scholarly journals Drosophila bristles and the nature of quantitative genetic variation

2005 ◽  
Vol 360 (1459) ◽  
pp. 1513-1527 ◽  
Author(s):  
Trudy F.C Mackay ◽  
Richard F Lyman
Keyword(s):  
Quantitative Traits ◽  
Natural Variation ◽  
Genetic Basis ◽  
Linkage Disequilibrium Mapping ◽  
Catecholamine Biosynthesis ◽  
Specific Effects ◽  
Bristle Number ◽  
Ideal Model System ◽  
Individual Candidate ◽  
Sensory Bristles

Numbers of Drosophila sensory bristles present an ideal model system to elucidate the genetic basis of variation for quantitative traits. Here, we review recent evidence that the genetic architecture of variation for bristle numbers is surprisingly complex. A substantial fraction of the Drosophila genome affects bristle number, indicating pervasive pleiotropy of genes that affect quantitative traits. Further, a large number of loci, often with sex- and environment-specific effects that are also conditional on background genotype, affect natural variation in bristle number. Despite this complexity, an understanding of the molecular basis of natural variation in bristle number is emerging from linkage disequilibrium mapping studies of individual candidate genes that affect the development of sensory bristles. We show that there is naturally segregating genetic variance for environmental plasticity of abdominal and sternopleural bristle number. For abdominal bristle number this variance can be attributed in part to an abnormal abdomen -like phenotype that resembles the phenotype of mutants defective in catecholamine biosynthesis. Dopa decarboxylase ( Ddc ) encodes the enzyme that catalyses the final step in the synthesis of dopamine, a major Drosophila catecholamine and neurotransmitter. We found that molecular polymorphisms at Ddc are indeed associated with variation in environmental plasticity of abdominal bristle number.

scholarly journals The genetic architecture underlying prey-dependent performance in a microbial predator

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Balint Stewart ◽  
Nicole Gruenheit ◽  
Amy Baldwin ◽  
Rex Chisholm ◽  
Daniel Rozen ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Genetic Architecture ◽  
Natural Variation ◽  
Genetic Basis ◽  
Prey Type ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Antagonistic Pleiotropy ◽  
Relative Importance ◽  
Specific Effects

AbstractNatural selection should favour generalist predators that outperform specialists across all prey types. Two genetic solutions could explain why intraspecific variation in predatory performance is, nonetheless, widespread: mutations beneficial on one prey type are costly on another (antagonistic pleiotropy), or mutational effects are prey-specific, which weakens selection, allowing variation to persist (relaxed selection). To understand the relative importance of these alternatives, we characterised natural variation in predatory performance in the microbial predator Dictyostelium discoideum. We found widespread nontransitive differences among strains in predatory success across different bacterial prey, which can facilitate stain coexistence in multi-prey environments. To understand the genetic basis, we developed methods for high throughput experimental evolution on different prey (REMI-seq). Most mutations (~77%) had prey-specific effects, with very few (~4%) showing antagonistic pleiotropy. This highlights the potential for prey-specific effects to dilute selection, which would inhibit the purging of variation and prevent the emergence of an optimal generalist predator.

scholarly journals Hybrid dysgenesis-induced quantitative variation on the X chromosome of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 627-636
Author(s):  
C Q Lai ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Quantitative Traits ◽  
Natural Populations ◽  
Quantitative Variation ◽  
Hybrid Dysgenesis ◽  
X Chromosomes ◽  
Bristle Number ◽  
Seven Generations ◽  
Polygenic Variation

Abstract To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgenic cross, a nondysgenic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high-of the same magnitude as heritabilities of these traits in natural populations. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgenic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females, a result consistent with previous observations on mutations affecting quantitative traits arising from nondysgenic crosses. The new variation resulting from one generation of mutagenesis was caused by a few lines with large effects on bristle score, and all mutations reduced bristle number.

scholarly journals Can artificially selected phenotypes influence a component of field fitness? Thermal selection and fly performance under thermal extremes

2006 ◽  
Vol 274 (1611) ◽  
pp. 771-778 ◽  
Author(s):  
Torsten Nygaard Kristensen ◽  
Volker Loeschcke ◽  
Ary A Hoffmann
Keyword(s):  
High Performance ◽  
Quantitative Traits ◽  
Genetic Basis ◽  
Selected Lines ◽  
Resistant Lines ◽  
Correlated Patterns ◽  
Different Temperatures ◽  
Evolutionary Trajectories ◽  
Low Performance ◽  
Selected Traits

