Questions and Answers
What are the requirements for evolution by natural selection? (Select all that apply)
What is fitness?
The idea that the organisms that best match their environment will have greater survival and reproduction of their alleles.
When does natural selection occur?
When the environment pressures a population so that only some phenotypes survive and reproduce.
What does stabilizing selection result in?
Signup and view all the answers
What does directional selection result in?
Signup and view all the answers
What does disruptive or diversifying selection result in?
Signup and view all the answers
When does balancing selection occur?
Signup and view all the answers
What are two common types of balancing selection? (Select all that apply)
Signup and view all the answers
What is frequency-dependent selection?
Signup and view all the answers
What is heterozygote advantage?
Signup and view all the answers
Does evolution of bigger, sexually reproducing organisms happen on time scales faster than geologic time?
Signup and view all the answers
How does natural selection explain how bacterial populations evolve resistance to antibiotics?
Signup and view all the answers
What conditions lead to evolution by natural selection? (Select all that apply)
Signup and view all the answers
Which of the following statements is/are accurate? (Select all that apply)
Signup and view all the answers
Which statement describes the canary with the greatest biological fitness?
Signup and view all the answers
Study Notes
Requirements for Evolution by Natural Selection
- Population must display VARIABLE traits, meaning there are multiple alleles for a given gene.
- Traits must be HERITABLE, allowing them to be passed from one generation to another.
- A STRUGGLE FOR EXISTENCE exists as more offspring are produced than can survive.
- Individuals with different alleles exhibit VARIED SURVIVAL AND REPRODUCTION rates based on environmental fitness.
Concept of Fitness
- Fitness refers to the ability of organisms that match their environment closely to achieve higher survival rates and reproductive success.
Occurrence of Natural Selection
- Natural selection occurs when environmental pressures favor certain phenotypes, leading to a non-random shift in allele frequencies between generations.
Stabilizing Selection
- Results in a narrower normal distribution by favoring individuals with average phenotypes, allowing them to produce more offspring than those at extremes.
Directional Selection
- Shifts normal distribution toward one phenotypic extreme, favoring individuals at that end to have more offspring than those at the opposite extreme.
Disruptive or Diversifying Selection
- Leads to the division of a normal distribution into two separate distributions, as individuals with extreme phenotypes outperform those with intermediate phenotypes.
Balancing Selection
- Occurs when multiple phenotypes or alleles are maintained in a population without a single phenotype having a consistent advantage.
Types of Balancing Selection
- Commonly includes frequency-dependent selection and heterozygote advantage.
Frequency-Dependent Selection
- The fitness of a phenotype or allele is influenced by its frequency within the population.
Heterozygote Advantage
- The heterozygote possesses a combined phenotype from both alleles, granting it a higher fitness compared to either homozygote.
Evolutionary Time Scale
- Evolution of larger sexually reproducing organisms can occur faster than geological time, exemplified by rock pocket mice adapting to different environments.
Bacterial Evolution and Antibiotic Resistance
- Evolution of bacteria's antibiotic resistance is driven by rare mutant bacteria surviving antibiotic treatments, rather than adaptations being passed from individual bacteria.
Conditions for Evolution by Natural Selection
- Key conditions include competition for limited resources and heritable variation in the population. Unlimited resources do not support natural selection.
Accuracy of Statements on Natural Selection
- Natural selection acts on pre-existing variation in populations. Evolution by natural selection results solely from selection on heritable traits.
Biological Fitness of Canaries
- The canary with the highest biological fitness is one that produces the most surviving offspring, emphasizing the importance of both longevity and reproductive success.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on the key requirements for evolution by natural selection. This flashcard quiz covers essential concepts like variability, heritability, and the struggle for existence. Enhance your understanding of evolutionary biology through these engaging questions.