Week 2 Flashcards
Changes in allele frequencies
A shift in how common different alleles are in a population over generations
Non-random mating
When individuals choose mates based on specific traits rather than randomly
Genetic Drift
Random changes in allele frequencies due to chance events
Founder Effect
Genetic drift when a small group starts a new population with limited genetic diversity
When is the founder effect the most common?
- When its undergoing a major shift in its distribution
- When humans move species
- During range shifting due to climate change
Population Bottlenecks
- A sharp reduction in population size, leading to lost genetic diversity
- Population might regrow
What is between-generation sampling error?
Errors that occur between generations when populations are constant in size
Gene flow
The movement of alleles between populations through migration or breeding
What is the relationship between genetic variation and population size?
Larger populations tend to have more genetic variation
Directional Selection
Natural selection that favours one extreme phenotype, shifting traits in a population
Stabilizing Selection
Selection that favours average traits and reduces extremes
Disruptive Selection
Selection that favours extreme traits over the average
Heterozygote advantage
Heterozygotes have higher fitness than homozygotes, often due to disease resistance
Underdominance
- Opposite of heterozygote advantage
- heterozygotes have lower fitness than either homozygote, leading to the disadvantage of mixed alleles
Sexual Selection
When traits that increase an individual’s chances of attracting a mate are favoured
Sexual Dimorphism
Differences in appearance between males and females of the same species
What is the good gene hypothesis?
The idea that females prefer mates with traits signaling good health or strong genes for better offspring
What phenomenons posed problems for evolution and genetics?
- Quantitative traits
- Dominance
What is the equilibrium principle?
Allele frequencies in a population remain constant over time unless influenced by evolutionary forces
4 forces of non-equilibrium
- Genetic Drift
- Nonrandom Mating
- Gene Flow
- Fitness Differences
Nonrandom Mating
Mating where individuals select partners based on specific traits, rather than randomly
Fitness Differences
Variations in survival and reproductive success among individuals due to different traits
The modern synthesis
The integration of Darwin’s theory of evolution with genetics, explaining evolution as changes in allele frequencies over time
Neo-Darwinism
A modern theory combining Darwin’s natural selection with Mendelian genetics, explaining evolution through genetic variation and survival of the fittest
Quantitative Genetics
The study of traits that are controlled by multiple genes, often showing continuous variation in a populatio
Heritability
The proportion of variation in a trait that is due to genetic factors, as opposed to environmental factors in a population
Plasmodium parasites
- Causes malaria
- complex life cycle involving two hosts
How is malaria related to natural selection?
Malaria drives natural selection by favoring genetic traits like sickle cell allele, which provides resistance to the disease in heterozygotes
Sickle-Cell Anaemia
A genetic disorder causing misshapen red blood cells
