unit 1 Flashcards
(16 cards)
What is the definition of evolution in terms of allele frequency?
Evolution is the change in allele frequencies in a population over time.
What are Darwin’s four postulates of evolution by natural selection?
1) Variation exists among individuals. 2) Some traits are inherited. 3) More offspring are produced than can survive. 4) Variation affects survival and reproduction.
What is genetic variation?
Differences in alleles of genes found within individuals in a population.
What is population genetics?
The study of the properties of genes in a population and how they change over time.
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1, where p = frequency of dominant allele, q = frequency of recessive allele.
What five conditions must be met for Hardy-Weinberg equilibrium?
1) Large population, 2) No mutation, 3) Random mating, 4) No gene flow, 5) No selection.
What are the five agents of evolutionary change?
Mutation, gene flow, nonrandom mating, genetic drift, natural selection.
What is the founder effect?
When a small group forms a new population, leading to loss of genetic variation.
What is the bottleneck effect?
A sudden reduction in population size due to a natural event, causing reduced genetic variation.
Define fitness in evolutionary biology.
The ability of an organism to survive and reproduce in its environment.
What is sexual selection?
A form of natural selection where traits increase mating success.
What’s the difference between intrasexual and intersexual selection?
Intrasexual: competition within one sex. Intersexual: mate choice by the opposite sex.
What is frequency-dependent selection?
Fitness of a phenotype depends on its frequency in the population.
What is the heterozygote advantage?
Heterozygous individuals have higher fitness than either homozygote (e.g., sickle cell and malaria resistance).
What are the three types of natural selection?
1) Stabilizing – favors intermediate traits, 2) Directional – favors one extreme, 3) Disruptive – favors both extremes.
What is the role of pleiotropy and epistasis in evolution?
They affect how genes respond to selection; pleiotropy: one gene affects multiple traits, epistasis: one gene’s effect depends on another.
