Genetic Fitness and Allele Frequencies

The video tutorial discusses allele frequencies and the processes affecting them, focusing on the concept of fitness. It introduces relative fitness and selection coefficients, explaining how these factors influence genotype proportions over generations. The persistence of deleterious alleles, despite selection pressures, is also explored, highlighting the roles of heterozygotes and mutations.

What assumption is made about genotypes in the initial discussion of allele frequencies?

• Allele frequencies are constant over time.

• Genotypes do not affect allele frequencies.

• Some genotypes are more fit than others.

• All genotypes are equally fit.

How is relative fitness defined?

• As the mutation rate of a genotype.

• As the absolute number of offspring produced by a genotype.

• As the likelihood of a genotype contributing alleles to the next generation.

• As the total number of alleles in a population.

What does the selection coefficient represent?

• The total number of alleles in a population.

• The mutation rate of a genotype.

• The disadvantage of one genotype compared to another.

• The absolute fitness of a genotype.

What happens to the frequency of less fit genotypes over time?

• It increases rapidly.

• It fluctuates randomly.

• It remains constant.

• It decreases and approaches zero.

Why do deleterious alleles persist in populations?

• They are always beneficial.

• They are present in heterozygotes who have no fitness disadvantage.

• They do not affect fitness at all.

• They are constantly being eliminated.

What role do heterozygotes play in the persistence of deleterious alleles?

• They have a fitness disadvantage.

• They eliminate deleterious alleles.

• They carry deleterious alleles without a fitness disadvantage.

• They increase the frequency of deleterious alleles.

What is one reason the change in allele frequency is slow when the recessive allele is rare?

• Mutation rates are high.

• The recessive allele is always beneficial.

• Selection acts only on homozygotes.

• The recessive allele is dominant.

What is the fitness of a heterozygous carrier in a disease like cystic fibrosis?

• 0.04

• 0.5

• 0.96

• 1.0

How do mutations contribute to the persistence of deleterious alleles?

• They have no effect on allele frequency.

• They increase the fitness of all genotypes.

• They introduce new deleterious alleles.

• They eliminate deleterious alleles.

What is the next topic to be discussed after the role of mutation?

• The effect of environmental changes.

• The role of natural selection.

• The balance between mutation and selection.

• The impact of genetic drift.