scholarly journals The genetic basis of size in pet dogs: The study of quantitative genetic variation in an undergraduate laboratory practical

2018 ◽  
Vol 46 (6) ◽  
pp. 623-629
Author(s):  
Craig Wilding
Keyword(s):  
Genetic Variation ◽  
Genetic Basis ◽  
Pet Dogs ◽  
Quantitative Genetic ◽  
Undergraduate Laboratory

Maintenance of Quantitative Genetic Variation

2018 ◽  
Author(s):  
Bruce Walsh ◽  
Michael Lynch
Keyword(s):  
Genetic Variation ◽  
Quantitative Genetics ◽  
Stabilizing Selection ◽  
Quantitative Genetic ◽  
Wide Range

One of the major unresolved issues in quantitative genetics is what accounts for the amount of standing genetic variation in traits. A wide range of models, all reviewed in this chapter, have been proposed, but none fit the data, either giving too much variation or too little apparent stabilizing selection.

scholarly journals UNEQUAL CROSSING OVER AT THE rRNA TANDON AS A SOURCE OF QUANTITATIVE GENETIC VARIATION IN DROSOPHILA

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 727-742 ◽  
Author(s):  
R Frankham ◽  
D A Briscoe ◽  
R K Nurthen
Keyword(s):  
Genetic Variation ◽  
Selection Response ◽  
Crossing Over ◽  
Wild Type ◽  
X Chromosomes ◽  
Unequal Crossing Over ◽  
Quantitative Genetic ◽  
Y Chromosomes ◽  
Homozygous Line ◽  
Minimum Estimate

ABSTRACT Abdominal bristle selection lines (three high and three low) and controls were founded from a marked homozygous line to measure the contribution of sex-linked "mutations" to selection response. Two of the low lines exhibited a period of rapid response to selection in females, but not in males. There were corresponding changes in female variance, in heritabilities in females, in the sex ratio (a deficiency of females) and in fitness, as well as the appearance of a mutant phenotype in females of one line. All of these changes were due to bb alleles (partial deficiencies for the rRNA tandon) in the X chromosomes of these lines, while the Y chromosomes remained wild-type bb+. We argue that the bb alleles arose by unequal crossing over in the rRNA tandon.—A prediction of this hypothesis is that further changes can occur in the rRNA tandon as selection is continued. This has now been shown to occur.—Our minimum estimate of the rate of occurrence of changes at the rRNA tandon is 3 × 10-4. As this is substantially higher than conventional mutation rates, the questions of the mechanisms and rates of origin of new quantitative genetic variation require careful re-examination.

scholarly journals The Molecular Basis of Quantitative Genetic Variation in Central and Secondary Metabolism in Arabidopsis

Genetics ◽  
1998 ◽  
Vol 149 (2) ◽  
pp. 739-747 ◽  
Author(s):  
Thomas Mitchell-Olds ◽  
Deana Pedersen
Keyword(s):  
Enzyme Activity ◽  
Genetic Variation ◽  
Secondary Metabolism ◽  
Genetic Correlations ◽  
Theoretical Models ◽  
Model Systems ◽  
Activity Levels ◽  
Significant Qtls ◽  
Cis Acting ◽  
Quantitative Genetic

Abstract To find the genes controlling quantitative variation, we need model systems where functional information on physiology, development, and gene regulation can guide evolutionary inferences. We mapped quantitative trait loci (QTLs) influencing quantitative levels of enzyme activity in primary and secondary metabolism in Arabidopsis. All 10 enzymes showed highly significant quantitative genetic variation. Strong positive genetic correlations were found among activity levels of 5 glycolytic enzymes, PGI, PGM, GPD, FBP, and G6P, suggesting that enzymes with closely related metabolic functions are coregulated. Significant QTLs were found influencing activity of most enzymes. Some enzyme activity QTLs mapped very close to known enzyme-encoding loci (e.g., hexokinase, PGI, and PGM). A hexokinase QTL is attributable to cis-acting regulatory variation at the AtHXK1 locus or a closely linked regulatory locus, rather than polypeptide sequence differences. We also found a QTL on chromosome IV that may be a joint regulator of GPD, PGI, and G6P activity. In addition, a QTL affecting PGM activity maps within 700 kb of the PGM-encoding locus. This QTL is predicted to alter starch biosynthesis by 3.4%, corresponding with theoretical models, suggesting that QTLs reflect pleiotropic effects of mutant alleles.

scholarly journals The genomics of adaptation

2012 ◽  
Vol 279 (1749) ◽  
pp. 5024-5028 ◽  
Author(s):  
Jacek Radwan ◽  
Wiesław Babik
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Royal Society ◽  
Genetic Basis ◽  
Genomic Data ◽  
Evolutionary Change ◽  
Introductory Article ◽  
Technological Advances ◽  
A Genome ◽  
Genome Level

The amount and nature of genetic variation available to natural selection affect the rate, course and outcome of evolution. Consequently, the study of the genetic basis of adaptive evolutionary change has occupied biologists for decades, but progress has been hampered by the lack of resolution and the absence of a genome-level perspective. Technological advances in recent years should now allow us to answer many long-standing questions about the nature of adaptation. The data gathered so far are beginning to challenge some widespread views of the way in which natural selection operates at the genomic level. Papers in this Special Feature of Proceedings of the Royal Society B illustrate various aspects of the broad field of adaptation genomics. This introductory article sets up a context and, on the basis of a few selected examples, discusses how genomic data can advance our understanding of the process of adaptation.

