Transcript Evolution - Donald Edward Winslow

Evolution
General Zoology, 19 January 2011
Donald Winslow
Reading:
Hickman et al. 2011 Integrated Principles of Zoology,
th
15 ed., McGraw-Hill
Ch. 1 pp 13-15;
Ch. 6 pp 101-109, 111-121, 123-131
“Nothing in biology makes sense except in the light
of evolution.” --Theodosius Dobzhansky
Founders of evolution
Lamarck—inheritance of acquired traits
 Lyell—uniformitarianism & gradualism
 Malthus—exponential growth & limitation
 Darwin—natural selection, speciation
 Wallace—independently developed
theory of evolution by natural selection
& inspired Darwin to publish.

Darwin's theory of evolution
Change
Common descent
Speciation
Gradualism
Natural selection
Charles Darwin
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Voyage on H.M.S. Beagle, Galapagos
Natural selection & adaptation
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Population growth & limits to growth
Competition and heritable variation
Differential survival & reproduction
Gradual adaptation & speciation
Reproductive barriers & speciation
Evidence for evolution

Fossil record
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Marine organisms on mountaintops
Geological time & dating—isotope decay
Evolutionary trends—horses
Homology of vertebrate forelimbs (Fig 6.14)
“Ontogeny recapitulates phylogeny.”
- Ernst Haeckel
Flying Great Egret (Ardea alba). Photo by Karen Bays.
Bird wings are homologous to a human’s
arms.
Ontogeny & phylogeny

Pharyngeal gill slits
–
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Paedomorphosis
–
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Present in fish, reptiles, birds, mammals
Axolotls—salamanders that never grow up
Heterochrony
–
Change in the timing of development
Microevolution
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Population genetics
Gene pool
Allele frequencies
Hardy-Weinberg equilibrium
Allele frequencies
Example with allele (T) for ability to taste
phenylthiocarbamide (from Hickman, et al.)
Genotype
# of individuals
Copies of T
Copies of t
T/T
20
40
0
T/t
40
40
40
t/t
40
0
80
100
80
120
p = frequency of T = 80/200 = 0.4
q = frequency of t = 120/200 = 0.6
Forces that change
allele frequencies
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Mutation
Genetic drift
Nonrandom mating—e.g. assortative mating
Migration
Selection (natural, artificial, sexual)
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Relative fitness
Stabilizing, directional, & disrupting selection
Bright plumage of male Northern Cardinal—
A result of sexual selection.
Measuring genetic variation
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Protein polymorphism & heterozygosity
Gel electrophoresis
Quantitative characters
Dark-eyed Junco (Junco hyemalis) color variants
Leucistic “Purple” Finch
(Carpodacus purpureus)
Macroevolution
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Allopatric & sympatric speciation
Eastern
Hybridization, extinction
Meadowlark
Adaptive radiation (diversification) (Sturnella magna)
Gradualism, punctuated equilibrium
Mass extinction
Levels of selection

Genic, individual, kin, group, species