Microevolution Lecture Outline

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Questions and Answers

What is defined as the smallest unit that can evolve, consisting of organisms that can interbreed with fertile offspring?

Population (correct)

Gene pool

Microevolution

Species

Which term describes the genetic exchange between populations that can lead to reduced differences?

Genetic drift

Microevolution

Gene flow (correct)

Fitness

What contributes to a change in allele frequencies in a population over generations?

Hardy-Weinberg equilibrium

Microevolution (correct)

Gene stability

Species diversity

What mechanism of microevolution is illustrated by a windstorm eliminating a group of light green trees?

Genetic drift Signup and view all the answers

What type of mutation involves the random change in genes?

Spontaneous mutation Signup and view all the answers

Which of the following reflects the frequency of the homozygous recessive genotype in the Hardy-Weinberg equation?

q^2 Signup and view all the answers

What represents the contribution an individual makes to the gene pool compared to others in the population?

Relative fitness Signup and view all the answers

Which process can lead to variation in alleles through the exchange of genes during reproduction?

Gene flow Signup and view all the answers

What is a primary factor contributing to genetic drift?

Chance events Signup and view all the answers

How does the bottleneck effect differ from the founder effect in terms of genetic variation?

Bottleneck reduces genetic variation, while founder effect also reduces it Signup and view all the answers

What type of natural selection occurs when a population shifts towards one extreme phenotype?

Directional selection Signup and view all the answers

In natural selection, what is meant by 'fitness'?

The overall contribution an individual makes to the gene pool Signup and view all the answers

What outcome of natural selection is characterized by two extreme phenotypes being favored over the average phenotype?

Disruptive selection Signup and view all the answers

Why might organisms that reproduce more successfully have greater fitness?

They manage to survive and reproduce more effectively Signup and view all the answers

What distinguishes relative fitness from fitness?

Relative fitness compares an individual’s fitness to others Signup and view all the answers

Which of the following is an example of diversifying selection?

A population of fish shows variation in both size and color extremes Signup and view all the answers

Study Notes

Key Definitions

Population: The smallest evolutionary unit, comprised of organisms in the same location capable of interbreeding.
Species: A group of organisms sharing the same name and characteristics.
Gene Pool: The aggregate of genes present in a population.
Microevolution: The gradual change in allele frequencies within a population over time.
Genetic Drift: Random changes in the gene pool of small populations, not influenced by natural selection.
Gene Flow: The transfer of genetic material between populations, reducing genetic differences.
Fitness: The degree to which an individual contributes genes to the next generation relative to others.
Relative Fitness: The comparison of the reproductive success of a genotype against others in the population.

Variation in Alleles

Sexual Reproduction: Introduces variation through crossing over during meiosis.
Mutation: Random alterations in DNA that generate new alleles.

Hardy-Weinberg Equilibrium

p: Represents the frequency of the dominant allele.
p²: Frequency of the homozygous dominant genotype.
q: Represents the frequency of the recessive allele.
q²: Frequency of the homozygous recessive genotype.
2pq: Frequency of the heterozygous genotype.
Example Calculation: For purple flowers (p=0.84), white flowers (q=0.16). Calculation results show that total genotype frequencies sum to 1.

Mechanisms of Microevolution

Genetic Drift: Random events that rearrange allele frequencies; for example, a windstorm eliminates light green trees.
Gene Flow: Exchange of genes between populations, such as the migration of Europeans mixing with Native American gene pools.
Natural Selection: Adaptations occur through traits conferring survival advantages; exemplified by stick bugs evolving camouflage.

Contrast in Mechanisms

Genetic Drift vs. Gene Flow: Drift results from random chance while flow involves specific gene transfers.
Bottleneck Effect: Loss of genetic variation due to population size reduction from disasters.
Founder Effect: Genetic variation diminishes as a small group colonizes a new area.

Outcomes of Natural Selection

Directional Selection: Shift toward a specific trait in a population, e.g., longer beak sizes in birds due to available food.
Diversifying Selection: Favors extreme phenotypes; e.g., small and large seeds available leading to larger and smaller birds thriving.
Stabilizing Selection: Average phenotypes dominate; e.g., medium-sized seeds leading to medium-sized birds being most successful.

Role of Fitness in Evolution

Higher fitness correlates with greater genetic contribution to succeeding generations, driving evolutionary adaptation over time.

Reproductive Success and Fitness

Organisms that reproduce more are deemed 'fitter' as they demonstrate superior survival and reproductive abilities.

Relative Fitness

Focuses on the success of specific genotypes in reproduction compared to others, rather than the fitness of individuals globally.

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Description

This quiz covers key concepts related to microevolution, including definitions of population, species, gene pool, and mechanisms such as genetic drift and gene flow. Understanding these terms is essential for grasping how evolution occurs within smaller scales of time and space. Test your knowledge and see how well you understand the dynamics of microevolution.