evolution—change over time, the process by which modern species have descended from ancient...
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Evolution—change over time, the process by which modern species have descended from
ancient organisms
Darwin’s Theory of Evolution
Who was Charles Darwin?
http://www.pbs.org/wgbh/evolution/library/11/2/e_s_2.html
Artificial Selection—selection by humans from natural variation among different organisms for
breeding of useful traits
Fig. 22-9
Kale
Kohlrabi
Brussels sprouts
Leaves
Stem
Wild mustard
Flowersand stems
Broccoli
Cauliflower
Flowerclusters
Cabbage
Terminalbud
Lateralbuds
Selective Breeding—method of improving a species by allowing only those individual organisms with desired characteristics to
produce offspring
Hybridization—breeding technique that involves crossing
dissimilar individuals to bring together the best traits of both
organisms
Genetic engineering—the process of making changes in
the DNA code of living organisms
Ex.-inducing mutations to increase genetic variation
Natural variation—genetic differences among individuals
of a species
Genetic variability starts with natural mutations
Struggle for Existence—members of each species
compete regularly to obtain food, living space, and other
necessities of life
Adaptation—any inherited characteristic that increases
an organism’s chance of survival
Camouflage as an example of evolutionary adaptaition
Question: What would happen if a well-adapted population experienced
a sudden major change in its environment
Answer: If the population had a variety of traits some of
them may survive and reproduce in the new
environment, if not they would probably become extinct
Descent with modification—principle that each living species has descended, with changes, from other species over time
Homologous structures—structures that have different
functions but develop from the same embryonic tissue
Early development
The early embryos of many animals with backbones are so similar that they can be hard to
tell apart
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