant responses to climate change. Here we explored univariate and multivariate responses to elevated carbon dioxide among four recombinant inbred populations of Arabidopsis thaliana established from genetically divergent ecotypes crossed to a common genetic background. We found significant genetic variation in all traits, but no genetic variation in phenotypic plasticity (i.e., genotype by environment interactions) in any trait among recombinant inbred lines. Significant cross-environment correlation in fitness values showed similar patterns of selection between ambient and elevated carbon dioxide treatments. Our data suggest that outcrossing among A. thaliana ecotypes increases genetic variation in functional traits, but makes little or no contribution to genotype by environment interactions and patterns of phenotypic integration. However, multivariate analyses revealed shifts in patterns of phenotypic integration in response to elevated carbon dioxide. We conclude that multivariate plasticity will likely play an important role in shaping short-term responses to future carbon dioxide conditions in natural populations of A. thaliana.

Competition×drought interactions change phenotypic plasticity and the direction of selection on Arabidopsis traits.

Populations often exhibit genetic diversity in traits involved in responses to abiotic stressors, but what maintains this diversity is unclear. Arabidopsis thaliana exhibits high within-population variation in drought response. One hypothesis is that competition, varying at small scales, promotes diversity in resource use strategies. However, little is known about natural variation in competition effects on Arabidopsis physiology. We imposed drought and competition treatments on diverse genotypes. We measured resource economics traits, physiology, and fitness to characterize plasticity and selection in response to treatments. Plastic responses to competition differed depending on moisture availability. We observed genotype-drought-competition interactions for relative fitness: competition had little effect on relative fitness under well-watered conditions, whereas competition caused rank changes in fitness under drought. Early flowering was always selected. Higher δ13 C was selected only in the harshest treatment (drought and competition). Competitive context significantly changed the direction of selection on aboveground biomass and inflorescence height in well-watered environments. Our results highlight how local biotic conditions modify abiotic selection, in some cases promoting diversity in abiotic stress response. The ability of populations to adapt to environmental change may thus depend on small-scale biotic heterogeneity.

Epigenetic Variation at a Genomic Locus Affecting Biomass Accumulation under Low Nitrogen in Arabidopsis thaliana

Nitrogen (N) is a macronutrient determining crop yield. The application of N fertilisers can substantially increase the yield, but excess use also causes the nitrate pollution of water resources and increases production costs. Increasing N use efficiency (NUE) in crop plants is an important step to implement low-input agricultural systems. We used Arabidopsis thaliana as model system to investigate the natural genetic diversity in traits related to NUE. Natural variation was used to study adaptive growth patterns and changes in gene expression associated with limited nitrate availability. A genome-wide association study revealed an association of eight SNP markers on Chromosome 1 with shoot growth under limited N. The identified linkage disequilibrium (LD) interval includes the DNA sequences of three cysteine/histidine-rich C1 domain proteins in tandem orientation. These genes differ in promoter structure, methylation pattern and expression level among accessions, correlating with growth performance under N deficiency. Our results suggest the involvement of epigenetic regulation in the expression of NUE-related traits.

Genomics of sorghum local adaptation to a parasitic plant

Host-parasite coevolution can maintain high levels of genetic diversity in traits involved in species interactions. In many systems, host traits exploited by parasites are constrained by use in other functions, leading to complex selective pressures across space and time. Here, we study genome-wide variation in the staple crop Sorghum bicolor (L.) Moench and its association with the parasitic weed Striga hermonthica (Delile) Benth., a major constraint to food security in Africa. We hypothesize that geographic selection mosaics across gradients of parasite occurrence maintain genetic diversity in sorghum landrace resistance. Suggesting a role in local adaptation to parasite pressure, multiple independent loss-of-function alleles at sorghum LOW GERMINATION STIMULANT 1 (LGS1) are broadly distributed among African landraces and geographically associated with S. hermonthica occurrence. However, low frequency of these alleles within S. hermonthica-prone regions and their absence elsewhere implicate potential trade-offs restricting their fixation. LGS1 is thought to cause resistance by changing stereochemistry of strigolactones, hormones that control plant architecture and below-ground signaling to mycorrhizae and are required to stimulate parasite germination. Consistent with trade-offs, we find signatures of balancing selection surrounding LGS1 and other candidates from analysis of genome-wide associations with parasite distribution. Experiments with CRISPR-Cas9-edited sorghum further indicate that the benefit of LGS1-mediated resistance strongly depends on parasite genotype and abiotic environment and comes at the cost of reduced photosystem gene expression. Our study demonstrates long-term maintenance of diversity in host resistance genes across smallholder agroecosystems, providing a valuable comparison to both industrial farming systems and natural communities.

