(3)Genetic Variation and Selection Mechanisms

Flashcards covering key concepts, definitions, and examples from a lecture on genetic variation, selection mechanisms, and evolutionary principles.

What is the difference between locus selection and selection on quantitative traits?

Locus selection focuses on specific genes, while selection on quantitative traits involves traits influenced by multiple genes.

What are the definitions of Homozygote advantage and Heterozygote advantage?

Homozygote advantage occurs when individuals with homozygous genotypes have higher fitness, while Heterozygote advantage occurs when heterozygous individuals have higher fitness.

What does 'mean fitness' refer to in the context of selection?

Mean fitness is the average reproductive success of individuals within a population.

What is meant by the term 'selection coefficient'?

The selection coefficient quantifies the fitness disadvantage of a particular genotype relative to others.

How do directional selection, stabilizing selection, and diversifying selection differ?

Directional selection favors one extreme phenotype, stabilizing selection favors average phenotypes, and diversifying selection favors extreme phenotypes at both ends.

What is the significance of sickle cell anemia's high frequency in certain regions?

Sickle cell anemia persists due to heterozygote advantage in malaria-prone areas where carriers are more resistant to malaria.

What is mutation-selection balance?

Mutation-selection balance is the equilibrium where the rate of new mutations is balanced by the rate of selection against deleterious alleles.

Will dominant deleterious loci be at a higher or lower frequency than recessives due to mutation-selection balance? Why?

Dominant deleterious loci will generally be at a lower frequency because they are selected against more strongly than recessive alleles.

What does phenotypic plasticity refer to?

Phenotypic plasticity is the ability of a single genotype to produce different phenotypes in response to varying environmental conditions.

How does genetic drift affect population genetic diversity?

Genetic drift leads to the random loss of alleles, reducing genetic diversity and potentially leading to fixation of one allele.

Define 'founder effects' and their impact on genetic diversity.

Founder effects occur when a small number of individuals establish a new population, leading to reduced genetic diversity compared to the original population.

What distinguishes substitution rate from mutation rate?

Substitution rate measures how quickly alleles replace one another in a population, while mutation rate refers to the frequency of new mutations arising.