Dark-colored moths camouflaged (to hide) from predators in the polluted environment.

Some light-colored moths may have migrated in from other areas. Some light-colored moths may have other adaptations that are more important than color for survival. Some light-colored moths may taste bad. Some light-colored moths rested in areas other than the bark.

The tree trunks were covered with lichens, so light colored moths camouflaged better and survive.

The species could become extinct. The species does not evolve.

What is the Source of Variation? Mutations Change in DNA Random mistakes during replication Mutagens Radiation (Ultraviolet radiation, X-Rays Chemicals Body cells Sex cells Causes Pass to offspring Harmful …% Beneficial 0.000…% Organism better adapted to environment More chances of surviving New beneficial changes New species Random recombination of genes New combination of genes Sexual reproduction Crossing over Exchange of DNA segments between non-sister chromatids Meiosis (prophase I) Independent assortment of chromosome s Meiosis (anaphase I) + Fertilization Combination of genes from two different individuals Egg (female) Sperm (male) + Zygote gametes

Mutations change DNA, resulting in new traits. Sexual reproduction involves union of DNA from two parents, resulting in offspring different from either parent.

The environment changed and the wooly mammoth could no longer adapt. Increase of predators Increase competition with other plant-eaters. Overhunting by humans

Bears and canines share common ancestors. Miacis is an ancestor of bears and canines Bears are more closely related to raccoons than to the domestic dog.

The two animals area adapted to different environments.

GENETIC VARIATION Not all of the bacteria were identical. They had genetic variation. Some bacteria have genes to make thin cell walls and some have genes to make thick cell walls. SURVIVAL OF THE FITTEST Those bacteria with thick cell walls were better adapted to survive in the presence of the chemicals. This is known as survival of the fittest. DIFFERENTIAL REPRODUCTION These bacteria which survived, they reproduced and passed on the favorable genes – to have thick cell walls - to the next generation.