Download Zea mexicana

Evolution by Selection
Natural: Environment selects for fittest traits
Artificial: Humans select for desired traits
Teosinte
Zea mexicana
Artificial selection
Corn
Zea mays
Genetic Drift: changes in gene
frequency happen by chance
Freq.
14/20 = 0.7
6/20 = 0.3
v
River
Genetic Drift: changes in gene frequency happen by chance
Freq.
1/10 = 0.1
River
9/10 = 0.9
v
Freq.
5/10 = 0.5
5/10 = 0.5
Homology: similarity of the structure, physiology, or
development of different species of organisms based
upon their descent from a common evolutionary
ancestor
Analogy: a functional
similarity of structure based
not upon common
evolutionary origins but
upon mere similarity of use
Homology
Common
ancestor had
same feature
Humerus, radius, ulna,
carpals, metacarpals,
phalanges
Analogy
No known
Common
ancestor