Learn about population genetics and how genetic variation changes in populations over time. Explore Hardy-Weinberg equilibrium, genetic drift, selection, and gene flow with interactive examples and visualizations.
Population genetics is the study of genetic variation within populations and how this variation changes over time. It combines Mendelian inheritance with mathematical models to explain evolutionary processes. The field examines allele frequencies, genetic drift, natural selection, gene flow, and mutation as mechanisms of evolution.
Mathematical model describing allele frequencies in an ideal population with no evolutionary forces acting upon it.
Random changes in allele frequencies due to chance events, more significant in smaller populations.
Differential survival and reproduction of individuals due to differences in phenotype.
Simulate allele frequencies in an ideal population under Hardy-Weinberg equilibrium.
Initial Allele Frequencies:
A (p): 0.50 | a (q): 0.50
Expected Genotype Frequencies:
AA: 0.25 | Aa: 0.50 | aa: 0.25
Actual Genotype Frequencies:
AA: 0.25 | Aa: 0.50 | aa: 0.25
Visualize how random events affect allele frequencies in populations of different sizes.
Allele Frequency:
A: 0.50 | a: 0.50
Fixation Probability:
A: 0.50 | a: 0.50
Time to Fixation:
N/A
Genotype Frequencies:
AA: 0.36 (p²)
Aa: 0.48 (2pq)
aa: 0.16 (q²)
Allele Frequencies:
A (p): 0.60
a (q): 0.40
Problem: In a population of 1000 individuals, 360 have the genotype AA, 480 have Aa, and 160 have aa. Is this population in Hardy-Weinberg equilibrium?
Solution:
Observed frequencies:
AA: 360/1000 = 0.36
Aa: 480/1000 = 0.48
aa: 160/1000 = 0.16
Allele frequencies:
p = (2×360 + 480) / (2×1000) = 0.6
q = 1 - p = 0.4
Expected frequencies under H-W:
AA: p² = 0.36 ✓
Aa: 2pq = 0.48 ✓
aa: q² = 0.16 ✓
Since observed = expected, the population is in Hardy-Weinberg equilibrium.
Problem: A population of 10 individuals has an allele frequency of 0.3 for allele A. After a genetic drift event, what are the possible new allele frequencies?
Solution:
In a population of 10 individuals, there are 20 alleles total.
Initially: 0.3 × 20 = 6 A alleles
After drift, the number of A alleles could range from 0 to 20.
Possible frequencies: 0/20=0, 1/20=0.05, 2/20=0.1, ..., 20/20=1.0
Genetic drift can cause significant changes in small populations.
Problem: In a population, individuals with genotype aa have a 20% lower fitness than AA and Aa individuals. Calculate the selection coefficient and predict the change in allele frequency over time.
Solution:
Selection coefficient (s) = 1 - relative fitness
If AA and Aa have fitness = 1, then aa has fitness = 0.8
s = 1 - 0.8 = 0.2
Over time, the frequency of allele a will decrease due to selection pressure.
Population Genetics: Studies genetic variation within populations and how it changes over time.
Classical Genetics: Focuses on inheritance patterns of traits in individuals and families.
Population genetics examines broader evolutionary patterns, while classical genetics looks at specific inheritance mechanisms.
Population Genetics: Mathematical framework for understanding genetic changes in populations.
Evolutionary Biology: Broader field studying evolution at all levels (molecular, organismal, ecological).
Population genetics provides the mathematical foundation for many concepts in evolutionary biology.
Population Genetics: Focuses on genetic variation at the population level.
Molecular Genetics: Studies genes and their functions at the molecular level.
Population genetics uses molecular data but focuses on patterns across populations rather than molecular mechanisms.
Population Genetics: Studies genetic variation and its change over time.
Quantitative Genetics: Focuses on inheritance of complex traits influenced by multiple genes.
Both fields overlap significantly, but quantitative genetics emphasizes statistical analysis of complex traits.
Save your simulation parameters and results for later analysis.
Load previously saved simulation data to continue your analysis.