Overview
This lecture covers Charles Darwin's theory of evolution by natural selection, the influences on his ideas, evidence for evolution, and key concepts in evolutionary biology.
Darwin and the Voyage of the Beagle
- Charles Darwin was a naturalist who sailed on the HMS Beagle, collecting plant and animal specimens.
- He spent significant time in the Galapagos Islands, observing unique species.
- Darwin's observations contributed to his ideas about evolution and adaptation.
Development of the Theory of Evolution
- Evolution is the concept that species change over time; Darwin did not invent the idea but provided scientific evidence.
- Darwin's major contribution was the mechanism of natural selection to explain evolutionary change.
- He published "On the Origin of Species" in 1859, summarizing his findings and theories.
Natural Selection
- Natural selection is the process where better-adapted individuals survive and reproduce more successfully.
- Textbook definition: differential reproduction under natural conditions.
- "Survival of the fittest" describes individuals best suited to their environment passing on their genes.
Influences on Darwin
- Charles Lyell's studies of fossils and rock layers suggested Earth was much older than 6,000 years.
- Fossils are remains or imprints of living organisms found in sequential rock layers.
- Thomas Malthus wrote about populations growing faster than resources, influencing Darwin's thinking on competition and survival.
Evidence for Evolution
- Fossil records show periods of stability and change, suggesting a long history of life on Earth.
- Comparative anatomy examines similarities in limb structures among different species, showing shared ancestry.
- Molecular biology uses genetic and protein data to reconstruct evolutionary relationships.
Key Terms & Definitions
- Evolution — Change in species over time.
- Natural selection — The process by which individuals better adapted to their environment survive and reproduce more.
- Fossil — Remains or imprints of a living organism found in geological formations.
- Comparative anatomy — Study of similarities and differences in body structures among species.
- Molecular biology — Study of biological processes at the molecular (gene and protein) level.
- Geometric progression — Exponential population growth pattern.
Action Items / Next Steps
- Read about radiometric dating and genetics in upcoming chapters.
- Review chapter one to reinforce key concepts before moving to chapter two.