Transcript The Development of Evolutionary Biology

Descent with Modification: A
Darwinian View of Life
THE EVOLUTION TIME LINE
Dance
I. THE PLAYER
A.
1.
2.
3.
Charles Darwin (1809-1882 )
Occupation: Naturalist
Most Famous For: Origin of Species (1st book)
Contribution to Evolutionary Biology:
Essay - “Theory of Natural Selection” - the mechanism of change in
evolution
B. Alfred Russel Wallace (1823-1913)
-Essay title: “On the Tendency of Varieties to Depart
Indefinitely from the Original Type”
Darwin Pictures
Darwin focused on
adaptations – inherited
characteristics of organisms
that enhance their survival
and reproduction to a
specific environment
II. Darwin’s (Wallace) Theory of Natural Selection
Observations From Nature
Inferences
1. Members of a
population often vary in
their inherited traits
1. Individuals whose inherited
traits give them a higher
probability of surviving and
reproducing in a given
environment tend to leave
more offspring.
2. All species can produce more
offspring than their
environment can support, and
many of these offspring fail to
survive and reproduce.
2. Unequal ability to survive
and reproduce leads to
accumulation of favorable
traits in a population over
generations
Note: Darwin did not introduce the concept of mutations producing new varieties.
Darwin believed the variety was always in the genes. Mutation is a post-Darwinian
concept.
III. Evidence for Evolution
A. Natural Selection in Response to Introduced Species
1. Soapberry bugs use mouth-like part to feed on seeds inside fruits
a. Southern FL – feeds on native balloon vine vs. central FL
goldenrain tree (new tree from Asia)
b. feed best when mouthpart matches depth of seeds in fruit
c. Natural selection selected for shorter beaks in central FL
2. The Evolution of Drug-Resistant Bacteria - MRSA
a. MRSA – methicillin-resistant Staphylococcus aureus
b. Penicillin in 1943  bacterial resistance  production
of antibiotic methicillin 1959  bacterial resistance…
3. Take-away from examples
a. Natural selection is a process of editing what already exists
b. Natural selection acts on what characteristics are favorable at
the time in a particular environment
B. Fossils: Preserved remains of ancient organisms
1. Implication: organism were different than now
2. Older fossils are found in older and deeper strata (layers)
C. Homology– Similarities resulting from common ancestry
1. Anatomical similarities
a. Must separate homology (related structures) from
analogy (similar functions)
b. Analogy leads to convergent evolution (organisms
similar due to similar yet VERY DISTANT
environments; they aren’t related)
c. May explain vestigial organs - organs of no apparent
function; (appendix)
2. Molecular similarities
a. All life shares same genetic code and amino acids in
proteins
b. Organisms have homologous genes (genes in common)
ex. 18S ribosomal RNA gene
D. Biogeography: The geographic distribution of species
1. Species diversity is due to natural selection found in different areas
2. Diversity may reflect divergent evolution
3. Diversity may reflect convergent evolution
Divergence (Fruit fly)
Convergence (Flying squirrel)
Mammalian forelimbs:
homologous structures
Slide 17
Analogous structures
Slide 101
Human Vestigial Structures
Slide 16
What if all the spores
of this puffball
actually germinated?
Slide 11
Asian Ladybird Beetles
Slide 11
What do these plants have in common?
We artificially selected traits of
the wild mustard
Slide 11
Slide 15
Clone USA300 – causes
lethal infections to skin,
lungs, and bloods
MRSA infection proliferation
Slide 15
COMPARISON of 18S rRNA gene sequences
Slide 7
The Origins of Evolutionary Thought
Slide 3
Elephant Evolution “Tree”
Slide 7
Slide 7