scholarly journals Artificial selection on male size depletes genetic variance but not covariance of life history traits in the yellow dung fly

2019 ◽  
Author(s):  
WU Blanckenhorn ◽  
V Llaurens ◽  
C Reim ◽  
Y Teuschl ◽  
E Postma
Keyword(s):  
Genetic Variation ◽  
Life History ◽  
Body Size ◽  
Artificial Selection ◽  
Development Time ◽  
Life History Traits ◽  
Genetic Variance ◽  
Genetic Correlations ◽  
Male Size ◽  
First Clutch

SUMMARYThe evolutionary potential of organisms depends on the presence of sufficient genetic variation for traits subject to selection, as well as on the genetic covariances among them. While genetic variation ultimately derives from mutation, theory predicts the depletion of genetic (co)variation under consistent directional or stabilizing selection in natural populations. We estimated and compared additive genetic (co)variances for several standard life history traits, including some for which this has never been assessed, before and after 24 generations of artificial selection on male size in the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae) using a series of standard half-sib breeding experiments. As predicted, genetic variances (VA), heritabilities (h2) and evolvabilities (IA) of body size, development time, first clutch size, and female age at first clutch were lower after selection. As independent selection lines were crossed prior to testing, we can rule out that this reduction is due to genetic drift. In contrast to the variances, and against expectation, the additive genetic correlations between the sexes for development time and body size remained strong and positive (rA = 0.8–0.9), while the genetic correlation between these traits within the sexes tended to strengthen (but not significantly so). Our study documents that the effect of selection on genetic variance is predictable, whereas that on genetic correlations is not.

scholarly journals Seasonality and genetic architecture of development time and body size of the birch feeding sawfly Priophorus pallipes

2001 ◽  
Vol 78 (1) ◽  
pp. 31-40 ◽  
Author(s):  
ANTTI KAUSE ◽  
JEAN-PHILIPPE MORIN
Keyword(s):  
Genetic Variation ◽  
Body Size ◽  
Diet Quality ◽  
Development Time ◽  
Genetic Correlations ◽  
Reaction Norms ◽  
High Quality ◽  
Genetic Characteristics ◽  
Mature Leaves ◽  
Final Mass

We tested, using the sawfly Priophorus pallipes feeding on leaves of mountain birch, whether the expression of genetic (co)variation of larval development time and body size can be altered by exposing larvae to diets with differential seasonal changes in quality. In nature, larvae feed mainly on mature leaves, but occasionally they are forced to consume senescing leaves. Sixty families were assayed on three experimentally simulated diets: mature leaves of high quality, senescing leaves of rapidly declining quality, and senesced leaves of low quality. The intuitively obvious positive phenotypic and genetic correlations between development time and final mass were observed when the larvae consumed leaves of stable high quality, but low and declining food quality prevented long-growing individuals and families from achieving high final mass, switching the correlations to close to zero or negative in these treatments. The amount of genetic variation for body size showed a non-linear change across the diet quality gradient, whereas genetic variation for development time increased with decreasing diet quality. The among-trait difference in the degree reaction norms crossed along the diet gradient caused the changes in the expression of genetic (co)variation within the environments. Our results show that seasonally varying diet quality induces dramatic changes in the genetic (co)variation of development time and body size, and that simultaneous analysis of reaction norms and environment-specific expression of genetic (co)variation is necessary for the understanding of the genetic characteristics underlying the construction of phenotypes in heterogeneous environments.

scholarly journals Unidirectional response to bidirectional selection on body size II Quantitative genetics

2020 ◽  
Author(s):  
Arnaud Le Rouzic ◽  
Clémentine Renneville ◽  
Alexis Millot ◽  
Simon Agostini ◽  
David Carmignac ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Body Length ◽  
Quantitative Genetics ◽  
Artificial Selection ◽  
Life History Traits ◽  
Random Effect ◽  
Control Line ◽  
Early Maturity ◽  
And Control

AbstractAnticipating the genetic and phenotypic changes induced by natural or artificial selection requires reliable estimates of trait evolvabilities (genetic variances and covariances). However, whether or not multivariate quantitative genetics models are able to predict precisely the evolution of traits of interest, especially fitness-related, life-history traits, remains an open empirical question. Here, we assessed to what extent the response to bivariate artificial selection on both body size and maturity in the medaka Oryzias latipes, a model fish species, fits the theoretical predictions. Three lines (Large, Small, and Control lines) were differentially selected for body length at 75 days of age, conditional on maturity. As maturity and body size were phenotypically correlated, this selection procedure generated a bi-dimensional selection pattern on two life history traits. After removal of non-heritable trends and noise with a random effect (’animal’) model, the observed selection response did not match the expected bidirectional response. For body size, Large and Control lines responded along selection gradients (larger body size and stasis, respectively), but, surprisingly, the Small did not evolve a smaller body length, and remained identical to the Control line throughout the experiment. The magnitude of the empirical response was smaller than the theoretical prediction in both selected directions. For maturity, the response was opposite to the expectation (the Large line evolved late maturity compared to the Control line, while the Small line evolved early maturity, while the opposite pattern was predicted due to the strong positive genetic correlation between both traits). The mismatch between predicted and observed response was substantial and could not be explained by usual sources of uncertainties (including sampling effects, genetic drift, and error in G matrix estimates).

