Darwin proposed natural selection as the mechanism of evolution Ch. 14.3

Darwin’s Theory of Natural Selection A POPULATION  group of individuals of the same species living in the same area at the same time

If one species of animal lives on an island, that POPULATION is different from a separate species living on the same island

Observations Lead to a Question 13 species of finches unique to the Galapagos Islands. –Closely resemble a species near S. American’s mainland What is the hypothesis behind this?

More Observations Lead to an Idea Based his theory on 2 key sets of observations –Only small % of offspring will survive each generation –Population VARIATION  differences among members of the SAME species

Using these observations led to NATURAL SELECTION

Artificial Selection ARTIFICIAL SELECTION  selective breeding of domesticated plants and animals to produce offspring with genetic traits that human value –When do you think this is used? What type of industry?

Pesticides – Natural Selection in Action Some insects have evolved in order to become resistant to certain pesticides –Initial results would kill the bugs, what would happen as the generations continue?

Concept Check In Darwin's view, what conditions lead to a struggle for existence among individuals in a population? What is the goal of artificial selection? Why does a specific pesticide become less effective over time?