Environmental stress and quantitative genetic variation in butterfly wing characteristics

2008 ◽  
Vol 23 (3) ◽  
pp. 473-485 ◽  
Author(s):  
W. Talloen ◽  
S. Van Dongen ◽  
H. Van Dyck ◽  
L. Lens
Keyword(s):  
Genetic Variation ◽  
Environmental Stress ◽  
Butterfly Wing ◽  
Quantitative Genetic

scholarly journals Unique Genomic and Phenotypic Responses to Extreme and Variable pH Conditions in Purple Urchin Larvae

2020 ◽  
Vol 60 (2) ◽  
pp. 318-331
Author(s):  
April D Garrett ◽  
Reid S Brennan ◽  
Anya L Steinhart ◽  
Aubrey M Pelletier ◽  
Melissa H Pespeni
Keyword(s):  
Genetic Variation ◽  
Allele Frequency ◽  
Sea Urchin ◽  
Genetic Basis ◽  
Adaptive Genetic Variation ◽  
Protein Coding ◽  
Purple Sea Urchin ◽  
Ph Conditions ◽  
Frequency Changes ◽  
Genetic Responses

Synopsis Environmental variation experienced by a species across space and time can promote the maintenance of genetic diversity that may be adaptive in future global change conditions. Selection experiments have shown that purple sea urchin, Strongylocentrotus purpuratus, populations have adaptive genetic variation for surviving pH conditions at the “edge” (pH 7.5) of conditions experienced in nature. However, little is known about whether populations have genetic variation for surviving low-pH events beyond those currently experienced in nature or how variation in pH conditions affects organismal and genetic responses. Here, we quantified survival, growth, and allele frequency shifts in experimentally selected developing purple sea urchin larvae in static and variable conditions at three pH levels: pH 8.1 (control), pH 7.5 (edge-of-range), and pH 7.0 (extreme). Variable treatments recovered body size relative to static treatments, but resulted in higher mortality, suggesting a potential tradeoff between survival and growth under pH stress. However, within each pH level, allele frequency changes were overlapping between static and variable conditions, suggesting a shared genetic basis underlying survival to mean pH regardless of variability. In contrast, genetic responses to pH 7.5 (edge) versus pH 7.0 (extreme) conditions were distinct, indicating a unique genetic basis of survival. In addition, loci under selection were more likely to be in exonic regions than regulatory, indicating that selection targeted protein-coding variation. Loci under selection in variable pH 7.5 conditions, more similar to conditions periodically experienced in nature, performed functions related to lipid biosynthesis and metabolism, while loci under selection in static pH 7.0 conditions performed functions related to transmembrane and mitochondrial processes. While these results are promising in that purple sea urchin populations possess genetic variation for surviving extreme pH conditions not currently experienced in nature, they caution that increased acidification does not result in a linear response but elicits unique physiological stresses and survival mechanisms.

The coevolution of host resistance and parasitoid virulence

Parasitology ◽  
1998 ◽  
Vol 116 (S1) ◽  
pp. S29-S45 ◽  
Author(s):  
A. R. Kraaijeveld ◽  
J. J. M. Van Alphen ◽  
H. C. J. Godfray
Keyword(s):  
Genetic Variation ◽  
Artificial Selection ◽  
Host Resistance ◽  
Genetic Basis ◽  
Isofemale Line ◽  
Fitness Costs ◽  
Geographical Patterns ◽  
Wide Range ◽  
Great Scope ◽  
Fertile Area

SummaryHost-parasitoid interactions are abundant in nature and offer great scope for the study of coevolution. A particularly fertile area is the interaction between internal feeding parasitoids and their hosts. Hosts have evolved a variety of means of combating parasitoids, in particular cellular encapsulation, while parasitoids have evolved a wide range of countermeasures. Studies of the evolution of host resistance and parasitoid virulence are reviewed, with an emphasis on work involvingDrosophilaand its parasitoids. Genetic variation in both traits has been demonstrated using isofemale line and artificial selection techniques. Recent studies have investigated the fitness costs of maintaining the ability to resist parasitoids, the comparative fitness of flies that have successfully defended themselves against parasitoids, and the degree to which resistance and virulence act against one or more species of host or parasitoid. A number of studies have examined geographical patterns, and sought to look for local adaptation; or have compared the traits across a range of species. Finally, the physiological and genetic basis of change in resistance and virulence is being investigated. While concentrating onDrosophila, the limited amount of work on different systems is reviewed, and other possible areas of coevolution in host-parasitoid interactions are briefly discussed.

Quantitative genetic basis of fatty acid composition in the GIFT strain of Nile tilapia (Oreochromis niloticus) selected for high growth

Aquaculture ◽  
2010 ◽  
Vol 309 (1-4) ◽  
pp. 66-74 ◽  
Author(s):  
Nguyen Hong Nguyen ◽  
Raul W. Ponzoni ◽  
Hoong Yip Yee ◽  
Khairul R. Abu-Bakar ◽  
Azhar Hamzah ◽  
...  
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Genetic Basis ◽  
High Growth ◽  
Quantitative Genetic ◽  
Nile Tilapia Oreochromis Niloticus ◽  
The Gift
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