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Population genetics studies genetic changes in groups that can breed together and produce fertile offspring, defined specifically for genetics versus other disciplines. Key variations include interpopulation variation (differences between populations, e.g., skin color in China vs. Sweden) and intrapopulation variation (changes within a population over time). Allele frequency is essential, calculated as the number of a specific allele in a population divided by total alleles. For example, in a population of cats with alleles coding for black and tabby coats, frequencies are calculated based on the total number of alleles.

Definitions:

• Population Genetics: Study of allele frequencies and their changes in populations.

• Gene Pool: The total collection of alleles in a population at a given time.

• Evolution: Change in allele frequency over time, with microevolution as small changes and macroevolution involving significant changes, potentially leading to new species.

Various research methods are utilized in population genetics, classified from descriptive observational studies to case-control studies, randomized controlled trials, and synthetic studies that compile data from multiple studies. This week, we will focus on cross-sectional and case-control studies to explore these concepts further.