The logarithm of fitness as a function of the number of deleterious mutations. Synergistic epistasis is represented by the red line - each subsequent deleterious mutation has a larger proportionate effect on the organism's fitness. Antagonistic epistasis is in blue. The black line shows the non-epistatic case, where fitness is the product of the contributions from each of its loci.
Haldane in 1914
Drosophila melanogaster
Marcello Siniscalco (standing) and Haldane in Andhra Pradesh, India, 1964
Gene flow is the transfer of alleles from one population to another population through immigration of individuals. In this example, one of the birds from population A immigrates to population B, which has fewer of the dominant alleles, and through mating incorporates its alleles into the other population.
J.B.S. Haldane Avenue in Kolkata, the busy connecting road from Eastern Metropolitan Bypass to Park Circus area containing Science City
The Great Wall of China is an obstacle to gene flow of some terrestrial species.
A Low cartoon featuring Haldane – "Prophesies for 1949"
Current tree of life showing vertical and horizontal gene transfers.
Lysenko speaking at the Kremlin in 1935. Behind him are (left to right) Stanislav Kosior, Anastas Mikoyan, Andrei Andreev and Joseph Stalin.
Oxford University Museum of Natural History display dedicated to Haldane and his reply when asked to comment on the mind of the Creator.

Its primary founders were Sewall Wright, J. B. S. Haldane and Ronald Fisher, who also laid the foundations for the related discipline of quantitative genetics.

- Population genetics

Subsequent works established a unification of Mendelian genetics and Darwinian evolution by natural selection whilst laying the groundwork for modern evolutionary synthesis and thus helped to create population genetics.

- J. B. S. Haldane
The logarithm of fitness as a function of the number of deleterious mutations. Synergistic epistasis is represented by the red line - each subsequent deleterious mutation has a larger proportionate effect on the organism's fitness. Antagonistic epistasis is in blue. The black line shows the non-epistatic case, where fitness is the product of the contributions from each of its loci.

5 related topics

Alpha

Fisher in 1913

Ronald Fisher

British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic.

British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic.

Fisher in 1913
As a child
Inverforth House, North End Way NW3, where Fisher lived from 1896 to 1904
On graduating from Cambridge University, 1912
The peacock tail in flight, the classic example of a Fisherian runaway
Rothamsted Research
Memorial plaque over his remains, lectern-side aisle of St Peter's Cathedral, Adelaide
Stained glass window (now removed) in the dining hall of Caius College, in Cambridge, commemorating Ronald Fisher and representing a Latin square, discussed by him in The Design of Experiments
As a steward at the First International Eugenics Conference, 1912

Together with J. B. S. Haldane and Sewall Wright, Fisher is known as one of the three principal founders of population genetics.

Gregor Mendel, the Moravian Augustinian monk who founded the modern science of genetics

Mendelian inheritance

Type of biological inheritance that follows the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and popularized by William Bateson.

Type of biological inheritance that follows the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and popularized by William Bateson.

Gregor Mendel, the Moravian Augustinian monk who founded the modern science of genetics
Characteristics Mendel used in his experiments
P-Generation and F1-Generation: The dominant allele for purple-red flower hides the phenotypic effect of the recessive allele for white flowers. F2-Generation: The recessive trait from the P-Generation phenotypically reappears in the individuals that are homozygous with the recessive genetic trait.
Myosotis: Colour and distribution of colours are inherited independently.
F1 generation: All individuals have the same genotype and same phenotype expressing the dominant trait ( red ).
F2 generation: The phenotypes in the second generation show a 3 : 1 ratio.
In the genotype 25 % are homozygous with the dominant trait, 50 % are heterozygous genetic carriers of the recessive trait, 25 % are homozygous with the recessive genetic trait and expressing the recessive character.
In Mirabilis jalapa and Antirrhinum majus are examples for intermediate inheritance. As seen in the F1-generation, heterozygous plants have " light pink " flowers—a mix of " red " and "white". The F2-generation shows a 1:2:1 ratio of red : light pink : white
A Punnett square for one of Mendel's pea plant experiments – self-fertilization of the F1 generation
Segregation and independent assortment are consistent with the chromosome theory of inheritance.
When the parents are homozygous for two different genetic traits (llSS and LL sP sP), their children in the F1 generation are heterozygous at both loci and only show the dominant phenotypes (Ll S sP). P-Generation: Each parent possesses one dominant and one recessive trait purebred (homozygous). In this example, solid coat color is indicated by S (dominant), Piebald spotting by sP (recessive), while fur length is indicated by L (short, dominant) or l (long, recessive). All individuals are equal in genotype and phenotype. In the F2 generation all combinations of coat color and fur length occur: 9 are short haired with solid colour, 3 are short haired with spotting, 3 are long haired with solid colour and 1 is long haired with spotting. The traits are inherited independently, so that new combinations can occur. Average number ratio of phenotypes 9:3:3:1
For example 3 pairs of homologous chromosomes allow 8 possible combinations, all equally likely to move into the gamete during meiosis. This is the main reason for independent assortment. The equation to determine the number of possible combinations given the number of homologous pairs = 2x (x = number of homologous pairs)

Ronald Fisher combined these ideas with the theory of natural selection in his 1930 book The Genetical Theory of Natural Selection, putting evolution onto a mathematical footing and forming the basis for population genetics within the modern evolutionary synthesis.

Mendel's findings allowed scientists such as Fisher and J.B.S. Haldane to predict the expression of traits on the basis of mathematical probabilities.

