A Method for the Direct Study of Natural Selection

1. Decisive experiments on selection of mutants of Drosophila melanogaster can be carried out under natural conditions in Britain where this species is not indigenous. 2. This communication records an experiment in which a balanced population containing 25% ebony mutants was released in South Devon. 3. The frequency of the genotype among the descendants was estimated after a period equivalent to six discrete generations, by testing trapped flies, most of which were wild type in appearance, for heterozygosis. 4. The frequency estimated was very close to what would be deduced on the assumption that elimination of the recessive type before maturity was complete.

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THE EFFECTS OF NATURAL SELECTION OF LINKAGE DISEQUILIBRIUM AND RELATIVE FITNESS IN EXPERIMENTAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽

10.1093/genetics/48.9.1201 ◽

1963 ◽

Vol 48 (9) ◽

pp. 1201-1216

Author(s):

Grace Bert Cannon

Keyword(s):

Drosophila Melanogaster ◽

Linkage Disequilibrium ◽

Natural Selection ◽

Relative Fitness ◽

Experimental Populations ◽

Selection Of

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Natural Selection of Mutants of Vesicular Stomatitis Virus by Cultured Cells of Drosophila melanogaster

Journal of General Virology ◽

10.1099/0022-1317-20-3-341 ◽

1973 ◽

Vol 20 (3) ◽

pp. 341-351 ◽

Cited By ~ 37

Author(s):

J. A. Mudd ◽

R. W. Leavitt ◽

D. T. Kingsbury ◽

J. J. Holland

Keyword(s):

Drosophila Melanogaster ◽

Natural Selection ◽

Vesicular Stomatitis Virus ◽

Cultured Cells ◽

Vesicular Stomatitis ◽

Selection Of

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Interplay between protein stability, binding to ACE2 and escape from neutralizing antibodies determines the natural selection of SARS-CoV-2 receptor binding domain variants

10.1101/2021.05.23.445348 ◽

2021 ◽

Author(s):

Vaibhav Upadhyay ◽

Alexandra Lucas ◽

Sudipta Panja ◽

Krishna Mallela

Keyword(s):

Natural Selection ◽

Receptor Binding ◽

Binding Domain ◽

Wild Type Virus ◽

Titration Calorimetry ◽

Human Antibody ◽

Receptor Binding Domain ◽

Wild Type ◽

Similar Affinity ◽

Selection Of

Emergence of new SARS-CoV-2 variants has raised concerns at the effectiveness of vaccines and antibody therapeutics developed against the unmutated wild-type virus. It is thus important to understand the emergence of mutants from an evolutionary viewpoint to be able to devise effective countermeasures against new variants. We examined the effect of 12 most commonly occurring mutations in the receptor binding domain (RBD) on its expression, stability, activity, and antibody escape potential- some of the factors that may influence the natural selection of mutants. Recombinant proteins were expressed in human cells. Stability was measured using thermal denaturation melts. Activity and antibody escape potential were measured using isothermal titration calorimetry in terms of binding of RBD variants to ACE2 and to a neutralizing human antibody CC12.1, respectively. Our results show that variants differ in their expression levels, suggesting that mutations can impact the availability of proteins for virus assembly. All variants have similar or higher stability than the wild-type, implying that increased RBD stability might be another important factor in virus evolution. In terms of ACE2 binding, when compared to the wild-type, only 3 out of 7 expressed variants show stronger affinity, 2 have similar affinity, whereas the other 2 have weaker affinity, indicating that increased affinity towards ACE2 is an important but not the sole factor in the natural selection of variants. In terms of CC12.1 binding, when compared to the wild-type, 4 out of 7 variants have weaker affinity, 2 have a similar affinity, and 1 variant has a stronger affinity. Taken together, these results indicate that multiple factors contribute towards the natural selection of variants, and all of these factors have to be considered in order to understand the natural selection of SARS-CoV-2 variants. In addition, since not all variants can escape a given neutralizing antibody, antibodies to treat new variants can be chosen based on the specific mutations in that particular variant.

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Studies in Artificial Selection of Quantitative Characters I. Selection for Abdominal Bristles in Drosophila Melanogaster

Australian Journal of Biological Sciences ◽

10.1071/bi9630490 ◽

1963 ◽

Vol 16 (2) ◽

pp. 490 ◽

Cited By ~ 11

Author(s):

BL Sheldon

Keyword(s):

Drosophila Melanogaster ◽

Artificial Selection ◽

Mass Selection ◽

Wild Type ◽

Diallel Crosses ◽

Laboratory Stock ◽

Quantitative Characters ◽

Selection For ◽

Selection Of

Genetic and phenotypic parameters for number of abdominal bristles were estimated from diallel crosses in a wild-type laboratory stock, Oregon-Reo Two replicate mass selection lines in both high and low directions were developed and run for over 30 generations. The same parameters were estimated from dianel ~rosses at intervals during the experiment.

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On the evolution of dominance, over-dominance and balanced polymorphism

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1967.0062 ◽

1967 ◽

Vol 168 (1011) ◽

pp. 216-228 ◽

Cited By ~ 4

Keyword(s):

Natural Selection ◽

Recurrence Relations ◽

Genetic Variance ◽

Sickle Cell Trait ◽

Theoretical Models ◽

Wild Type ◽

Balanced Polymorphism ◽

The Difference ◽

Set Up ◽

Selection Of

Recurrence relations are derived for the natural selection of a selective coefficient that is subject to additive genetic variations. Mathematical models are set up of the natural selection of the selective coefficient of the heterozygote. A general computer model of genetical populations is described and populations are set up to simulate genetic variation of the heterozygote. The theoretical models are applied to the spread of a gene under natural selection. If the heterozygote is initially intermediate between the two homozygotes, the evolution of semi-dominance, dominance or over-dominance depends on the genetic variance in fitness. Over-dominance evolves if the standard deviation in fitness due to genetic causes is about 0.7 times the difference between the initial heterozygote and homozygote fitnesses. The heterozygote will then continue to increase in fitness until the characters that determine the fitness are at their optimum values. Thus the polymorphism tends to become more stable. The fitness of the heterozygote of a recurrent mutation will also be raised by natural selection. Dominance still evolves though it takes many thousands of generations. Eventually over-dominance, too, evolves and a balanced polymorphism is thus established. This will explain many polymorphisms, like the sickle cell trait in man, which have a highly deleterious homozygote. Selection slowly raises the fitness of the heterozygote to an optimum above that of the wild-type.

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