Evolution and Genetics

Exons
- Portions of a gene that are expressed, contrasting with introns which are not expressed.
- Example: Analysis pertains to a gene in Homo sapiens with approximately 6,000 letters sequenced.
Aligning Genes Across Species
- Using the example of a platypus, we can align genes between species to observe genetic relationships.
- Similarities found between human genes and platypus genes indicate a common ancestry, even though significant differences exist overall.
- Comparison shows more genetic similarity between humans and mammals (like the platypus) than with non-mammals (like trees).
Comparative Genomics with Chimpanzees
- Comparing humans with a chimpanzee highlights a dramatic genetic overlap in the same gene, showcasing over 96% genetic similarity.
- Humans share 99.9999% of their DNA with one another, with the small differences defining individual traits.

Understanding Evolution
- Evidence of evolution is not only through genetic similarities but also through simulation of populations.
- Population simulation software is utilized to study the dynamics of allele distribution over time.
Simulation Variables
- Simulated population size examples, typically around 1,000 individuals in the model.
- Two alleles are examined, with associated p (dominant allele) and q (recessive allele) values defined.
- Genotype categories include:
- Homozygous Dominant
- Heterozygous
- Homozygous Recessive
Mechanisms of Change
- Bottleneck Effect: A sudden reduction in population size can lead to genetic drift. Example: simulating a bottleneck that reduces a population from 1,000 to 10.
- Factors affecting allele frequencies in populations include:
- Mutation
- Migration
- Selection Pressure: For example, if the homozygous recessive individuals have only a 50% survival chance, this would influence allele frequency over generations.