wunder beta🦴 Evolution Explained
Descent with modification: how life diversifies through natural selection.
What you’ll learn
- Explain natural selection and where the variation it acts on comes from.Evolution is descent with modification. Natural selection favors heritable traits that improve reproductive success, while mutation and gene recombination supply variation. Drift, gene flow, sexual selection, and speciation also shape the tree of life.
- Summarize the major lines of evidence for evolution.Fossils, homologous and vestigial structures, embryology, and shared DNA all converge on common ancestry. Evolution is observable today in antibiotic resistance and selective breeding, making it a practical, working framework across biology.
Questions this course answers
What did Darwin mean by 'descent with modification'?
Descent with modification describes how populations change over generations, with all species branching from common ancestors.
In evolutionary terms, 'fitness' primarily means:
Fitness refers to how successfully an organism survives and reproduces in its environment, not to strength.
What is the ultimate source of new genetic variation?
New heritable variation arises from mutations in DNA, along with reshuffling during sexual reproduction, providing the raw material for selection.
Why are homologous structures evidence for evolution?
Homologous structures share the same basic anatomy inherited from a common ancestor, even when used differently.
What does shared use of the same genetic code across life suggest?
Nearly all life uses the same genetic code, consistent with descent from a common ancestor.
Which is an example of evolution observable within human timescales?
Bacteria can evolve antibiotic resistance within years, a directly observable case of natural selection.
Grounded in trusted sources
- Charles Darwin, 'On the Origin of Species' (1859)
- National Academy of Sciences, 'Science and Creationism: Evidence Supporting Biological Evolution' (NCBI Bookshelf, NBK230201)
- National Geographic Education, 'Natural Selection' (education.nationalgeographic.org)
- Encyclopaedia Britannica, 'What Darwin Got Right (and Wrong) About Evolution' (britannica.com)
- Biology LibreTexts, 'Evidence for Evolution' (bio.libretexts.org)
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