Ch.15 Darwin and Evolution

Who was Charles Darwin and what did he propose?

Darwin was a naturalist who concluded that present day species descended from ancient ancestors and changed gradually over time

What major idea did Darwin develop to explain evolution

The mechanism of evolution he proposed was natural selection, where individuals with favorable traits are more likely to survive and reproduce.

What observations led Darwin to believe Earth was very old?

He observed raised beaches, fossilized shells, extinct mammals, and marine fossils high in the Andes Mountains, suggesting long term geological change

What is biogeography?

The study of the geographic distribution of life on Earth and how it relates to past geological events.

Why were the Galápagos Islands important to Darwin’s ideas?

Species on the islands were slightly different from mainland species and varied from island to island, suggesting adaptation to different environments.

What did Darwin observe about Galápagos finches?

Their beaks differed in shape and size depending on diet, showing natural selection in action.

What is differential reproductive success?

The idea that individuals with favorable traits produce more offspring than others.

What is fitness in evolutionary terms?

The reproductive success of an individual compared to others in the population.

What is convergent evolution?

When unrelated organisms develop similar traits because they live in similar environments.

What is artificial selection?

Human-controlled breeding of plants or animals to produce desired traits

How is artificial selection different from natural selection?

Artificial selection is goal-directed by humans, while natural selection is driven by environmental factors.

What are fossils?

Remains or imprints of organisms from the past that document changes in life over time.

What is the fossil record?

The sequence of fossils in rock layers that shows the history of evolution over millions of years.

What are homologous structures?

Body structures that are similar because they come from a common ancestor, even if they serve different functions.

What are vestigial structures?

Reduced or nonfunctional structures that were useful to ancestors. Ex tailbone and appendix

What are analogous structures?

Structures that serve similar functions but are not built the same way and do not come from a common ancestor.

What embryological evidence supports evolution?

All vertebrate embryos have similar features such as a postanal tail and pharyngeal pouches, suggesting common ancestry.

What biochemical evidence supports evolution?

All organisms use the same DNA code, the same 20 amino acids, and similar molecules, indicating relatedness.

How do DNA comparisons support common descent?

Species with very similar DNA sequences are likely to share a more recent common ancestor.