Several major ideas about evolution came together in the population genetics of the early 20th century to form the modern synthesis, including genetic variation, natural selection, and particulate (Mendelian) inheritance. This ended the eclipse of Darwinism and supplanted a variety of non-Darwinian theories of evolution.

Modern synthesis (20th century)

The early 20th-century synthesis reconciling Charles Darwin's theory of evolution and Gregor Mendel's ideas on heredity in a joint mathematical framework.

The early 20th-century synthesis reconciling Charles Darwin's theory of evolution and Gregor Mendel's ideas on heredity in a joint mathematical framework.

Several major ideas about evolution came together in the population genetics of the early 20th century to form the modern synthesis, including genetic variation, natural selection, and particulate (Mendelian) inheritance. This ended the eclipse of Darwinism and supplanted a variety of non-Darwinian theories of evolution.
Darwin's pangenesis theory. Every part of the body emits tiny gemmules which migrate to the gonads and contribute to the next generation via the fertilised egg. Changes to the body during an organism's life would be inherited, as in Lamarckism.
Blending inheritance, implied by pangenesis, causes the averaging out of every characteristic, which as the engineer Fleeming Jenkin pointed out, would make evolution by natural selection impossible.
August Weismann's germ plasm theory. The hereditary material, the germplasm, is confined to the gonads and the gametes. Somatic cells (of the body) develop afresh in each generation from the germplasm.
William Bateson championed Mendelism.
Karl Pearson led the biometric school.
Sewall Wright introduced the idea of a fitness landscape with local optima.
Drosophila pseudoobscura, the fruit fly which served as Theodosius Dobzhansky's model organism
E. B. Ford studied polymorphism in the scarlet tiger moth for many years.
Julian Huxley presented a serious but popularising version of the theory in his 1942 book Evolution: The Modern Synthesis.
Ernst Mayr argued that geographic isolation was needed to provide sufficient reproductive isolation for new species to form.
George Gaylord Simpson argued against the naive view that evolution such as of the horse took place in a "straight-line". He noted that any chosen line is one path in a complex branching tree, natural selection having no imposed direction.
Speciation via polyploidy: a diploid cell may fail to separate during meiosis, producing diploid gametes which self-fertilize to produce a fertile tetraploid zygote that cannot interbreed with its parent species.
Ant societies have evolved elaborate caste structures, widely different in size and function.
Evolutionary developmental biology has formed a synthesis of evolutionary and developmental biology, discovering deep homology between the embryogenesis of such different animals as insects and vertebrates.
A 21st century tree of life showing horizontal gene transfers among prokaryotes and the saltational endosymbiosis events that created the eukaryotes, neither fitting into the 20th century's modern synthesis
Inputs to the modern synthesis, with other topics (inverted colours) such as developmental biology that were not joined with evolutionary biology until the turn of the 21st century

The 19th-century ideas of natural selection and Mendelian genetics were put together with population genetics, early in the twentieth century.

His efforts stimulated the biologist J. B. S. Haldane to push for the axiomatisation of biology, and by influencing thinkers such as Huxley, helped to bring about the modern synthesis.

Figure A: Line graph example. The birth rate in Brazil (2010–2016); Figure B: Bar chart example. The birth rate in Brazil for the December months from 2010 to 2016; Figure C: Example of Box Plot: number of glycines in the proteome of eight different organisms (A-H); Figure D: Example of a scatter plot.

Biostatistics

Biostatistics (also known as biometry) are the development and application of statistical methods to a wide range of topics in biology.

Biostatistics (also known as biometry) are the development and application of statistical methods to a wide range of topics in biology.

Figure A: Line graph example. The birth rate in Brazil (2010–2016); Figure B: Bar chart example. The birth rate in Brazil for the December months from 2010 to 2016; Figure C: Example of Box Plot: number of glycines in the proteome of eight different organisms (A-H); Figure D: Example of a scatter plot.
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Scatter diagram that demonstrates the Pearson correlation for different values of ρ.

The three leading figures in the establishment of population genetics and this synthesis all relied on statistics and developed its use in biology.

J. B. S. Haldane's book, The Causes of Evolution, reestablished natural selection as the premier mechanism of evolution by explaining it in terms of the mathematical consequences of Mendelian genetics. Also developed the theory of primordial soup.

Biston betularia f. typica, the white-bodied peppered moth.

Peppered moth evolution

Evolutionary instance of directional colour change in the moth population as a consequence of air pollution during the Industrial Revolution.

Evolutionary instance of directional colour change in the moth population as a consequence of air pollution during the Industrial Revolution.

Biston betularia f. typica, the white-bodied peppered moth.
Biston betularia f. carbonaria, the black-bodied peppered moth.
Typica and carbonaria morphs on the same tree. The light-coloured typica (below the bark's scar) is nearly invisible on this pollution-free tree, camouflaging it from predators.
Creationists have disputed the occurrence or significance of the melanic carbonaria morph's increase in frequency.

In 1924, J.B.S. Haldane calculated, using a simple general selection model, the selective advantage necessary for the recorded natural evolution of peppered moths, based on the assumption that in 1848 the frequency of dark-coloured moths was 2%, and by 1895 it was 95%.

Haldane's statistical analysis of selection for the melanic variant in peppered moths became a well known part of his effort to demonstrate that mathematical models that combined natural selection with Mendelian genetics could explain evolution – an effort that played a key role in the foundation of the discipline of population genetics, and the beginnings of the modern synthesis of evolutionary theory with genetics.