Evolution of Populations Genetic Variation mutations genetic shuffling
- Slides: 12
Evolution of Populations
Genetic Variation mutations genetic shuffling Natural selection allele frequencies changes evolution
Example Red lizards ◦ more visible to predators less likely to survive and reproduce allele for red coloring become rare Black lizards ◦ absorb more sunlight warm up faster move faster to feed and avoid predators produce more offspring Alleles for black become common
Natural Selection on Polygenic Traits Direction Selection: individuals at one end of the curve have higher fitness ◦ beak size & thickness
Beak Size in Birds
Natural Selection on Polygenic Traits Stabilizing Selection - individuals near the curve’s center have higher fitness ◦ Size of baby at birth
Natural Selection on Polygenic Traits Disruptive Selection - individuals at the upper and lower ends of the curve have higher fitness ◦ Environment with few medium size seeds
Genetic Drift Small population ◦ individuals with a particular allele may leave more descendants by chance ◦ With more chance occurrences ◦ an allele to become common in a population. Founder Effect: allele frequencies change due to a subgroup’s migration
Genetic Drift
Hardy – Weinberg Principle allele frequencies remain constant unless factor(s) change frequencies Requirements of Hardy-Weinberg ◦ ◦ ◦ random mating very large population no movement in or out of the population no mutations no natural selection
Speciation: new species formation Reproductive Isolation: 2 populations cannot interbreed and produce fertile offspring Behavioral Isolation ◦ Different courtship rituals ◦ Different reproductive strategies Geographic Isolation ◦ geographic barriers; rivers, mountains Temporal Isolation ◦ reproduce at different times of the year
- Stabilizing selection human birth weight
- Evolution of populations section 16-1 genes and variation
- Exon shuffling spiegazione
- Oligonucleotide directed mutagenesis
- Caeccum
- Genetic drift
- What is the difference between genetic drift and gene flow
- Genetic drift in small populations
- Chapter 23: the evolution of populations
- Why are populations the smallest unit of evolution
- Section 16-1 genes and variation
- Chapter 16 evolution of populations vocabulary review
- Evolution of populations section 11 review