Dark-colored moths camouflaged (to hide) from predators in the polluted environment.
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Transcript of Dark-colored moths camouflaged (to hide) from predators in the polluted environment.
•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
Harmful99.999…%
Beneficial0.000…%
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 overExchange of DNA segments between non-sister chromatids
Meiosis (prophase I)
Independent assortment of chromosomes
Meiosis (anaphase I)
+
Fertilization Combination of genesfrom two different individuals
Egg (female)
Sperm (male)
+ Zygote
gametes
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 VARIATIONNot 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 FITTESTThose 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.
