Evolution explains how populations of living things change over generations. This lesson traces key ideas that preceded Darwin and Wallace, then introduces natural selection as a mechanism for evolutionary change.
Ideas about whether species change have a long history. The Greek philosopher Plato emphasized that species were fixed and unchanging, while other ancient thinkers entertained evolutionary ideas. In the eighteenth century, Georges-Louis Leclerc, Comte de Buffon, revived discussion of animal change and noted that different regions could have distinct plants and animals even when their environments were similar. Some naturalists also accepted that species could become extinct.
All flashcards
What is natural selection?
Differences in reproductive success cause heritable traits that improve survival or reproduction in a particular environment to become more common over generations.
How do mutation and sexual reproduction contribute to genetic diversity?
Mutation creates new alleles; sexual reproduction reshuffles existing alleles into new combinations.
What makes a trait an adaptation?
An adaptation is a heritable trait that improves survival or reproduction in a particular environment; its benefit can depend on environmental conditions.
What are homologous structures?
Structures with similar underlying anatomy because they were inherited from a common ancestor, even if their forms or functions differ.
What can biogeography reveal about evolution?
Geographic distributions can reflect evolutionary history, isolation, and the movement of tectonic plates.
Quiz questions
In science, what is a theory?Answer: A broad explanation supported by extensive evidence and testing.
What does it mean to say that populations, rather than individuals, evolve?Answer: A population’s genetic composition changes across generations.
Which question is not answered by evolutionary theory?Answer: How the first life originated.
Why are insect and bat wings examples of analogous structures?Answer: They serve similar functions but evolved independently from different ancestral structures.
During unusually rainy conditions on Daphne Major, what food availability favored small-billed medium ground finches?Answer: Small, soft seeds were abundant while large, hard seeds became scarce.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.