Evolution
descent with modification
James Hutton
Gradualism- Showed change was a slow, continuous process
Charles Lyell
Uniformitarianism- fossils were always there
Lamarck
adaptions=helped survive environment
extinct species replaced by descendants
Lamarckism
a giraffe’s father stretched its neck, so the baby has a longer neck
Darwin’s theory
descent with modification
natural selection
frequency of allele
p+q=1
frequency of individuals
p^2+2pq+q^2=1
p^2=AA
2pq=Aa
q^2=aa
Homologous
forms were related by a common ancestor but used differently (human and dog limb)
Vestigal structures
remnants of homologous structures with no function (blind salamanders with eyes)
analogous structures
unrelated species with similar uses (torpedo shape for swimming)
Prezygotic barries- no mating attempt
(b4 fertilization)
-habitat isolation
-temporal isolation
-behavioral isolation
prezygotic barrier- mating attempt
-mechanical isolation
-gametic isolation
post zygotic barrier
-reduced hybrid viability (hybrid embryo fails to develop or weak)
-reduced hybrid fertility (hybrid survives but is sterile)
-hybrid breakdown (2nd gen. hybrids are feeble or sterile)
allopatric speciation
(involves geographic isolation)
sympatric speciation
(occurs in the same geographical area)
H-W conditions
no mutations
mating is random
no selection
large population size
no gene flow in or out
Mechanisms of microevolution
Natural selection
Founder effect
Bottleneck effect
Gene flow
Different forms of selection
stabilizing selection
directional selection
diversifying selection (disruptive)
frequency dependent selection
sexual selection
Stabilizing selection
Robins who lay more than 4 eggs result in malnourished chicks
Directional selection
One extreme phenotype is favored over the other
Diversifying (disruptive) selection
two or more extremes phenotypes are selected, while the other average is against.
frequency dependent selection
the lizard colors
sexual selection
sexual dimorphism- the red cardinal distract