scholarly journals Genetic variation and covariation of aphid life-history traits across unrelated host plants

2008 ◽  
Vol 98 (6) ◽  
pp. 543-553 ◽  
Author(s):  
C. Vorburger ◽  
N. Ramsauer
Keyword(s):  
Genetic Variation ◽  
Life History ◽  
Host Plants ◽  
Life History Theory ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Covariance Structure ◽  
Clonal Variation ◽  
Common Lambsquarters ◽  
Trade Offs

AbstractA central paradigm of life-history theory is the existence of resource mediated trade-offs among different traits that contribute to fitness, yet observations inconsistent with this tenet are not uncommon. We previously found a clonal population of the aphid Myzus persicae to exhibit positive genetic correlations among major components of fitness, resulting in strong heritable fitness differences on a common host. This raises the question of how this genetic variation is maintained. One hypothesis states that variation for resource acquisition on different hosts may override variation for allocation, predicting strong fitness differences within hosts as a rule, but changes in fitness hierarchies across hosts due to trade-offs. Therefore, we carried out a life-table experiment with 17 clones of M. persicae, reared on three unrelated host plants: radish, common lambsquarters and black nightshade. We estimated the broad-sense heritabilities of six life-history traits on each host, the genetic correlations among traits within hosts, and the genetic correlations among traits on different hosts (cross-environment genetic correlations). The three plants represented radically different environments with strong effects on performance of M. persicae, yet we detected little evidence for trade-offs. Fitness components were positively correlated within hosts but also between the two more benign hosts (radish and lambsquarters), as well as between those and another host tested earlier. The comparison with the most stressful host, nightshade, was hampered by low survival. Survival on nightshade also exhibited genetic variation but was unrelated to fitness on other hosts. Acknowledging that the number of environments was necessarily limited in a quantitative genetic experiment, we suggest that the rather consistent fitness hierarchies across very different plants provided little evidence to support the idea that the clonal variation for life-history traits and their covariance structure are maintained by strong genotype×environment interactions with respect to hosts. Alternative explanations are discussed.

scholarly journals Where do all the maternal effects go? Variation in offspring body size through ontogeny in the live-bearing fish Poecilia parae

2006 ◽  
Vol 2 (4) ◽  
pp. 586-589 ◽  
Author(s):  
Anna K Lindholm ◽  
John Hunt ◽  
Robert Brooks
Keyword(s):  
Body Size ◽  
Maternal Effects ◽  
Variance Components ◽  
Sexual Maturity ◽  
Compensatory Growth ◽  
Life History Traits ◽  
Genetic Variance ◽  
Adult Longevity ◽  
Male Size ◽  
Sharp Rise

Abstract Maternal effects are an important source of adaptive variation, but little is known about how they vary throughout ontogeny. We estimate the contribution of maternal effects, sire genetic and environmental variation to offspring body size from birth until 1 year of age in the live-bearing fish Poecilia parae . In both the sexes, maternal effects on body size were initially high in juveniles, and then declined to zero at sexual maturity. In sons, this was accompanied by a sharp rise in sire genetic variance, consistent with the expression of Y-linked loci affecting male size. In daughters, all variance components decreased with time, consistent with compensatory growth. There were significant negative among-dam correlations between early body size and the timing of sexual maturity in both sons and daughters. However, there was no relationship between early life maternal effects and adult longevity, suggesting that maternal effects, although important early in life, may not always influence late life-history traits.

scholarly journals Allelic polymorphism at foxo contributes to local adaptation in Drosophila melanogaster

2018 ◽  
Author(s):  
Nicolas J. Betancourt ◽  
Subhash Rajpurohit ◽  
Esra Durmaz ◽  
Daniel K. Fabian ◽  
Martin Kapun ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life History ◽  
Body Size ◽  
Local Adaptation ◽  
Development Time ◽  
Genetic Variance ◽  
Allelic Variation ◽  
Natural Populations ◽  
Life History Variation ◽  
Starvation Tolerance

AbstractThe insulin insulin-like growth factor signaling pathway has been hypothesized as a major determinant of life history profiles that vary adaptively in natural populations. In Drosophila melanogaster, multiple components of this pathway vary predictably with latitude; this includes foxo, a conserved gene that regulates insulin signaling and has pleiotropic effects on a variety of fitness-associated traits. We hypothesized that allelic variation at foxo underlies genetic variance for traits that vary with latitude and reflect local adaptation. To evaluate this, we generated recombinant outbred populations in which the focal foxo allele was homozygous and fixed for either the allele common at high latitude or low latitude and the genomic background was randomized across 20 inbred lines. After eight generations of recombination, experimental populations were phenotyped for a series of traits related to gene function. Our results demonstrate that natural allelic variation at foxo has major and predictable effects on body size and starvation tolerance, but not on development time. These patterns mirror those observed in natural populations collected across the latitudinal gradient in the eastern U.S.: clines were observed for starvation tolerance and body size, but development time exhibited no association with latitude. Furthermore, differences in size between foxo genotypes were equivalent to those observed between populations sampled from the latitudinal extremes, although contribution to the genetic variance for starvation tolerance was less pronounced. These results suggest that allelic variation at foxo is a major contributor to adaptive patterns of life history variation in natural populations of this genetic model.

scholarly journals Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments

2021 ◽  
Author(s):  
Anik Dutta ◽  
Fanny E. Hartmann ◽  
Carolina Sardinha Francisco ◽  
Bruce A. McDonald ◽  
Daniel Croll
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Stress Factors ◽  
Life History Trait ◽  
Adaptive Landscape ◽  
Heterogeneous Environments ◽  
Growth Responses ◽  
Trade Offs

AbstractThe adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen’s ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.

