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 Darwins 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.