Darwin’s Points Page 71 We will be writing down 6 points of the theory of natural selection and 3 different types of adaptations.

The Theory of Evolution It’s a Theory….what does that mean? What is evolution? Change in something over time. Have humans changed over time? Yes Wisdom teeth Goose bumps Appendix, tonsils, gall bladder

The Theory of Evolution It’s a Theory….what does that mean? What is evolution? Change in something over time. Have humans changed over time? Yes Wisdom teeth Goose bumps Appendix, tonsils, gall bladder

NATURAL SELECTION From Darwin’s collection of evidence he created his theory of evolution sometimes referred to as the survival of the fittest

This theory is based on six points: 1. Overproduction More offspring are produced than can survive. Examples: Fish that lay millions of eggs, Sea turtles Rabbits, mice, spiders

Example of overproduction: Sea Turtles - lay from 70 to 190 eggs (depending on the species). Only about 1 out of 100 survive.

2. Competition Because of overpopulation, organisms of the same species, as well as those of different species, must compete for limited resources such as food, water, and a place to live. Interspecific competition – between different species Intraspecific competition – between the same species

These variations are passed onto the next generation. Differences occur among members of the same species. No two individuals are exactly alike. These variations are passed onto the next generation.

4. Survival of the Fittest Natural selection. Individuals in a species with traits that give them an advantage are better able to compete, survive and reproduce. Others die off without leaving offspring.

A species can reproduce successfully with its own kind. 5. Speciation Origin of new species. Over numerous generations, new species arise by the accumulation of inherited variations. When a type is produced that is significantly different from the original, it becomes a species. A species can reproduce successfully with its own kind.

Allows organisms to become better suited to their environment. 6. Adaptation The accumulation of characteristics that improve a species’ ability to survive over long periods of time. Allows organisms to become better suited to their environment.

Adaptations There are 3 broad categories of adaptations: Physiological Behavioural Structural

1. Physiological Physiological adaptations involve what is going on inside the body. Example: - hibernation of alligators - sperm whales blood - pesticide-resistant insects. - antibiotic resistant bacteria.

2. Behavioural An organism’s behavior may provide it with a better chance of surviving and reproducing. Example: - decorator crab - organisms using tools-sea otters - sea turtles finding their natal beaches

3. Structural Structural adaptations involve an organisms external anatomy. Examples: Webbed feet of ducks for swimming talons on eagles for grasping. Camouflage-cuttlefish, octopus

Why adapt? Why are things changing over time? Advantageous adaptations give an organism a competitive edge in the struggle for food, space, ability to reproduce and the ability to avoid predators. Habitats also change, so what was once an advantage may one day become a disadvantage. Successful (“the fittest”) organisms are the ones with adaptations that allow them to survive and to reproduce.