1. Darwin & Natural Selection
Chapter 22

2. I. History of Science Carolus Linnaeus (1707 – 1778)
Developed taxonomy – naming and classifying of organisms
Developed binomial nomenclature – two part naming system consisting of genus and species

3. B. Charles Lyell (1797 – 1875) 1. Geologist, friend of Darwin’s 2
B. Charles Lyell (1797 – 1875) 1. Geologist, friend of Darwin’s 2. Geologic processes are slow are have occurred over long expanses of time (***Earth is a lot older than was thought***)

4. C. Jean-Baptiste de Lamarck (1744 – 1829)
1. Developed a theory of evolution based on two principles
a. Use and disuse – parts of the body used more become larger and stronger and vice-versa b. Acquired characteristics can be inherited * His idea that organisms evolve was correct, but his explanation of how was not!

5. D. Charles Darwin ( ) 1. Traveled on the HMS Beagle from 1831 – 1836, observing and collecting species 2. Developed the theory of evolution by natural selection

6. II. Natural Selection A. Major Principles
Individuals in a population vary in their traits, many of which are heritable
a. Adaptations – heritable characteristics that enhance an organism’s ability to survive and reproduce in specific environments
What is your favorite animal? What is a characteristic that animal has that adapts it to its habitat or lifestyle?

7. 2. More offspring are produced than can survive
2. More offspring are produced than can survive. There are more individuals than the environment can support  COMPETITION!!!

8. 3. Individuals with adaptations that are better suited to their environment are more likely to survive and reproduce than those that do not have those traits.

9. ***POPULATIONS EVOLVE, INDIVIDUALS DO NOT!!!
Evolution occurs as the unequal reproductive success in a population causes an increase in numbers of individuals possessing the desirable traits and a decrease in numbers of those not possessing desirable traits
***POPULATIONS EVOLVE, INDIVIDUALS DO NOT!!!

10. a. Fitness is measured by reproductive success, not lifespan

11. Tip: When explaining evolution, avoid any language that makes it sound like a species/organism “needs” or “wants” a feature so it evolves. Don’t write “survival of the fittest.” Discuss how selection favors a feature which results in leaving more offspring. Evolution is not goal oriented.

12. ***Natural selection works on phenotypic variations in a population!!!
B. Selection Pressures - biotic and abiotic (living and non-living) factors in the environment that make some variations more favorable than others
Ex. Selection pressure for lynx is capturing food – favors any variation that makes the lynx a better predator. Selection pressure for rabbit is avoiding predation. Any variation that helps the rabbit avoid predation helps it survive longer to reproduce more.
***Natural selection works on phenotypic variations in a population!!!

13. 1. Environments change constantly, so selections pressures change, too
Ex. Climate change has impacted when flowering plants first bloom. The majority of plants now bloom earlier than at any time in the last 250 years. This, in turn, will impact insects and birds that depend on the timing of these flowers blooming.

14. 2. Convergent Evolution - 2 species that are not very closely related resemble each other because they have adapted to similar environments (have responded to similar selection pressures)
Given similar circumstances, evolution will occur in the same way in unrelated species

15. a. Analogous structures – structures that have the same function/address the same environmental challenge but do NOT indicate close relatedness

16. III. Artificial selection – process by which species are modified by humans selecting for traits A. Darwin bred pigeons to help him further test/develop the ideas he started to formulate on the Beagle