microevolution (population genetics)

what is the only source of new alleles in a population

mutation

what causes mutations?

changes in nucleotide sequences (can also involve chromosome structure)

mutations are

heritable

how do prokaryotes (like bacteria) contribute to genetic variation?

• binary fission (asexual reproduction)

• high mutation rate

• rapid reproduction rate

how does sexual reproduction contribute to genetic variation?

it creates unique combinations of alleles through recombination from both parents

what does natural selection act on - phenotype or genotype?

its acts on phenotype and indirectly acts on genotype

what is a Mendelian trait

a trait controlled by one gene, with phenotypes that are “on” or “off” (e.g. widows peak)

what are traits that show gradation

traits controlled by 2 or more genes, like skin color, that show a wide range of phenotypes

Hardy Weinberg equation

Described a population that is not evolving

p + q = 1 → allele frequency

p^2 + 2pq + q^2 = 1 → genotype frequency

p^2 = homo dominant genotype

2pq = heterozygous genotype

q^2 = homo recessive genotype

p^2 + 2pq = dominant phenotype

q^2 = recessive phenotype

Criteria for Hardy Weinberg equation

• No mutations

• Random mating

• No natural selection

• A very large population

• No gene flow between populations

If any of these are not true → alleles frequencies are changing!

what is the source of genetic variation

mutationw

what violate Hardy-Weinberg equilibrium?

mutation

which process involves movement of alleles between populations?

gene flow

A population is small and affected by a natural disaster, causing a drastic reduction in allele frequencies. This is an example of:

Bottleneck effect

In the Hardy-Weinberg equation, what does 2pq represent?

Heterozygous genotype

Which of the following correctly compares non-random mating and sexual selection?

Non-random mating is proximity-based, sexual selection is trait-based

Which of the following is true about natural selection?

Maintains favorable traits in a population

Which scenario best illustrates the founder effect?

A few birds colonize a new island, bringing only some alleles

Which Hardy-Weinberg component represents the frequency of the recessive phenotype?

q²

Which of the following is a random change in allele frequency due to chance?

Genetic drift

What best describes non-random mating?

Mating influenced by proximity or phenotype

Which process causes adaptation through differential survival across environments?

Natural selection

What is a key feature of genetic drift?

Random loss of alleles in small populations

Which mechanism involves the movement of alleles between populations?

Gene flow

Which of the following is likely to reduce genetic differences between populations?

Gene flow

Why does genetic drift violate Hardy-Weinberg equilibrium?

It occurs in small populations where chance events change allele frequencies

What is the relationship between sexual selection and non-random mating?

Sexual selection is a type of non-random mating based on traits

What does natural selection require to act upon in a population?

Existing variation in traits

Which of the following does not necessarily increase the size of a gene pool?

natural selection

Which mechanism is adaptive and maintains favorable genotypes?

Natural selection

What happens during a bottleneck effect?

Population size is drastically reduced, limiting future genetic variation

What best describes the outcome of gene flow between two populations?

Reduction in genetic differences between populations

Which is true about mutation?

It is a random change in DNA that may introduce new alleles

How does non-random mating contribute to evolution?

It affects who mates based on traits, which can change genotype frequencies

Which of the following is not an example of gene flow?

A random mutation in one population

Which evolutionary mechanism works regardless of whether alleles are favorable?

Genetic drift

What would best describe the role of proximity in mating?

It’s a form of non-random mating where nearby individuals are more likely to mate

Which mechanism directly involves survival and reproduction of the fittest individuals?

Natural selection

According to Ernst Mayr’s Biological Species Concept (BSC), what defines a species?

Ability to interbreed and produce viable, fertile offspring in nature

What keeps genotypes similar between populations in the BSC?

Gene flow

What is a key requirement of species under the BSC?

Must be reproductively isolated from other groups

Why is the BSC not useful for fossil species?

you cannot observe reproductive behavior in fossils