Evolution: How Change Occurs Chapter 14

14.1 Developing a Theory of Evolution evolutionary theory is fundamental to the study of Biology Genetics, ecology, and medicine are all based upon the evolutionary theory Fact or Theory? –Fact: fossils give evidence that organisms have changed over time –Theory: how the changes have occurred.

Lamarck – Acquired Characteristics Theory Noticed that organisms changed over time long before Darwin made his voyage on the HMS Beagle Relied on three assumptions that we now know are incorrect

1. Desire to Change All organisms were born with the desire to make themselves better adapted to their environment. Ex. Birds wanted to fly, so over many generations they acquired wings

2. Use and Disuse Using or not using a particular body structure leads to strengthening or disappearance of the structure (does this happen?)

3. Inheritance of Acquired Traits Believed that features acquired during an organism’s lifetime could be passed on to their offspring (What’s wrong with this idea?)

Lyell – Earth’s History Studied geology and determined that the Earth was very old and has changed over time Important because the Earth has to be very old in order to account for the millions of years needed for a species to evolve from a common ancestor.

Farming - Artificial Selection What farmers knew: -plants and animals vary greatly in their characteristics - Offspring share many characteristics of their parents -favourable variations could be enhanced through selective breeding

Malthus- population studies - Species produce more offspring than the environment can support - Only a small number will survive and reproduce.

14.2 – Evolution by Natural Selection Darwin’s Conclusion: Wild plants and animals have inherited variations Struggle for existence – only the “fit” survive Individuals whose characteristics are well-suited to the environment survive. Individuals whose characteristics are not well-suited to their environment either die or leave fewer offspring. (Survival of the Fittest)

Peppered moths – Natural selection in action Different colours are more successful in different environments…

Another example – antibiotic resistance in bacteria Some bacteria have natural resistance to antibiotics Using the antibiotic kills the ones that don't have this variation, the resistant ones survive and reproduce….

Make sure you can summarize: 1)Darwin’s process of Natural Selection (vs. Lamarck’s theory) 2) Survival of the fittest 3) the case of Peppered Moths