Population and Environmental Genetics

What is a gene pool?

The sum of the genetic information from individuals in a population.

What is the source of genetic variation in populations?

Mutations, genetic recombination, and gene flow.

What does the Hardy-Weinberg law describe?

The relationship between allele frequencies and genotype frequencies in a population.

What are the major factors that contribute to changes in allele frequencies?

Natural selection, genetic drift, mutation, and migration.

How do mutations affect allele frequencies?

Mutations create new alleles, contributing to genetic variation in the gene pool.

What is nonrandom mating?

Mating that occurs based on specific traits, affecting allele and genotype frequencies.

Define species according to the biological species concept.

A group of organisms that can interbreed and produce fertile offspring.

What are the two major types of speciation?

Allopatric speciation and sympatric speciation.

What mechanisms contribute to speciation?

Geographic isolation, reproductive isolation, and genetic divergence.

What is reproductive isolation?

Barriers that prevent different species from interbreeding.

How is evolutionary history inferred through genetic analysis?

By comparing genetic similarities and differences among species.

What is genotypic frequency?

The proportion of a particular genotype within a population.

What is allelic frequency?

The proportion of a particular allele within a population.

What does the Hardy-Weinberg equation represent?

p² + 2pq + q² = 1, where p and q are the frequencies of two alleles.

What are the assumptions of the Hardy-Weinberg law?

No selection, mutation, migration, infinite population size, and random mating.

What does it mean if a population is in Hardy-Weinberg equilibrium?

Allele and genotype frequencies remain constant from one generation to the next.

How can you calculate allele frequencies from genotypic frequencies?

Using the formula p = frequency of dominant allele and q = frequency of recessive allele.

What is the significance of the CCR5Δ32 allele?

It conveys resistance to HIV infection.

How do you test for Hardy-Weinberg equilibrium?

Compare observed genotype frequencies with expected frequencies calculated from allele frequencies.

What happens to allele frequencies in a population that evolves?

Allele frequencies change due to factors like selection, drift, or mutation.

What is the relationship between genotypic frequencies and allele frequencies?

As one allele frequency increases, the other typically decreases, affecting heterozygote frequencies.

How many genetic combinations are possible in the ABO blood group system?

Six genetic combinations leading to four possible phenotypes.

What is the frequency of the recessive homozygous genotype in a population?

Calculated as q² in the Hardy-Weinberg equation.

What does p + q = 1 represent?

The total frequency of all alleles in a population must equal 1.

What is the expected frequency of heterozygotes in a population at Hardy-Weinberg equilibrium?

Calculated as 2pq in the Hardy-Weinberg equation.

What is the effect of genetic drift on small populations?

It can lead to significant changes in allele frequencies due to random sampling effects.

What is the impact of migration on allele frequencies?

It can introduce new alleles or change frequencies of existing alleles in a population.

What is natural selection?

A mechanism where individuals with favorable phenotypic variations have higher reproductive success.

How is an organism's fitness defined?

Fitness (w) is the relative reproductive success of a genotype.

What are the types of selection in evolution?

Directional, stabilizing, and disruptive selection.

What is mutation in the context of allele frequency change?

The creation of new alleles that occurs randomly and can change allele frequencies.

What is gene flow?

The movement of individuals between populations that reduces genetic differences.

What is genetic drift?

Random fluctuations in allele frequencies due to chance events, particularly in small populations.

What is the founder effect?

When a new population arises from a small number of individuals, leading to reduced genetic variation.

What is a genetic bottleneck?

A drastic reduction in population size that leads to a loss of genetic diversity.

What is positive assortative mating?

A type of nonrandom mating where like mates with like.

What is inbreeding depression?

The decrease in heterozygotes and potential unmasking of deleterious alleles due to mating between related individuals.

What defines a species according to the biological species concept?

A group of individuals that can interbreed but are reproductively isolated from other groups.

What is allopatric speciation?

Speciation that occurs when a geographic barrier prevents gene flow between populations.

What is sympatric speciation?

Speciation that occurs within a population due to reproductive isolating mechanisms arising without geographic barriers.

What is polyploidy?

A special case of sympatric speciation where an organism has more than two complete sets of chromosomes.

What are phylogenetic trees?

Visual representations of speciation that track evolutionary paths of species.

What is the first step in creating phylogenetic trees?

Obtain gene or genome sequences from multiple species.

What is the role of bioinformatics software in phylogenetic analysis?

To align gene sequences and identify closely related species for divergence point analysis.

What is the significance of reproductive isolation in speciation?

It prevents gene flow between populations, leading to the formation of new species.

What can result from inbreeding over many generations in some species?

It can lead to no harmful effects as deleterious alleles are weeded out over time.

What is the impact of inbreeding on child mortality in humans?

Higher inbreeding depression is associated with increased child mortality and congenital anomalies.

What is the effect of directional selection?

It promotes one specific phenotype, making it more prominent in the population.

What is stabilizing selection?

Selection that favors intermediate phenotypes over extremes.

What is disruptive selection?

Selection that favors both extreme phenotypes at the ends of the spectrum.

How can mutation rates affect allele frequency changes?

Higher mutation rates may significantly impact allele frequencies in small populations.

What is the effect of migration on genetic variation within populations?

It increases genetic variation by introducing new alleles from other populations.