Natural Selection 1 CHAPTER 14 3 Darwins Theory

Natural Selection 1 CHAPTER 14. 3

Darwin’s Theory 2

3 Starts with a POPULATION, which is a group of individuals of the same species in the same area at the same time Darwin collected finches from different islands in the Galapagos

Observations 4 There were 13 finches found, and all resembled a finch found on the South American mainland Each finch had a unique beak that was good for where the bird lived

New Idea 5 Darwin saw that organisms produce way too many offspring There are limited resources in nature for this leads to competition Only a small number of offspring will survive

6 Darwin’s second observation was that there is variation in organisms VARIATION is just the differences within a population A lot of variation is passed onto offspring

7 This lead to theory of Natural Selection It happens over many, many generations and can create two separate species from one ancestor

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Artificial Selection 9

10 ARTIFICIAL SELECTION is when humans choose the traits to be passed onto next generations Dogs are a great example

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Pesticides 12

13 Pesticides are poisons used to kill insects that eat plants Some insects have natural resistance to the pesticide and have more offspring Whole population then becomes resistant!

14 1. “A pesticide does not create resistant individuals, but selects for resistant insects that are already present in the population. ” 2. “Pesticide resistance offered no advantage until pesticide application changed the local environment. ”

Hmm… 15 Pesticides…natural resistance…does this remind you of anything we did recently?