This document summarizes key aspects of the theory of evolution through natural selection as described by Charles Darwin. It discusses how Darwin observed similarities between plants and animals in the Galapagos Islands and South America, leading him to propose that their ancestors had migrated and evolved over time through natural selection. The document then defines natural selection and adaptation, and describes evidence that supports evolution, including fossils, homologous and vestigial structures, and similarities in DNA and proteins between related species. It provides examples of Darwin's finches and the formation of new species through divergence and speciation.

1. CHAPTER 13 NOTES “ THE THEORY OF EVOLUTION”

2. I. THEORY OF EVOLUTION

3. A. Evolution - change over a period of time

4. B. Charles Darwin – English naturalist 1. Studied the plants and animals of the Galapagos Islands. 2. Noticed that the plants and animals of the Galapagos Islands were similar to those off the coast of South America .

5. 3. Suggested that the explanation for this similarity was that their ancestors had migrated from South America to the Galapagos Islands.

6. 4. Published ideas about evolution in his book “Origin of Species” – concluded that evolution occurs because of natural selection . Four basic concepts: Variations exist among individuals in a population Variations can be inherited More offspring are produced than can survive. Variations that increase an organism’s chance of surviving and reproducing are more likely t be passed on to the next generation.

7. II. EVOLUTION BY NATURAL SELECTION

8. A. Natural selection – individuals that have traits that better suit their environment are more likely to survive and reproduce successfully. “ survival of the fittest ” B. Adaptation – physical and behavioral traits that allow organisms to become better suited to their environment. 1. Ex: coloring of an animal to blend in to environment Ex: thick leaves of a cactus to store water Penguin adaptations – short wings, dense bones http://www.gma.org/surfing/antarctica/penguin.html

9. C. Gradualism – model of evolution in which change occurs at a slow , constant rate. D. Punctuated Equilibrium – model of evolution in which periods of rapid change in a species are separated by periods of little or no change (possibly caused by suden or drastic changes in environment).

10. III. EVIDENCE OF EVOLUTION

11. A. Fossils – provide an actual record of Earth’s past life forms . 1. shells, bones 2. any traces of dead organisms ( leaf imprint in rock ) 3. footprints , insects trapped in tree sap , insects trapped in tar

12. B. Anatomy and Development 1. Vestigial structures – structures that have been reduced in size because they no longer serve an important function. Ex: hind leg bones of whales, human appendix . 2. Homologous structures – anatomical structures from a common ancestor. Ex: forelimbs of vertebrates

13. B. Anatomy and Development (continued) 3. Embryo development – at some time in their development, all vertebrate embryos have a fin , tail , and pharyngeal pouches .

14. 4. Biological molecules – as species evolve, one change after another becomes part of their genetic instructions. a. Closely related species will show similarities in nucleotide sequences (DNA). b. Closely related species will have similar amino acid sequences (proteins) c. If species have changed over time, their genes should have changed. B. Anatomy and Development (continued)

15. IV. EXAMPLES OF EVOLUTION

16. A. Darwin’s Finches 1. Studied 9 distinct species 2. All similar except for beak shape 3. Evolved from common ancestors 4. Beak shape was affected by the availability of food.

17. B. Formation of New Species 1. divergence – the accumulation of difference between species or populations. Divergence leads to: 2. speciation – process by which new species form 3. subspecies – populations of the same species that differ genetically because they have adapted to different living conditions.