scholarly journals Complex constraints on allometry revealed by artificial selection on the wing of Drosophila melanogaster

2015 ◽  
Vol 112 (43) ◽  
pp. 13284-13289 ◽  
Author(s):  
Geir H. Bolstad ◽  
Jason A. Cassara ◽  
Eladio Márquez ◽  
Thomas F. Hansen ◽  
Kim van der Linde ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Allometric Scaling ◽  
Power Laws ◽  
Selection Response ◽  
Wing Shape ◽  
Fundamental Aspect ◽  
Direct Selection ◽  
Evolutionary Potential ◽  
Internal Selection

Precise exponential scaling with size is a fundamental aspect of phenotypic variation. These allometric power laws are often invariant across taxa and have long been hypothesized to reflect developmental constraints. Here we test this hypothesis by investigating the evolutionary potential of an allometric scaling relationship in drosophilid wing shape that is nearly invariant across 111 species separated by at least 50 million years of evolution. In only 26 generations of artificial selection in a population of Drosophila melanogaster, we were able to drive the allometric slope to the outer range of those found among the 111 sampled species. This response was rapidly lost when selection was suspended. Only a small proportion of this reversal could be explained by breakup of linkage disequilibrium, and direct selection on wing shape is also unlikely to explain the reversal, because the more divergent wing shapes produced by selection on the allometric intercept did not revert. We hypothesize that the reversal was instead caused by internal selection arising from pleiotropic links to unknown traits. Our results also suggest that the observed selection response in the allometric slope was due to a component expressed late in larval development and that variation in earlier development did not respond to selection. Together, these results are consistent with a role for pleiotropic constraints in explaining the remarkable evolutionary stability of allometric scaling.

scholarly journals Transposable element-induced response to artificial selection in Drosophila melanogaster: molecular analysis of selection lines.

Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 803-811 ◽  
Author(s):  
A E Shrimpton ◽  
T F Mackay ◽  
A J Brown
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Genetic Variance ◽  
Selection Response ◽  
P Element ◽  
Induced Response ◽  
Phenotypic Variance ◽  
P Elements ◽  
Insertion Sites

Abstract Artificial selection lines for abdominal bristle score of Drosophila melanogaster established from P-M hybrid dysgenic crosses showed increases in selection response, heritability and phenotypic variance compared to similar lines started from nondysgenic crosses. To determine whether this increased genetic variance could be due to enhanced transposition of P elements following the dysgenic cross, the cytological locations (sites) of P elements were determined by in situ hybridization for the whole genome of samples of 20 individuals from the parental P strain, 20 individuals from each of the eight dysgenic selection lines, and ten individuals from each of the eight nondysgenic selection lines. Variation among and within the selection lines and the parental P strain in P element insertion sites was exceptionally high. A total of 601 sites were identified, but there was no difference in total number of sites per line, mean number of sites per individual, mean copy number per individual, or site frequency between dysgenic and nondysgenic selection lines, or between lines selected for high and low bristle score. Transposition following nondysgenic crosses may explain additional observations of accelerated selection responses in nondysgenic selection lines. It was not possible to deduce which, if any, of the several hundred insertions in the dysgenic selection lines were responsible for their extreme bristle phenotypes.

scholarly journals Polygenic mutation in Drosophila melanogaster: the causal relationship of bristle number to fitness.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 861-872 ◽  
Author(s):  
S V Nuzhdin ◽  
J D Fry ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Random Mating ◽  
Direct Selection ◽  
Stabilizing Selection ◽  
Fitness Effects ◽  
Bristle Number ◽  
Mean Fitness ◽  
The Mean ◽  
Average Fitness