Artificially selected lines are widely used to investigate the genetic basis of quantitative traits and make inferences about evolutionary trajectories. Yet, the relevance of selected traits to field fitness is rarely tested. Here, we assess the relevance of thermal stress resistance artificially selected in the laboratory to one component of field fitness by investigating the likelihood of adult Drosophila melanogaster reaching food bait under different temperatures. Lines resistant to heat reached the bait more often than controls under hot and cold conditions, but less often at intermediate temperatures, suggesting a fitness cost of increased heat resistance but not at temperature extremes. Cold-resistant lines were more common at baits than controls under cold as well as hot field conditions, and there was no cost at intermediate temperatures. One of the replicate heat-resistant lines was caught less often than the others under hot conditions. Direct and correlated patterns of responses in laboratory tests did not fully predict the low performance of the heat selected lines at intermediate temperatures, nor the high performance of the cold selected lines under hot conditions. Therefore, lines selected artificially not only behaved partly as expected based on laboratory assays but also evolved patterns only evident in the field releases.

Blood Uric Acid Level and IQ: A Study in Twin Families

1984 ◽  
Vol 33 (2) ◽  
pp. 237-242 ◽  
Author(s):  
E. Inouye ◽  
K.S. Park ◽  
A. Asaka
Keyword(s):  
Uric Acid ◽  
Uric Acid Level ◽  
Quantitative Traits ◽  
Acid Level ◽  
Genetic Basis ◽  
Plasma Uric Acid ◽  
Blood Uric Acid ◽  
Twin Children ◽  
Twin Families ◽  
Familial Environment

AbstractApplying newly devised model, heritability (VA/VP) of plasma uric acid level, corrected for age and sex and standardized, was estimated at 0.8 in families consisting of twin parents, spouses and children. Correlation between spouses due to common genotype (ρ) was approximately 0.1, and variance due to common familial environment (VEC/Vp) was -0.3. Analysis of families of selected twin children and their parents resulted in two estimates of heritability: approximately 0.7 and 0.3, ρ being 0.34 and 0.04, and VEC/Vp being 0.04 and 0.34, respectively. Regression of IQ (y) on corrected and standardized plasma uric acid level (x) in the twin children was y = 5.56x + 123, correlation being 0.334 (p < 0.025). The result indicates a genetic basis of blood uric acid level, which may have resulted from polymorphisms in purine metabolism pathway, end product of which is uric acid in man. The significant correlation between plasma uric acid level and IQ suggests a contribution of partly common gene loci to the two quantitative traits.

scholarly journals The Genetic Basis of Natural Variation in Drosophila melanogaster Immune Defense against Enterococcus faecalis

Genes ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 234 ◽  
Author(s):  
Joanne R Chapman ◽  
Maureen A Dowell ◽  
Rosanna Chan ◽  
Robert L Unckless
Keyword(s):  
Drosophila Melanogaster ◽  
Enterococcus Faecalis ◽  
Natural Variation ◽  
Genetic Basis ◽  
Genome Wide Association Study ◽  
Association Studies ◽  
Immune Defense ◽  
Nucleotide Polymorphisms ◽  
Disease Response ◽  
A Genome

Dissecting the genetic basis of natural variation in disease response in hosts provides insights into the coevolutionary dynamics of host-pathogen interactions. Here, a genome-wide association study of Drosophila melanogaster survival after infection with the Gram-positive entomopathogenic bacterium Enterococcus faecalis is reported. There was considerable variation in defense against E. faecalis infection among inbred lines of the Drosophila Genetics Reference Panel. We identified single nucleotide polymorphisms associated with six genes with a significant (p < 10−08, corresponding to a false discovery rate of 2.4%) association with survival, none of which were canonical immune genes. To validate the role of these genes in immune defense, their expression was knocked-down using RNAi and survival of infected hosts was followed, which confirmed a role for the genes krishah and S6k in immune defense. We further identified a putative role for the Bomanin gene BomBc1 (also known as IM23), in E. faecalis infection response. This study adds to the growing set of association studies for infection in Drosophila melanogaster and suggests that the genetic causes of variation in immune defense differ for different pathogens.

scholarly journals An ultra-high-density map as a community resource for discerning the genetic basis of quantitative traits in maize

BMC Genomics ◽  
2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Hongjun Liu ◽  
Yongchao Niu ◽  
Pedro J. Gonzalez-Portilla ◽  
Huangkai Zhou ◽  
Liya Wang ◽  
...  
Keyword(s):  
Quantitative Traits ◽  
Genetic Basis ◽  
High Density ◽  
Community Resource ◽  
Density Map

scholarly journals Temporal uniformity of the spontaneous mutational variance of quantitative traits in Drosophila melanogaster

