CORNELL NOTES: CHARLES DARWIN & NATURAL SELECTION EQ: How do the traits in populations change over time through natural selection? CORNELL NOTES: CHARLES DARWIN & NATURAL SELECTION

Who is Charles Darwin? Published in 1859 1831-1836 Darwin Darwin 1831-1836 HMS Beagle Galapagos Islands Published in 1859 The animals on the Galapagos were unlike any others on the planet, could they have changed naturally from South American ancestors? 1809-1882

The Crazy and Unique Animals of the Galapagos

Darwin’s Big Theory: Natural Selection Natural Selection (Survival of the Fittest): The idea that organisms that are the best adapted for their environment will survive and reproduce, thus passing on the advantageous traits to the next generation. Fitness – A measure of how well an organism is able to survive and reproduce in a given environment.

Factors Required for Natural Selection 1. Genetic variations in the population 2. competition (more organisms are produced than survive) 3. Some genetic variations are favorable 4. Favorable variations will allow for survival 5. A population will change over time.

Which organism is more fit now? Originally, the vast majority of peppered moths were light-colored, which effectively camouflaged them against the light-colored trees and lichens in which they rested upon. However, because of widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees that peppered moths rested on became blackened by soot. What effect do you think this had on the population of light colored peppered moths? Why? What about the dark colored peppered moths? What is the variation in this population? Which variation is more favorable? Which variation will allow for survival? Which organism is more fit now? How will the population of peppered moths change over time? Peppered Moth Simulation

What is the variation in this population? Which variation is more favorable? Which variation will allow for survival? How will the population of bugs change over time? Which organism is the most fit?

Natural Selection at Work And now we introduce… COMPETITION! For what? I need some volunteers… Shortstack Island: Food grows close to the ground Giant Isle: Food grows high in the trees

Natural Selection at Work The monarch butterfly looks very much like the viceroy butterfly in its wing pattern and colors, but they are quite different otherwise. The monarch is distasteful to predatory birds, while the viceroy is not distasteful. It is believed the similarity in coloration is an adaptation. Briefly identify which butterfly has adapted, and describe the adaptation.

Natural Selection at Work The farmers in an area have been using an insecticide for several years to kill insects that destroy tomato crops. Despite using the insecticide in increasing amounts, they are finding that the fruit is being destroyed again and that the same insects are responsible. Using your knowledge of natural selection, describe how this situation is possible.

Natural Selection Follow-Up Worksheet Homework Natural Selection Follow-Up Worksheet