Abstract The association between sternopleural and abdominal bristle number and fitness in Drosophila melanogaster was determined for sublines of an initially highly inbred strain that were maintained by divergent artificial selection for 150 generations or by random mating for 180 generations. Replicate selection lines had more extreme bristle numbers than those that were maintained without artificial selection at the same census size for approximately the same number of generations. The average fitness, estimated by a single generation of competition against a compound autosome strain, was 0.17 for lines selected for high and low abdominal bristle numbers and 0.19 for lines selected for high and low sternopleural bristle number. The average fitness of unselected lines, 0.46, was significantly higher than that of the selection lines. The fitnesses and the relationships of bristle number to fitness in progeny of all possible crosses of high x high (H x H), high x low (H x L) and low x low (L x L) selection lines were examined to determine whether the observed intermediate optima were caused by direct stabilizing selection on bristle number or by apparent stabilizing selection mediated through deleterious pleiotropic fitness effects of mutations affecting bristle number. Although bristle number was nearly additive for progeny of H x H, H x L and L x L crosses among sternopleural bristle selection lines, their mean fitnesses were not significantly different from each other, or from the mean fitness of the unselected lines, suggesting partly or completely recessive pleiotropic fitness effects cause apparent stabilizing selection. The average fitness of the progeny of H x H abdominal bristle selection lines was not significantly different from the fitness of unselected lines, but the mean fitness of the progeny of L x L crosses was not significantly different from that of the pure low lines. This is consistent with direct selection against low but not high abdominal bristle number, but the interpretation is confounded by variation in average degree of dominance for fitness (on average recessive in the high abdominal bristle selection lines and additive in the low abdominal bristle selection lines). Neither direct stabilizing selection nor pleiotropy, therefore, can account for all the observations.

scholarly journals Corrigendum to: Consequences of genetic selection for environmental impact traits on economically important traits in dairy cows

2018 ◽  
Vol 58 (10) ◽  
pp. 1966
Author(s):  
Purna Kandel ◽  
Sylvie Vanderick ◽  
Marie-Laure Vanrobays ◽  
Hélène Soyeurt ◽  
Nicolas Gengler
Keyword(s):  
Dairy Cows ◽  
Body Condition Score ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Selection Response ◽  
Direct Selection ◽  
Correlated Response ◽  
Production Traits ◽  
Ch4 Emissions ◽  
Natural Logarithm

Methane (CH4) emission is an important environmental trait in dairy cows. Breeding aiming to mitigate CH4 emissions require the estimation of genetic correlations with other economically important traits and the prediction of their selection response. In this study, test-day CH4 emissions were predicted from milk mid-infrared spectra of Holstein cows. Predicted CH4 emissions (PME) and log-transformed CH4 intensity (LMI) computed as the natural logarithm of PME divided by milk yield (MY). Genetic correlations of PME and LMI with traits used currently were approximated from correlations between estimated breeding values of sires. Values were for PME with MY 0.06, fat yield (FY) 0.09, protein yield (PY) 0.13, fertility 0.17; body condition score (BCS) –0.02; udder health (UDH) 0.22; and longevity 0.22. As expected by its definition, values were negative for LMI with production traits (MY –0.61; FY –0.15 and PY –0.40) and positive with fertility (0.36); BCS (0.20); UDH (0.08) and longevity (0.06). The genetic correlations of 33 type traits with PME ranged from –0.12 to 0.25 and for LMI ranged from –0.22 to 0.18. Without selecting PME and LMI (status quo) the relative genetic change through correlated responses of other traits were in PME by 2% and in LMI by –15%, but only due to the correlated response to MY. Results showed for PME that direct selection of this environmental trait would reduce milk carbon foot print but would also affect negatively fertility. Therefore, more profound changes in current indexes will be required than simply adding environmental traits as these traits also affect the expected progress of other traits.

scholarly journals A SIMULATION STUDY OF TRUNCATION SELECTION FOR A QUANTITATIVE TRAIT OPPOSED BY NATURAL SELECTION

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 989-1000
Author(s):  
Francis Minvielle
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Random Mating ◽  
Selection Response ◽  
Quantitative Character ◽  
Mass Selection ◽  
Frequency Selection ◽  
Selection Experiments ◽  
Selection For ◽  
Selective Process

