Mechanisms of Evolution and Natural Selection

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Questions and Answers

What effect describes the formation of new populations by a few individuals?

Genetic bottleneck

Founder effect (correct)

Trait selection

Natural selection

Which scenario best illustrates the bottleneck effect?

A natural disaster causing a large population to shrink rapidly (correct)

Small group of founders creating a new community

A diverse population adapting to a new environment

A few individuals migrating to an isolated island

What is a major consequence of genetic drift?

Increased genetic diversity in a population

Consistent preservation of all alleles

Direct adaptation to the environment

Random changes in allele frequencies (correct)

Which of the following populations would likely experience a more significant impact from genetic drift?

A small isolated community with 30 individuals Signup and view all the answers

What distinguishes the process of evolution from natural selection?

Evolution is the change in populations over time. Signup and view all the answers

What is the result of natural selection over many generations?

Allele frequencies change significantly in the population Signup and view all the answers

Which of the following best describes stabilizing selection?

Selection favors average traits, reducing variation Signup and view all the answers

Which factor does NOT contribute to changes in the gene pool of a population?

Age of the individuals Signup and view all the answers

The Pennsylvania Amish community is an example of which evolutionary concept?

Founder Effect Signup and view all the answers

How do mutations contribute to evolution?

They introduce new alleles, leading to variation. Signup and view all the answers

What effect does non-random mating typically have on a population?

Increased chance of harmful alleles being expressed. Signup and view all the answers

Which mode of natural selection leads to the emergence of two distinct phenotypes?

Disruptive selection Signup and view all the answers

What is indicated by a change in allele frequency within a population?

Microevolution has occurred. Signup and view all the answers

Which statement accurately describes sexual selection?

It can lead to sexual dimorphism. Signup and view all the answers

Which of the following correctly describes genetic drift?

It causes changes in allele frequencies due to chance events. Signup and view all the answers

What role does gene flow play in populations?

It involves the movement of alleles through migration. Signup and view all the answers

Study Notes

Mechanisms of Evolution and Their Effect on Populations

Evolution is possible due to genetic variation within populations.
Sexual reproduction creates new combinations of alleles in offspring.
Each new generation consists of genetically unique individuals.
Mutations occur randomly.

Natural Selection

Natural selection acts on heritable traits.
It leads to populations better adapted to their environments.
Natural selection favors individuals with genes for herbicide resistance, enabling them to reproduce and pass on these genes.
Individuals do not evolve, but populations do.
Traits affect an individual's survival and reproduction chances within a particular environment; the impacts of natural selection become apparent when tracking population changes over time.

Factors Changing Allele Frequencies in Populations

Allele frequencies reflect the number of copies of an allele compared to the total number of alleles in a population.
A change in allele frequency indicates microevolution.
Microevolution refers to small events leading to evolution within a population.

Gene Pool

The gene pool comprises all the alleles within a population.
Geneticists focus on the gene pool when studying evolution at a population level.
Factors that change the gene pool include mutations, gene flow, non-random mating, genetic drift, and natural selection.

Types of Genetic Drift

Founder Effect: New populations formed by few individuals; carry only some alleles from the original population, limiting diversity.
Bottleneck Effect: A drastic event reduces a large population's size; survivors have limited allele diversity.

Types of Natural Selection

Stabilizing Selection: Favors intermediate phenotypes and acts against extreme phenotypes (e.g., birth mass).
Directional Selection: Favors phenotypes at one extreme (e.g., beak size).
Disruptive Selection: Favors both extremes of a trait's range (e.g., different colored rabbits).
Microevolution only pertains to changes in a population versus individuals.

Summary of Microevolution

Natural selection results in adaptation, unlike other evolutionary mechanisms.

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Description

This quiz explores the mechanisms of evolution, focusing on genetic variation, natural selection, and how these factors affect population dynamics. Understand how allele frequencies change over time and the role of sexual reproduction and mutations in creating genetic diversity. Test your knowledge on how natural selection leads to adaptations in populations.