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15.3 Evolution in Action
Standards
 CLE 3210.5.5 Explain how evolution contributes to the
amount of biodiversity
 CLE 3210.5.3 Explain how genetic variation in a
population and changing environmental conditions are
associated with adaptation and the emergence of new
species.
How does evolution work?
 Natural Selection can work in several ways:
 Convergent Evolution: the process by which unrelated
species become more similar as they adapt to the same
kind of environment
 Divergent Evolution: the process by which two or more
related but reproductively isolated populations become
more and more dissimilar
 Co-Evolution: the process by which two or more unrelated
species evolve together because of a symbiotic
relationship.
Convergent Evolution
 How it happens:
Two genetically different species adapt to the same
environment in similar ways resulting in similar
phenotypes.
 Example:
Convergent
Evolution
 Leads to
analogous
structures:
Divergent Evolution
 How it happens:
One species branches off into two or more different species
due to changes in environment or behavior.
 Adaptive Radiation:
an evolutionary pattern in
which many species evolve
from a single ancestral species
Divergent Evolution
 Leads to
homologous
structures:
Co-Evolution
 How it happens:
When two different species are dependent on each other; if
one changes the other must adapt or go extinct.
Artificial Selection
 Natural Selection = environment determines desirable traits
 Artificial selection = humans determine desirable traits
Exit Ticket
 m.socrative.com
 Room: stewart348
 Compare and contrast natural selection with
artificial selection