Transcript Evolution Free Response

•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?
Change in DNA
Sex cells
Mutations
Causes
Harmful
99.999…%
Body cells
Pass to offspring
Random mistakes during replication
Beneficial
0.000…%
Mutagens
•Radiation (Ultraviolet radiation, X-Rays
•Chemicals
Organism better
adapted to
environment
More chances of surviving
+
New beneficial changes
New species
Crossing over
Sexual
reproduction
New
combination
of genes
Independent
assortment of
chromosome
s
Fertilization
Exchange of DNA segments
Meiosis
between non-sister chromatids (prophase I)
Random
recombination of
genes
Combination of genes
from two different individuals
Meiosis
(anaphase I)
gametes
gametes
Egg (female)
+
Sperm (male)
Zygote
• 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.