Biology Chapter 17 Flashcards

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Questions and Answers

What is a gene pool?

A group of organisms that cannot reproduce

The total number of alleles in a population

Combined genetic information of all the members of a particular population (correct)

A single gene

What is a single gene trait?

A trait controlled by a single gene that has two alleles.

Define allele frequency.

In a population, the number of times an allele appears.

What is a polygenic trait?

A trait controlled by two or more genes; shows a wide variety of phenotypes. Signup and view all the answers

What is directional selection?

When individuals at one end of the curve have higher fitness than individuals in the middle or at the other end. Signup and view all the answers

Define stabilizing selection.

Natural selection that favors intermediate variants by acting against extreme phenotypes. Signup and view all the answers

What is disruptive selection?

Natural selection that favors individuals with either extreme of a trait; tends to eliminate intermediate phenotypes. Signup and view all the answers

What is genetic drift?

Random change in allele frequencies that occurs in small populations. Signup and view all the answers

Define the bottleneck effect.

Genetic drift resulting from a drastic reduction in population size. Signup and view all the answers

What is the founder effect?

Change in allele frequencies as a result of the migration of a small group of a population. Signup and view all the answers

What does genetic equilibrium mean?

A situation in which allele frequencies remain constant. Signup and view all the answers

What is the Hardy-Weinberg principle?

Principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change. Signup and view all the answers

Define sexual selection.

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates. Signup and view all the answers

What is species?

A group of organisms so similar to one another that they can breed and produce fertile offspring. Signup and view all the answers

Define speciation.

The creation of a new species. Signup and view all the answers

What is reproductive isolation?

Condition in which a reproductive barrier keeps two species from interbreeding. Signup and view all the answers

What is behavioral isolation?

Type of reproductive isolation in which two organisms have different mating rituals that prevent them from interbreeding. Signup and view all the answers

Define geographical isolation.

Type of reproductive isolation in which two different species live in different habitats. Signup and view all the answers

What is temporal isolation?

Form of reproductive isolation in which two populations reproduce at different times. Signup and view all the answers

What is a molecular clock?

Model that uses DNA comparisons to estimate the length of time that two species have been evolving independently. Signup and view all the answers

Study Notes

Genetics Concepts

Gene Pool: Represents the aggregate genetic information of all individuals within a specific population.
Single Gene Trait: A trait influenced by a single gene and its two alleles, leading to distinct phenotypic expressions.

Allele Frequencies and Traits

Allele Frequency: Reflects how often a particular allele appears within a population's gene pool.
Polygenic Trait: Traits governed by two or more genes, resulting in a continuum of phenotypes.

Natural Selection Types

Directional Selection: Occurs when individuals at one extreme of a trait distribution exhibit greater fitness, promoting that extreme trait.
Stabilizing Selection: Favors the average phenotype, enhancing intermediate traits, while reducing variations from extremes.
Disruptive Selection: Encourages extremes of a trait, leading to the decline of intermediate phenotypes in the population.

Population Genetics Mechanisms

Genetic Drift: A random alteration in allele frequencies that has a significant impact on small populations.
Bottleneck Effect: A specific type of genetic drift occurring when a population’s size is sharply reduced, affecting genetic diversity.
Founder Effect: Changes in allele frequencies originating from a small group’s migration and establishment in a new location.

Equilibrium and Evolution Principles

Genetic Equilibrium: A state where allele frequencies remain stable over time, indicating no evolutionary change.
Hardy-Weinberg Principle: Asserts that allele frequencies in a population will remain unchanged unless influenced by external factors.

Reproductive Isolation and Speciation

Sexual Selection: A natural selection variant that favors individuals with particular inherited traits, enhancing mating success.
Species: Defined as a cohesive group of organisms capable of interbreeding and producing viable offspring.
Speciation: The evolutionary process giving rise to new species.

Types of Reproductive Isolation

Reproductive Isolation: A condition preventing interbreeding between species due to various barriers.
Behavioral Isolation: A reproductive barrier where differing mating rituals keep species from mating.
Geographical Isolation: Occurs when species inhabit different environments, preventing interaction and breeding.
Temporal Isolation: Differentiation occurs when two populations reproduce at distinct times, inhibiting interbreeding.

Evolutionary Tools

Molecular Clock: A method utilizing DNA sequence comparisons to gauge the duration of evolutionary divergence between species.

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Description

Test your knowledge with these flashcards covering key concepts from Chapter 17 of Biology. Topics include gene pools, single gene traits, allele frequency, and polygenic traits. Perfect for students looking to reinforce their understanding of genetics.