EVOLUTION Cumulative effects of change on a POPULATION through vast periods of time Involves a change in a POPULATION, not in individual members Recombination of genes during crossing over makes you DIFFERENT Genetic VARIATION provides the material on which evolution acts

Variation a deviation from the normal recognized characteristic for that species Small differences among individuals that provides the raw material for evolution

Variation Variation improves chances a SPECIES will survive under CHANGING environmental conditions Some individuals will have a better chance of surviving to adulthood and producing offspring Variations are created from mutations and are rare and random events If the mutation is “good” or helpful, it may be passed on to future generations

Example of how Variation helps in Evolution Most deer are brown A mutation causes some deer to be born “albino” Usually this is bad because predators can see them more easily If we enter a new ice age, albino deer with have an advantage because they will blend in with the snow This ensures survival of deer as a species

NATURAL SELECTION

Natural Selection is…. A mechanism of evolution whereby members of a population with the most successful adaptations to their environment are most likely to survive and reproduce “Survival of the Fittest”

Selection…. Favoring organisms best fit to a given environment

Without VARIATION in a population there could be NO NATURAL SELECTION

There are two types of Selection

Natural Selection Artificial Selection Selection BY NATURE to favor those with “good” adaptations, to survive AND REPRODUCE Selection BY HUMANS to breed in “good” characteristics, breed out “bad” characteristics

Natural selection is based on adaptations any trait which enables an organism to respond (adapt) to its environment and allows it to survive and reproduce Adaptations :

Camouflage : species blends in with its surroundings

organisms looks very similar to another organism Mimicry:

Two of these are Bumblebees(with stingers) and two are Robber Flies (which also make a sound similar to a bee). If you were a predator, could you "bee" sure of the difference?

Which is poisonous

Charles Darwin’s theory of natural selection Overproduction of offspring: more offspring are produced than can survive Struggle for survival: organisms compete with each other for limited resources

Evolution Means “change over time” FACT: We have seen species change over time

Other evolution theories…..

SPECIATION: The emergence of a new species from pre-existing species

What makes a species? Organisms that can breed and create fertile offspring in nature

Horse + Donkey = Mule Mules are sterile and cannot reproduce! Horses and donkeys are different enough to be separate species.