Stoichiometric Traits Vary Widely Within Species: A Meta-Analysis of Common Garden Experiments

“Ecological stoichiometry,” a framework that focuses explicitly on the balances and flows of chemical elements within and between organisms and ecosystems, has provided crucial insights into many biological patterns and processes. Despite the proliferation of stoichiometrically-focused studies in recent decades and recognition of the potential for rapid evolution of stoichiometric traits, the prevalence of genetic variation in stoichiometric traits within species remains unclear. We compiled data from 30 published common garden studies of a broad range of taxa (including invertebrates, vertebrates, and autotrophs) to examine how genetic variation influences the acquisition, assimilation, allocation (AAA), composition, and excretion of elements. To quantify the extent of genetic variation for a given trait we calculated the absolute mean response ratio from pairwise comparisons of populations within the same common garden (820 population and 708 genotype comparisons). We observed substantial intraspecific variation of stoichiometric traits across populations and among genotypes; however, the magnitude of variation was greater in AAA traits (effect sizes of 20 and 164% for population and genotype contrasts, respectively) and excretion (effect sizes of 52 and 23%) than in content of carbon (2.1 and 3.1%) and nitrogen (4.5 and 24%). These results suggest that the content of some elements may be evolutionarily constrained relative to AAA traits that determine the processing of these elements, and that a sole focus on elemental content would underestimate the importance of intraspecific genetic variation, particularly within populations. Across many trait types the variation was greater among genotypes within a population than across populations. Finally, we compared pairs of populations from environments with different phosphorus (P) availability to pairs of populations with similar P availability. Genetic variation in the traits measured was similar regardless of the P environment from which genotypes were isolated, suggesting that differences in elemental availability across environments do not necessarily drive enhanced trait divergence. Overall, our results highlight the substantial amount of intraspecific variation in stoichiometric traits and underscore the potential importance of intraspecific variation in driving ecological and evolutionary processes.

Temperature‐induced developmental plasticity in Plodia interpunctella: Reproductive behaviour and sperm length

In both plants and animals, male gametogenesis is particularly sensitive to heat stress, to the extent that a single hot or cold day can compromise crop productivity or population persistence. In animals, heat stress during development can impact a male's ability to secure copulations and/or his post-copulatory fertility. Despite such observations, relatively few studies have examined the consequences of developmental temperature on the reproductive behaviour and physiology of individuals. Here, we report for the first time the effects of developmental temperature on the phenotypic expression of both apyrene and eupyrene sperm and the copulatory behaviour of the Indian meal moth, Plodia interpunctella. We show that the length of both apyrene and eupyrene sperm decreases with increasing developmental temperature and that males are less likely to engage in copulation when reared at the highest and lowest temperatures. Where copulation occurred, the duration of copula decreased as male developmental temperature increased. We argue that identification of the mechanisms and consequences of reproductive failure in animals facing heat stress will help understand how wild and domesticated populations will respond to global climate change. We also contend that such studies will help elucidate long-standing evolutionary questions around the maintenance of genetic variation in traits highly relevant to fitness and the role of phenotypic plasticity in driving the evolution of novel traits.

From markers to genome-based breeding in wheat.

Recent technological advances in wheat genomics provide new opportunities to uncover genetic variation in traits of breeding interest and enable genome-based breeding to deliver wheat cultivars for the projected food requirements for 2050. There has been tremendous progress in development of whole-genome sequencing resources in wheat and its progenitor species during the last 5years. High-throughput genotyping is now possiblein wheat not only for routine gene introgression but also for high-density genome-wide genotyping. This is a major transition phase to enable genome-based breeding to achieve progressive genetic gains to parallel to projected wheat production demands. These advances have intrigued wheat researchers to practice less pursued analytical approaches which were not practiced due to the short history of genome sequence availability. Such approaches have been successful in gene discovery and breeding applications in other crops and animals for which genome sequences have been available for much longer. Thesestrategies include, (i) environmentalgenome-wide association studies in wheat genetic resources stored in genbanks to identify genes for local adaptationby using agroclimatic traits as phenotypes, (ii) haplotype-based analyses to improve the statistical power and resolution of genomic selection and gene mapping experiments, (iii) new breeding strategies for genome-based prediction of heterosis patterns in wheat, and (iv) ultimate use of genomics information to develop more efficient and robust genome-wide genotyping platforms to precisely predict higher yield potential and stability with greater precision. Genome-based breeding has potential to achieve the ultimate objective of ensuring sustainable wheat production through developing high yielding, climate-resilient wheat cultivars with high nutritional quality.