Biology Chapter 17 Flashcards

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.

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.