Microevolution and Population Genetics

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Questions and Answers

Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?

Population size is finite (correct)

No mutations occurring

Population closed to migration

All genotypes are free of selection

What is the term for the sum of all alleles at all gene loci in all individuals in a population?

Gene pool (correct)

Gene frequency

Genotype frequency

Allele frequency

Which of the following is a source of new alleles?

Genetic drift

Natural selection

Gene flow

Mutation (correct)

What is the term for the process by which allele frequencies change from generation to generation?

Evolution (C) Signup and view all the answers

What mathematical model is used to describe the conditions necessary for genetic equilibrium?

The Hardy-Weinberg principle (C) Signup and view all the answers

What is the term for the different versions of a gene?

Alleles (A) Signup and view all the answers

What method was used to detect the presence and size of various proteins?

Gel electrophoresis (B) Signup and view all the answers

What is the term for the process by which existing alleles are rearranged into new combinations?

Recombination (D) Signup and view all the answers

What is a null hypothesis?

A prediction that a particular factor has no effect (A) Signup and view all the answers

Which of the following is NOT a source of genetic variation?

Hardy-Weinberg equilibrium (A) Signup and view all the answers

What is the main effect of gene flow on allele frequencies?

Gene flow can introduce new alleles into a population, changing allele frequencies. (A) Signup and view all the answers

Which of the following factors is primarily associated with the founder effect?

The establishment of a new population by a small number of individuals. (D) Signup and view all the answers

How does genetic drift differ from gene flow?

Genetic drift is a random process, while gene flow is a directed process. (A) Signup and view all the answers

What is the primary reason why genetic drift typically leads to a decrease in genetic diversity in smaller populations?

Random fluctuations in allele frequencies are more pronounced in smaller populations. (D) Signup and view all the answers

Which of the following statements accurately describes the role of mutations in evolution?

Mutations are the primary source of new genetic variation. (D) Signup and view all the answers

How does genetic recombination during meiosis differ from mutation?

Genetic recombination shuffles existing alleles, while mutation introduces new alleles. (D) Signup and view all the answers

For a mutation to have an evolutionary impact on a population, where must it occur?

In the cells that produce gametes (germ-line cells). (D) Signup and view all the answers

Which of the following is NOT commonly considered a factor that can cause mutations?

Changes in environmental temperature. (D) Signup and view all the answers

What type of variation is described as a difference in features between individuals?

Phenotypic variation (D) Signup and view all the answers

How can we differentiate between genetic and environmental factors contributing to phenotypic variation?

Conducting controlled experiments (D) Signup and view all the answers

Which of the following scenarios exemplifies qualitative variation?

Blood type differences within a human population (C) Signup and view all the answers

What does a low, broad curve on a graph of quantitative variation suggest about the population?

There is a lot of variation in the trait among individuals (D) Signup and view all the answers

What is phenotypic polymorphism, and how is its frequency determined?

The existence of discrete variants of a character within a population, calculated by determining the frequency of each trait (D) Signup and view all the answers

Which of these are examples of balancing selection?

Heterozygote advantage (A), Frequency-dependent selection (B) Signup and view all the answers

What is the primary mechanism by which recessive alleles are protected from complete elimination?

Heterozygote advantage (C) Signup and view all the answers

Which of the following scenarios is NOT a condition for maintaining balancing selection?

A single allele consistently having the highest fitness in all environments (B) Signup and view all the answers

What is the main difference between heterozygote advantage and frequency-dependent selection?

Heterozygote advantage relies on differences in fitness between heterozygotes and homozygotes, while frequency-dependent selection relies on the frequency of the allele in the population (C) Signup and view all the answers

In which evolutionary process is the fitness advantage of a phenotype dependent on its rarity in the population?

Frequency-dependent selection (A) Signup and view all the answers

Which type of natural selection favors individuals with extreme phenotypes over intermediate phenotypes?

Disruptive selection (C) Signup and view all the answers

Study Notes

Microevolution: Changes Within Populations

Species within a population may look similar but are not identical
Phenotypic variation is differences in features
Phenotypic variation can be caused by genetic differences between individuals or environmental factors
Scientists can experimentally determine causes (e.g., soil acidity affects hydrangea flower color)

Microevolution and Genetic Makeup

Microevolution examines changes in the genetic makeup (genotype) of populations over time
Quantitative variation: Individuals differ incrementally (e.g., toe length, hair count)
- A broad, low curve indicates high variation among individuals
- A high, narrow curve indicates low variation among individuals
Qualitative variation: Exists in distinct states, lacking intermediate forms (e.g., blood types, snow goose feathers)
Polymorphism: Existence of multiple discrete variants of a character
- Described quantitatively by calculating trait frequencies

Population Genetics

Gene pool: The sum of all alleles at all gene loci in a population
Population genetics focuses on genetic variation within a population and how it changes over time due to evolution
Evolutionary changes can be caused by four distinct processes

The Hardy-Weinberg Principle

A null hypothesis that defines a non-evolving population
Conditions for genetic equilibrium:
- No mutations
- No migration
- Large population size
- No natural selection
- Random mating

Research Methods Using the Hardy-Weinberg Principle

Example research approach using allele (CR, CW) and genotype frequencies in parent and offspring generations
Methods to assess allele and genotype frequencies
Applying the Hardy-Weinberg equation (p² + 2pq + q² = 1) to determine genotype frequencies in offspring

Gene Flow

Movement of organisms or gametes between populations
Introduces new alleles, altering existing allele and genotype frequencies
Violates the Hardy-Weinberg equilibrium assumption of closed populations

Genetic Drift

Random changes in allele frequencies within a population
More prominent in small populations
Leads to reduced genetic diversity

Mutations

DNA sequence alterations
Sources include radiation, errors in DNA copying, and movement of transposable elements
Can be neutral, harmful, or beneficial
Mutations are random and spontaneous events

Natural Selection

Favors traits that enhance survival and reproduction
Three main types:
- Directional selection: shifts the mean phenotype
- Stabilizing selection: favors intermediate phenotypes
- Disruptive selection: favors extreme phenotypes

Inbreeding Depression / Sexual Selection

Inbreeding: Mating between genetically related individuals
Results in increased proportion of homozygous genotypes and lower fitness
Sexual selection: Favors traits that increase mating success
Intrasexual and intersexual selection

Balancing Selection

Maintains multiple alleles in a population
Driven by heterozygote advantage or varied environmental pressures.

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Description

Explore the fascinating concepts of microevolution and the genetic variations within populations. This quiz delves into phenotypic and genotypic differences, the role of environmental factors, and how scientists study these changes. Test your understanding of polymorphism and quantitative vs qualitative variation.