1. Section 15.1 Summary – pages 393-403
Breeding organisms with specific traits in order to produce offspring with ideal traits is called artificial selection.
(Intentional breeding for certain traits)
Who have we studied that bred organisms through artificial selection?
A Goldendoodle
(Golden retriever/ Poodle)
Mendel and the pea plants
Section 15.1 Summary – pages

2. Darwin and Natural Selection
Charles Darwin ( )
He was an English scientist and it took him years to develop his theory of natural selection.
He began in 1831 at age 22 when he took a job as a naturalist on the English ship HMS Beagle, which sailed around the world on a five-year scientific journey.

3. Section 15.1 Summary – pages 393-403

4. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
As the ship’s naturalist, Darwin studied and collected biological and fossil specimens at every port along the route.
The specimens were quite diverse, but he became curious about possible relationships among species because of similarities he saw.
Section 15.1 Summary – pages

5. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
One of the things Darwin observed is that in nature, the traits of individuals vary in populations.
Then these variations are then passed to offspring.
Darwin hypothesized that there was a force in nature that picked which traits are better for survival in a species.
Section 15.1 Summary – pages

6. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
On the Galápagos Islands, Darwin studied many species of animals and plants that are unique to the islands but similar to species on the mainland.
These observations led Darwin to consider the possibility that species can change over time, especially if exposed to different environments where they must adapt to different things.
Section 15.1 Summary – pages

7. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
He also observed that individuals struggle to compete in changing environmental conditions.
What do individuals compete for?
Only some individuals survive the competition and live to produce offspring.
Section 15.1 Summary – pages

8. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
Natural selection is the idea that organisms with favorable/beneficial traits survive, reproduce, and pass those traits to the next generation.
Organisms without these variations/traits are less likely to survive and reproduce.
Section 15.1 Summary – pages

9. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
Darwin proposed that natural selection explains how species change over time….
He had four ideas to explain how natural selection works.
1.In nature, organisms produce more offspring than can survive.
Section 15.1 Summary – pages

10. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
2. In any population, individuals have variations.
For example, color, size, and speed.
Section 15.1 Summary – pages

11. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
Individuals with certain useful variations are the ones that survive in their environment, passing those variations to the next generation.
Whereas individuals without those variations would not survive to reproduce.
Section 15.1 Summary – pages

12. Section 15.1 Summary – pages 393-403
Darwin and Natural Selection
Over time, offspring with the FAVORABLE variations make up most of the population.
The allele for the unfavorable variation may eventually cease to exist.
Section 15.1 Summary – pages

13. Why do you think more and more bad bacteria (like the kind that cause sinus infections) are becoming resistant to anti-biotics?
How do you think natural selection will affect this species of moth? (both the same species, just have variations)

14. Question 1
What is the difference between artificial and natural selection?
Section 1 Check

15. Natural Selection:
Nature’s way of making sure the best traits live on….
“Survival of the fittest”

16. Section 15.1 Summary – pages 393-403
ADAPTATIONS
Recall that an adaptation is any variation that aids an organism’s chances of survival in its environment.
Examples are:
Thorns on plants
Special colorings for an organism
Enhanced night vision
Section 15.1 Summary – pages

17. Section 15.1 Summary – pages 393-403
ADAPTATIONS
Some other structural adaptations are subtle.
Mimicry is a structural adaptation that enables one species to resemble another species.
In one form of mimicry, a harmless species has adaptations that result in a physical resemblance to a harmful species.
Section 15.1 Summary – pages

18. Section 15.1 Summary – pages 393-403
ADAPTATIONS
Another subtle adaptation is camouflage, an adaptation that enables species to blend with their surroundings.
Because well-camouflaged organisms are not easily found by predators, they survive to reproduce.
Section 15.1 Summary – pages