Population genetics is a branch of genetics that studies population differences. It is part of evolutionary biology, which studies such things as adaptation, population structure, and speciation. Its origins date back to the early 20^th century, and would go on to further our knowledge of evolution.

Population genetics helped with the emergence of modern evolutionary synthesis. Modern evolutionary synthesis was an early 20^th century idea that revolved around Charles Darwin and Gregor Mendel's teachings. It would make evolution biology's focal point, and give the mathematical framework for such

The first step to population genetics was the Hardy-Weinberg principle. The principle provides a solution to how variation occurs in a population through Mendel inheritance. This helped show why some traits were inherited while others were not (Dominant vs Recessive traits).

The founders of population genetics were two scientists, J. B. S. Haldane and Ronald Fisher. Ronald Fisher would lead the charge, writing a series of papers from 1918 to 1930, and then putting it in his book The Genetical Theory of Natural Selection. He would show how continuous variations measured by biometricians could easily show alleles being manipulated by natural selection (survival of the fittest).

J. B. S. Haldane would follow very shortly in 1924, when he began to release his own series of papers. He worked out allele frequency and the mathematics behind changes in genes. Haldane found that genes could change based on a wide variety of conditions, and used statistical analysis to give examples of natural selection in the real world.

This would not be their only contribution to genetics. They would lay down the groundwork for quantitative genetics. Quantitative genetics is a field that relates to population genetics, and revolves around phenotypes (An organism's traits or characteristics).

There are a few approaches that keep population genetics separate from newer ways to model evolution. It has a much larger emphasis on phenomena in genetics, like dominance (Dominant traits vs. recessive traits), epistasis (A gene being dependent on another gene's existence), and genetic combination and how it can break apart how alleles form in non-random ways.

Along with dominance and epistasis, there are two other processes that population genetics revolves around. One of those is natural selection, mentioned before as being survival of the fittest. The final one is mutation, which is when genetic mutation cause new species or variations of a species to be born. This may be caused by adaptation, but it could be caused randomly in the genes.

Population genetics is pushed forward consistently with our need to know what's going on in evolution. Even though it is the Theory of Evolution, it is widely regarded as a scientific fact. Population genetics helps push it forward by listing all the different variations and ways a population or species can evolve, and why they evolved in the first place. With more information, scientists hope to keep pushing evolution forward with advances in population genetics.

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