Comparing Mutational Variabilities

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1467-1483 ◽  
Author(s):  
David Houle ◽  
Bob Morikawa ◽  
Michael Lynch
Keyword(s):  
Life History ◽  
Morphological Traits ◽  
Life History Traits ◽  
Genetic Variance ◽  
Balance Model ◽  
Phenotypic Traits ◽  
Infinite Population ◽  
Persistence Time ◽  
Coefficients Of Variation ◽  
Balance Hypothesis

Abstract We have reviewed the available data on VM, the amount of genetic variation in phenotypic traits produced each generation by mutation. We use these data to make several qualitative tests of the mutation-selection balance hypothesis for the maintenance of genetic variance (MSB). To compare VM values, we use three dimensionless quantities: mutational heritability, the mutational coefficient of variation, CVM; and the ratio of the standing genetic variance to VM, VG/VM. Since genetic coefficients of variation for life history traits are larger than those for morphological traits, we predict that under MSB, life history traits should also have larger CVM. This is confirmed; life history traits have a median CVM value more than six times higher than that for morphological traits. VG/VM approximates the persistence time of mutations under MSB in an infinite population. In order for MSB to hold, VG/VM must be small, substantially less than 1000, and life history traits should have smaller values than morphological traits. VG/VM averages about 50 generations for life history traits and 100 generations for morphological traits. These observations are all consistent with the predictions of a mutation-selection balance model.

Differential effects on life history traits and body size of two anuran species inhabiting an environment related to fluorite mine

2018 ◽  
Vol 93 ◽  
pp. 36-44 ◽  
Author(s):  
Manuel A. Otero ◽  
Favio E. Pollo ◽  
Pablo R. Grenat ◽  
Nancy E. Salas ◽  
Adolfo L. Martino
Keyword(s):  
Life History ◽  
Body Size ◽  
Life History Traits ◽  
Differential Effects ◽  
Anuran Species

scholarly journals Loci, genes, and gene networks associated with life history variation in a model ecological organism,Daphnia pulex(complex)

2018 ◽  
Author(s):  
Jacob W. Malcom ◽  
Thomas E. Juenger ◽  
Mathew A. Leibold
Keyword(s):  
Gene Expression ◽  
Genetic Variation ◽  
Life History ◽  
Molecular Basis ◽  
Life History Traits ◽  
Evolutionary Dynamics ◽  
Daphnia Pulex ◽  
Life History Trait ◽  
Life History Variation ◽  
Trait Variation

ABSTRACTBackgroundIdentifying the molecular basis of heritable variation provides insight into the underlying mechanisms generating phenotypic variation and the evolutionary history of organismal traits. Life history trait variation is of central importance to ecological and evolutionary dynamics, and contemporary genomic tools permit studies of the basis of this variation in non-genetic model organisms. We used high density genotyping, RNA-Seq gene expression assays, and detailed phenotyping of fourteen ecologically important life history traits in a wild-caught panel of 32Daphnia pulexclones to explore the molecular basis of trait variation in a model ecological species.ResultsWe found extensive phenotypic and a range of heritable genetic variation (~0 < H2< 0.44) in the panel, and accordingly identify 75-261 genes—organized in 3-6 coexpression modules—associated with genetic variation in each trait. The trait-related coexpression modules possess well-supported promoter motifs, and in conjunction with marker variation at trans- loci, suggest a relatively small number of important expression regulators. We further identify a candidate genetic network with SNPs in eight known transcriptional regulators, and dozens of differentially expressed genes, associated with life history variation. The gene-trait associations include numerous un-annotated genes, but also support several a priori hypotheses, including an ecdysone-induced protein and several Gene Ontology pathways.ConclusionThe genetic and gene expression architecture ofDaphnialife history traits is complex, and our results provide numerous candidate loci, genes, and coexpression modules to be tested as the molecular mechanisms that underlieDaphniaeco-evolutionary dynamics.

scholarly journals Life history and habitat do not mediate temporal changes in body size due to climate warming in rodents

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9792
Author(s):  
Aluwani Nengovhela ◽  
Christiane Denys ◽  
Peter J. Taylor
Keyword(s):  
Life History ◽  
Body Size ◽  
Climate Warming ◽  
Life History Traits ◽  
Vegetation Type ◽  
Reproductive Rate ◽  
Temporal Changes ◽  
Temporal Response ◽  
Extrinsic Factors ◽  
African Species

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.

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