Download Evolution History

Evolution: A Revolutionary Idea
A. What is Evolution?
1. Several definitions
video 1
video 2
a. descent with modification (Darwin)
b. change in gene
frequencies within a
population
c. All the changes that have
transformed life on earth
from its earliest beginnings
to the immense diversity
existing today
Evolution: A Revolutionary Idea
We can allow satellites, planets,
suns, universe, nay whole systems
of universe, to be governed by
laws, but the smallest insect, we
wish to be created at once by
special act.
The Evidence of Change?
 Fossil Record
“We must, however, acknowledge, as it
seems to me, that man with all his
noble qualities... still bears in his bodily
frame the indelible stamp of his lowly
origin.”
The Evolution of Evolutionary
Thinking
Jean Baptiste Lamarck: Inheritance of Acquired
Characteristics
Main Points
Organisms adapted to environment
a. Use and disuse
i. organisms lost parts because they did not use them — like
the missing eyes & digestive system of the tapeworm
ii. Constant use leads to a larger organ: blacksmit muscles
b. Transmission or passing on of acquired characteristics
The Evolution of Evolutionary
Thinking
A. Historical Development
1. Jean Baptiste Lamarck
2. August Weismann
a. Disproved Lamarck ideas by
chopping of the tails of mice
b. What?
History
A. Historical Development
1. Charles Darwin
a. Study theology at Cambridge
b. 1831 appointed naturalist aboard the
ship HMS Beagle
i. mission was to create maps for the
British Navy
c. Darwin took surveys and collected
samples of plants, animals, rocks, and
fossils
History
A. Historical Development
1. Charles Darwin
d. Most famous observations: Galapagos
Islands where he spent 2 months
e. Eventually sailed around the world 18311835
video1
video 2
History
Evolution
A. Historical Development
1. Charles Darwin
f. Wrote a 200+ page thesis in
1844 outlining his theory but he
did not publish
WHY?
g. Alfred Wallace: came to similar conclusions
as Darwin in 1858 from observations
collected in another area of the world
h. Darwin agreed to a joint presentation with
Wallace to the same scientific body.
History
A. Historical Development
1. Charles Darwin
a. Publishes Origin of Species in 1859
b. How does the public respond to the
book?
c. The first printing of the book sold out
the first day
History
A. 5 ideas of Darwin’s Theory
1. Overpopulation
a. Organisms produce more young than will survive
b. example:
Fly eggs: 250 eggs
by one female in
one laying
Praying Mantis
young from one
cocoon
Baby sea
turtles
A. 5 ideas of Darwin’s Theory
1. Overpopulation
2. Variation
a. There exists in a population a large
amount of variation
A. 5 ideas of Darwin’s Theory
1. Overpopulation
2. Variation
3. Struggle for existence
a. What do organisms struggle for?
i. Lion attack
ii. gazelle attack
b. Carrying Capacity: how many individuals can the
environment support
i. example: deer in CVNP
4. Survival of the strongest fittest
a. Those that survive are the best adapted
A. 5 ideas of Darwin’s Theory
b. Individuals that survive reproduce and
pass on favorable traits
c. “Fittest”: those that reproduce most successful
i. Differential reproductive success
5. Natural Selection
a. Environmental pressures select for the best adapted
b. Animated example: DDT and flies
B. People who helped Darwin
1. Thomas Malthus
a. minister, economist
b. Wrote: Essay on
Populations
c. Predicted that
population would grow
faster than food supply
d. Lead to Darwin’s
idea of struggle for
existence
B. People who helped Darwin
1. Charles Lyell
a. geologist
b. Wrote: Principles of Geology
c. Proposed the idea of Uniformitarianism
i. Geological processes are constant
through time
ii. Challenged the prevailing thought that
the earth was young
iii. Darwin needed large periods of time
for natural selection to work
iv. Uniformitarinism provided Darwin the
time element needed for his theory
B. People who helped Darwin
1. Charles Lyell/ Uniformitarianism
Natural Selection: How Evolution Works
Overpopulation
Genetic Variation
Struggle for Existence
Differential Reproductive Success
Selection occurs based on:
• the interaction of the environment and
the existing population variations
• the more severe the environmental pressure,
the more severe the selection process
Natural Selection:
• the environment shapes or refines organisms
adaptations
Environmental Pressures
• resources: food, water, shelter
• climate: cold, hot, wet, dry
• predation: how does one survive?
