Change Over Time

Evolution A cumulative change in the characteristics of organisms or populations from generation to generation Slow process Many small changes collect to form a new species Species - group of the same organism, organisms that can breed together

Charles Darwin Natural Selection Observed the main mechanism of evolution on his travels around the world. Natural Selection

Galapagos Islands Island chain off the coast of Peru Islands vary in terrain and vegetation Darwin studied finches on several of the islands

Galapagos Finches Many different species are found on the island Each finch is well adapted to their island habitat How? Why?

Darwin’s Theory of Evolution by Natural Selection (OCVSRS) (Potential for) Overpopulation - Unchecked reproduction causes exponential population growth.

Darwin’s Theory of Evolution by Natural Selection (OCVSRS) Competition - for resources occurs because resources are limited (space, clean water, food, etc…) Ex. Predator Prey relationship

Darwin’s Theory of Evolution by Natural Selection (OCVSRS) Variation with in a population. Some organisms may be… faster or slower, stronger or weaker, more resistant to a disease Blend in with surroundings better Etc.

Darwin’s Theory of Evolution by Natural Selection (OCVSRS) Selection - some variations increase the chance of survival because they Out run a predator Hide from a predator Find clean water Use different food sources Etc..

Darwin’s Theory of Evolution by Natural Selection (OCVSRS) Reproduction - organisms that are selected for survival can pass on their traits Over time the frequency of favorable traits will increase in the population

Darwin’s Theory of Evolution by Natural Selection (OCVSRS) Speciation - Process of forming a new species Over time many changes accumulate If populations are different enough that they can no longer mate with each other. The two populations are considered different species.