2000 ◽  
Vol 75 (1) ◽  
pp. 47-51 ◽  
Author(s):  
AURORA GARCÍA-DORADO ◽  
JESUS FERNÁNDEZ ◽  
CARLOS LÓPEZ-FANJUL
Keyword(s):  
Drosophila Melanogaster ◽  
Morphological Traits ◽  
Quantitative Traits ◽  
Wing Length ◽  
Environment Interaction ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
Sib Mating ◽  
Mutational Variance ◽  
Interaction Variance

Spontaneous mutations were allowed to accumulate over 209 generations in more than 100 lines, all of them independently derived from a completely homozygous population of Drosophila melanogaster and subsequently maintained under strong inbreeding (equivalent to full-sib mating). Traits scored were: abdominal (AB) and sternopleural (ST) bristle number, wing length (WL) and egg-to-adult viability (V). On two occasions – early (generations 93–122) and late (generations 169–209) – ANOVA estimates of the mutational variance and the mutational line × generation interaction variance were obtained. Mutational heritabilities of morphological traits ranged from 2 × 10−4 to 2 × 10−3 and the mutational coefficient of variation of viability was 0·01. For AB, WL and V, temporal uniformity of the mutational variance was observed. However, a fluctuation of the mutational heritability of ST was detected and could be ascribed to random genotype × environment interaction.

scholarly journals Optimizing the Power to Identify the Genetic Basis of Complex Traits with Evolve and Resequence Studies

2019 ◽  
Vol 36 (12) ◽  
pp. 2890-2905 ◽  
Author(s):  
Christos Vlachos ◽  
Robert Kofler
Keyword(s):  
Complex Traits ◽  
Quantitative Traits ◽  
Genetic Basis ◽  
Genome Wide Association Study ◽  
Selection Regime ◽  
Genome Wide ◽  
A Genome ◽  
Higher Power ◽  
Powerful Approach ◽  
Next Generation Sequencing Ngs

Abstract Evolve and resequence (E&R) studies are frequently used to dissect the genetic basis of quantitative traits. By subjecting a population to truncating selection for several generations and estimating the allele frequency differences between selected and nonselected populations using next-generation sequencing (NGS), the loci contributing to the selected trait may be identified. The role of different parameters, such as, the population size or the number of replicate populations has been examined in previous works. However, the influence of the selection regime, that is the strength of truncating selection during the experiment, remains little explored. Using whole genome, individual based forward simulations of E&R studies, we found that the power to identify the causative alleles may be maximized by gradually increasing the strength of truncating selection during the experiment. Notably, such an optimal selection regime comes at no or little additional cost in terms of sequencing effort and experimental time. Interestingly, we also found that a selection regime which optimizes the power to identify the causative loci is not necessarily identical to a regime that maximizes the phenotypic response. Finally, our simulations suggest that an E&R study with an optimized selection regime may have a higher power to identify the genetic basis of quantitative traits than a genome-wide association study, highlighting that E&R is a powerful approach for finding the loci underlying complex traits.

scholarly journals Genetic architecture of natural variation in visual senescence in Drosophila

2016 ◽  
Vol 113 (43) ◽  
pp. E6620-E6629 ◽  
Author(s):  
Mary Anna Carbone ◽  
Akihiko Yamamoto ◽  
Wen Huang ◽  
Rachel A. Lyman ◽  
Tess Brune Meadors ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Life Span ◽  
Candidate Genes ◽  
Natural Variation ◽  
Genetic Basis ◽  
Nervous System Development ◽  
Interindividual Variation ◽  
Human Populations ◽  
Age Dependent

Senescence, i.e., functional decline with age, is a major determinant of health span in a rapidly aging population, but the genetic basis of interindividual variation in senescence remains largely unknown. Visual decline and age-related eye disorders are common manifestations of senescence, but disentangling age-dependent visual decline in human populations is challenging due to inability to control genetic background and variation in histories of environmental exposures. We assessed the genetic basis of natural variation in visual senescence by measuring age-dependent decline in phototaxis using Drosophila melanogaster as a genetic model system. We quantified phototaxis at 1, 2, and 4 wk of age in the sequenced, inbred lines of the Drosophila melanogaster Genetic Reference Panel (DGRP) and found an average decline in phototaxis with age. We observed significant genetic variation for phototaxis at each age and significant genetic variation in senescence of phototaxis that is only partly correlated with phototaxis. Genome-wide association analyses in the DGRP and a DGRP-derived outbred, advanced intercross population identified candidate genes and genetic networks associated with eye and nervous system development and function, including seven genes with human orthologs previously associated with eye diseases. Ninety percent of candidate genes were functionally validated with targeted RNAi-mediated suppression of gene expression. Absence of candidate genes previously implicated with longevity indicates physiological systems may undergo senescence independent of organismal life span. Furthermore, we show that genes that shape early developmental processes also contribute to senescence, demonstrating that senescence is part of a genetic continuum that acts throughout the life span.

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