Evidences
A. Anatomical
1. Fossils
a. Remains or traces left in rock
strata (layers) by previous
organisms (video: becoming a
fossil)
b. Preserved in: rocks, bogs, tar
amber, ice
c. Types of preserved samples:
imprints, castings, and amber
Evidences
A. Anatomical
1. Fossils
d. Transitional records
i. Classic example: the horse
e. Famous fossils
i. archeopteryx;
• bird or reptile?
Evidences
A. Anatomical
1. Fossils
e. Famous fossils
i. Coelocanth: living fossil
Evidences
A. Anatomical
1. Fossils
e. Famous fossils
Evidences
A. Anatomical
2. Comparative Anatomy
a. Homologous structures
i. Structures in different species
that are similar in structure but
serve different functions
Evidences
A. Anatomical
2. Comparative Anatomy
a. Homologous structures
i. Divergent evolution
 Divergent evolution
 when isolated populations of a
species evolve independently
 adaptive radiation: evolution of
many diversely adapted species
from a common ancestor
 Phylogenetic tree: graphic representation of
divergent evolution
 adaptive radiation: evolution of
many diversely adapted species
from a common ancestor
Evidences
A. Anatomical
2. Comparative Anatomy
b. Analogous structures
i. Structures shared by different
species that serve the same
function but look different
 example: wings of birds and
insects
 example: streamline body of
fish and aquatic mammals
 example: cactus/euphobia
Evidences
A. Anatomical
2. Comparative Anatomy
b. Analogous structures
ii. Convergent evolution
 different species being
“shaped” by similar environmental
pressures
Species a
Time
Species b
Evidences
A. Anatomical
1. Vestigial structures
a. Inherited organs or parts of
organs that are reduced in size or
non-functional Examples?
i. appendix
ii. coccyx
iii. wisdom teeth
iv. ear muscles
Evidences
A. Anatomical
1. Vestigial structures
iv. Whales and pythons: vestigial
hind limbs
v. Flightless birds: vestigial wings
vi. Blind, cave dwelling animalsvestigial eyes
Evidences
B. Embyrological evidence
1. def: related species exhibit similar
embryological development
•Found in all
a. segmented muscles
vertebrate embryos
b. gill pouches
c. tubular heart: no chambers
d. Aortic arches in gill region
Ernst Haeckel
•All of these
structures are
found in fish
Evidences
C. Molecular Evidence
question: what on the molecular level
would suggest relationships between
species?
1. DNA
a. the more similar the DNA:
i. common proteins
ii. common biochemical pathways
WHY?
Evidences
C. Molecular Evidence
1. DNA
How similar?
a. 96 – 99% similarity in
sequences
Evidences
C. Molecular Evidence
1. DNA
b. Found in every organism: from
bacteria to “man”
c. cytochrome C: found in every
aerobic organism / involved with
making energy
video
Evidences
C. Co-evolution
1. def: species that co-evolve
a. bacteria and humans
b. ants, fungus, and bacteria
D. Biogeography
1. def: study of the distribution of
life around the world
a. example: emus, ostriches, rhea
and extinct elephant bird all
found in the southern
hemisphere
WHY?
Evidences
C. Co-evolution Examples
Evidences
E. Microevolution
1. def: small changes in variations or gene frequencies
occurring in a population of organisms
2. Classic example: Industrial Melanism
a. def: The darkening of several species of moths during
the period of industrialization in many countries by the
spread of a gene controlling elevated melanin synthesis
Evidences
2. Classic example: Industrial Melanism
a. The selective pressure came from predators (insect
eating birds). The moth’s color provides camouflage.
b. Moths rest during the daytime on trees.
c. In rural areas where the air is clean the trees are
covered in lichen.
d. The peppered variety is better camouflaged when it
rests on these trees. The melanic form is easily seen.
e. In industrial areas air is polluted and the lichens die.
f. The tree trunks may also be covered in soot giving a
black background.
g. This favors the melanic form giving them a selective
advantage.
Evidences
3.Other examples
a. evolution of antibiotic resistant forms of bacteria
b. evolution of insecticide resistant insects (DDT and flies)
Evidences
F. Artificial Selection
1. Def: Selection of desirable traits by man to create
organisms with “improved” genetics or desirable traits
Evidences
F. Artificial Selection: plant selection
Two Modes of Evolution
1. Microevolution: Small changes within a population or gene
pool or shift in gene frequencies
2. Macroevolution: The formation of new species from other
species
The question is: What defines a species?