1. AND ADAPTATIONS NATURAL SELECTION 1

2. CHARLES DARWIN His theory of evolution by natural selection explained: Where all of the astonishingly diverse kinds of living things came from How they became exquisitely adapted to their particular environments. 2

3. WHAT IS NATURAL SELECTION? Natural Selection is the process where organisms that have traits that better enable them to adapt to specific environmental pressures (ex. predators, climate change, competition for food and mates, etc.) will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring those favorable traits will get passed on. HUH?????? Advantageous traits get passed on More likely to survive and reproduce 3

4. YOU NEED BABIES TO PASS ON GENES 4

5. NATURAL SELECTION 1. There is genetic variation (different traits). 5 Example: Two green beetle parents reproduce and they have green and brown beetle offspring

6. NATURAL SELECTION 2. There is an overproduction of offspring to ensure survival. 6 Example: green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do. The environment cannot support unlimited population growth because there are not enough resources Not all offspring will live and get to reproduce because of various environmental pressures, so parents often overproduce to ensure at least some survive

7. NATURAL SELECTION 3. There is a struggle for existence. 7 Example: The surviving brown beetles have brown baby beetles because this trait has a genetic basis and gets passed on There are natural pressures that exist in an organism’s environment that make it difficult to survive: predators, climate change, competition for food, mates and territory, etc. The organisms that have the characteristics that allow them to overcome these pressures survive and can then live and reproduce

8. NATURAL SELECTION 4. End result: new species 8 The organism with the advantageous traits lives and reproduces, passing along those genes Over several generations, a new species arises, made up of all the advantageous traits passed on from their ancestors Example: the favorable brown color trait gets passed down several generations until all of the beetles are brown, creating a new brown-beetle species

9. GALAPAGOS ISLAND FINCHES In the case of the finches on the Galapagos Islands, the 13 different species are believed to all be descendants from a common ancestor in South America The original species of finch ended up on the Galapagos Islands and the finches adapted to a particular niche in order to survive As the finches adapted to the different niches on the islands, they evolved into a unique types of finches over time 9

10. 10 Crushing Food (e.g. Seeds) Getting Food from inside a tree

11. HOW ORGANISMS ADAPT Adaptations are characteristics that enable organisms to better survive and reproduce There are three types of adaptations: Structural – physical feature Physiological – physical or chemical event Behavioral – what an organism does 11

12. STRUCTURAL ADAPTATIONS A physical feature of an organism that allows it to survive Example: Polar bears have white fur to help camouflage them in the white snow 12

13. PHYSIOLOGICAL ADAPTATIONS A physical or chemical event that occurs in the organism’s body that help it survive Example: snakes produce poisonous venom to protect itself against predators 13

14. BEHAVIORAL ADAPTATIONS Refers to what an organism does to survive in the unique conditions of its environment Example: Possums play “dead” to avoid predators 14

15. THE END. SORT OF So, now that we know what organisms do to survive, what happens to those that don’t or eventually grow old and pass on? 15