ABSTRACT A quantitative character controlled at one locus with two alleles was submitted to artificial (mass) selection and to three modes of opposing natural selection (directional selection, overdominance and underdominance) in a large random-mating population. The selection response and the limits of the selective process were studied by deterministic simulation. The lifetime of the process was generally between 20 and 100 generations and did not appear to depend on the mode of natural selection. However, depending on the values of the parameters (initial gene frequency, selection intensity, ratio of the effect of the gene to the environmental standard deviation, fitness values) the following outcomes of selection were observed: fixation of the allele favored by artificial selection, stable nontrivial equilibrium, unstable equilibrium and loss of the allele favored by artificial selection. Finally, the results of the simulation were compared to the results of selection experiments.

scholarly journals PROPERTIES AND EVOLUTIONARY POTENTIAL OF NEWLY INDUCED TANDEM DUPLICATIONS IN DROSOPHILA MELANOGASTER

Genetics ◽  
1982 ◽  
Vol 102 (1) ◽  
pp. 75-89
Author(s):  
Paul A Roberts ◽  
David J Broderick
Keyword(s):  
Drosophila Melanogaster ◽  
Linkage Disequilibrium ◽  
Tandem Duplication ◽  
Polytene Chromosomes ◽  
Primary Source ◽  
Evolutionary Potential ◽  
X Ray ◽  
Fitness Effects ◽  
New Genes ◽  
Tandem Duplications

ABSTRACT Most of some 33 X-ray-induced duplications recovered as Suppressors of Minute loci proved to be direct tandem duplications. When heterozygous, most duplications were crossover suppressors, and duplications of short to moderate size did not reduce the fitness of their bearers. Crossover suppression by tandem duplication may be attributed to intrastrand foldbacks of the type regularly seen in somatic polytene chromosomes. As a consequence, linkage disequilibrium between duplicated elements and normal chromosomes should be more profound than has been supposed. Tandem duplications appear to be predisposed by reason of frequency of generation, crossover suppression and fitness effects to serve as the primary source of new genes.

An Analysis of Polygenes Affecting Wing Shape on Chromosome 2 inDrosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 1045-1057 ◽  
Author(s):  
Kenneth Weber ◽  
Robert Eisman ◽  
Shawn Higgins ◽  
Lisa Morey ◽  
April Patty ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Transposable Element ◽  
Genetic Effects ◽  
Wing Shape ◽  
Pleiotropic Effects ◽  
Phenotypic Variance ◽  
Chromosome 2 ◽  
Additive Effects ◽  
Chromosome Segments ◽  
Small Additive

AbstractGenetic effects on an index of wing shape on chromosome 2 of Drosophila melanogaster were mapped using isogenic recombinants with transposable element markers. At least 10 genes with small additive effects are dispersed evenly along the chromosome. Many interactions exist, with only small net effects in homozygous recombinants and little effect on phenotypic variance. Heterozygous chromosome segments show almost no dominance. Pleiotropic effects on leg shape are only minor. At first view, wing shape genes form a rather homogeneous class, but certain complexities remain unresolved.

Mendelian Executive

2021 ◽  
pp. 1-9
Author(s):  
Daniel A. Levinthal
Keyword(s):  
Rational Choice ◽  
Artificial Selection ◽  
Selection Criteria ◽  
Direct Consequence ◽  
Dynamic Environments ◽  
Differential Selection ◽  
Selection Environment ◽  
Selection Processes ◽  
Internal Selection

A “Mendelian” executive is proposed as an image of strategy-making that lies intermediate between the grand strategist suggested by rational choice approaches and a Darwinian process of random variation and market-based differential selection. The Mendelian executive is capable of intentional design efforts in order to explore possible adjacent strategic spaces. Furthermore, the argument developed here highlights the role of intentionality with respect to selection processes within the organization, and the culling and amplification of strategic initiatives. The firm is viewed as operating an “artificial selection” environment in contrast to selection as the direct consequence of the outcome of competitive processes. Examining the nature of the processes generating these experimental variants and the bases of internal selection, and how these selection criteria may themselves change, is argued to be central to the formation of strategy in dynamic environments.

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