1 / 13

The Theory of Natural Selection

The Theory of Natural Selection. Artificial Selection. Humans created diversity choosing specific traits to breed Dogs, Crops, Livestock Humans selected (not naturally) traits thought to be advantageous Only inheritable traits can be passed down

brian-guy
Download Presentation

The Theory of Natural Selection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Theory ofNatural Selection

  2. Artificial Selection • Humans created diversity choosing specific traits to breed • Dogs, Crops, Livestock • Humans selected (not naturally) traits thought to be advantageous • Only inheritable traits can be passed down • Importance: Shows life can change over a period of time

  3. Dog traits have been selected by breeders for centuries to produce various breeds.

  4. Plants have been bred to produce certain traits for human use also!

  5. Natural Selection With adaptation Without adaptation Not all these wildebeest will survive These kittens have variations • Four factors: 1) Overpopulation: more offspring are born than can survive 2) Variation: individuals of a population have differences 3) Adaptation: Some variations allow a better chance of survival 4) Descent w/ modification: Those with advantages will reproduce  more of the population will have the advantage

  6. The Myth

  7. Which rabbit is best adapted to this environment? Over time, those not adapted most likely die…that’s natural selection!

  8. Which rabbit is best adapted? Do the dark rabbits turn white? No! They get eaten. (survival of the fittest)

  9. Struggle for Survival • Populations do not grow unchecked • Limiting Factors: food, water, shelter, disease, predators • Fitness: measure of the ability to survive & produce more offspring

  10. New environments are continally created. Life adapts with the changing conditions.

  11. Changing Environments • Evidence of a changing Earth • Marine fossils atop mountains • Dry valleys with ocean fossils • Rivers create canyons • As the environment changed due to continents drifting… • Those with adaptation: more likely to survive & reproduce • Those without adaptation: more likely to perish

  12. Natural Selection in Action: The Peppered Moth Analysis Before the industrial revolution, the trees in the forest around Manchester, England were a light grey/green due to the color of lichens (fungus) on their trunks. Peppered moths, or Bistonbetularia, which lived in the area, were mostly lightly colored with dark spots. However, there was some color variation between the moths. The most common moth color was light with dark spots and the least common were dark with light spots. Because there were not enough resources to support the entire population, the members of this species had to compete for survival. Their coloring, when against a similar background, served as camouflage against predators such as birds and lizards, thus increasing chances of survival.

  13. Natural Selection in Action: The Peppered Moth Analysis As the Industrial Revolution progressed, the trees became covered with sulfur dioxide, turning the trunks dark.

More Related