AP Biology Unit 7 Topic 1: Natural and aritificial selection

What to Know

Natural selection depends on environmental conditions and acts on phenotypes, not on what organisms need.
Artificial selection occurs when humans choose which traits are favored for breeding.
Selection can only increase traits that already have heritable variation in a population.
Always connect this topic back to the larger unit: Natural Selection.

Detailed Notes

Natural and aritificial selection belongs to Unit 7: Natural Selection. Selection changes trait frequencies when heritable variation affects survival or reproductive success. Treat the topic as a relationship between structure, process, evidence, and biological function instead of memorizing an isolated definition.

Key relationships: Natural selection depends on environmental conditions and acts on phenotypes, not on what organisms need. Artificial selection occurs when humans choose which traits are favored for breeding. Selection can only increase traits that already have heritable variation in a population.

Model to use: Use a population trait distribution before and after selection to explain how frequency shifts over generations. A clear model should label the parts, show the direction of movement or information flow when relevant, and connect the diagram back to the biological outcome.

AP-style move: Avoid saying individuals evolve; explain how the population's heritable trait frequencies change. Strong answers name the concept, apply it to the scenario, and explain the reasoning in complete sentences.

Key Vocabulary

Natural selection

Differential survival and reproduction caused by heritable variation in a population.

Artificial selection

Human-directed breeding that changes trait frequencies.

Fitness

Relative reproductive success in a particular environment.

Adaptation

A heritable trait that improves reproductive success in a specific environment.

Selection pressure

An environmental factor that affects which phenotypes reproduce more successfully.

Heritable variation

Genetic differences that can be passed from parents to offspring.

Quick Practice

How would you explain Natural and aritificial selection in one or two AP-style sentences?

Name the concept, apply it to a specific example or source, and explain the reasoning that connects the evidence to your answer.

Official Alignment

Reference and Attribution

Biology concept reference: Biology for AP Courses by OpenStax, Rice University. Access for free at OpenStax. Licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License. EduCompanion used this source as a conceptual reference and rewrote the study notes in original wording.