Transcript Evolution 2 - Groch Biology

Evolution Overview
Evidence for Evolution
A. Biogeography
1.
Geographical
distribution of
species
Evidence for Evolution
B. Fossil Record
1.
2.
Evolutionary transitions
New forms appearing/disappearing
Evidence for Evolution

Transitional Forms
Evidence for Evolution
C. Comparative Anatomy
1. Anatomical similarities between
species grouped in the same
taxonomic categories
Evidence for Evolution
2. Homologous structures
a. Similarity in characteristics from common
ancestor
Evidence for Evolution
Analogous structure
3.
a.
b.
Look similar because of environment
No common ancestor
Evidence for Evolution
Comparative Embryology
D.
1.
Closely related organisms go
through similar stages in embryonic
development
Evidence for Evolution

View comparative embryology
Evidence for Evolution
Molecular Biology
E.
1.
DNA, RNA, Protein Analysis, mitochondrial DNA
Evolution is Descent With Modification

Evolution only occurs when there is a
change in gene frequency within a
population over time.

Beetles and Drought
Beetles of a
different color
1st Year
2nd Year
Why are the beetles smaller the next
year? Evolution or environmental
influences?
Why are there less green beetles the
next year? Evolution or environmental
influences?
Basic Mechanisms of Evolutionary Change
I.
A.
B.
C.
D.
Mutation
Migration
Genetic Drift
Natural Selection
A.
B.
D.
C.
Genetic Variations
II.
Mutations (Genetic Variation)
A.
1.
2.
DNA copies incorrectly
External influences
Gene Flow (migration)
B.

any movement of genes from one population
to another
Sex (genetic shuffling)
C.

can introduce new gene combinations into a
population
Genetic Drift
III.
A.
B.
C.
Some individuals leave more descendants
Chance
Founder effect
Natural Selection
IV.
A.
B.
C.
Variation in traits
Differential reproduction
Heredity
D.

Fitness
how well an individual contributed its genes
to the next generation
Types of Natural Selection
E.
Stabilizing Selection
Types of Natural Selection continued
F.
Directional Selection
Types of Natural Selection continued
G.
Disruptive Selection
Coevolution
V.
•
two (or more) species reciprocally affect each
other’s evolution
Microevolution (You can see change)
I.


Evolution on a small scale within a single
population
A change in generation-to-generation
gene frequency within a population.
Detecting Micro-evolutionary Change

WHY?
Mechanisms of micro-evolutionary change
A.
1.
2.
3.
4.
Mutation
Migration
Genetic Drift
Natural Selection
Example of Microevolution

The size of the sparrow (originally introduced
in the East in 1852…)
Why are sparrows now larger in the north?
http://evoled.dbs.umt.edu/images/modes.gif
Speciation
II.

a lineage-splitting event that produces two
or more separate species
A.

Species
a group of individuals that actually or
potentially interbreed in nature.
•these happy face
spiders look different, but
since they can
interbreed, they are
considered the same
species: Theridion
grallator.
The scene: a population of wild fruit flies minding its own
business on several bunches of rotting bananas, cheerfully laying
their eggs in the mushy fruit...
Disaster strikes: A hurricane washes the bananas and the
immature fruit flies they contain out to sea.
The banana bunch eventually washes up on an island off the coast
of the mainland.
The fruit flies mature and emerge from their slimy nursery onto the
lonely island.

Has speciation occurred yet???
Types of Reproductive Isolation
(behavioral, geographic, temporal,
mechanical… pre/post zygotic???
So we meet again: When another storm
reintroduces the island flies to the
mainland… what will happen now?
Prezygotic Barriers
B.

1.
2.
3.
4.
5.
6.
Prevents mating and formation of zygotes
Habitat Isolation
Behavioral Isolation
Temporal Isolation
Mechanical Isolation
Gametic Isolation
Geographic Isolation
Postzygotic barriers
C.

1.
2.
3.
Prevents zygotes from developing into
fertile offspring
Reduced hybrid viability
Reduced hybrid fertility
Natural selection
Macroevolution
III.


evolution of groups larger than an
individual species.
encompasses the grandest trends and
transformations in evolution, such as the
origin of mammals and the radiation of
flowering plants

The basic evolutionary mechanisms—





mutation,
migration,
genetic drift, and
natural selection—
can produce major evolutionary change if
given enough time.
The History of Evolutionary Thought
A. James Hutton 17261797
1.
2.
Geologist
Gradualism

= Profound change is
the cumulative
product of slow but
continuous process
The History of Evolutionary Thought
 Geology


The scientific study of
the origin, history, and
structure of the earth
Geologic Time Scale

Used to represent
evolutionary time
Geology
The History of Evolutionary Thought
B. Charles Lyell (17971875)
Geologist
Uniformitarianism
1.
2.

Geological processes
have not changed
throughout Earth’s
history
The History of Evolutionary Thought
C. Jean Baptiste Lamark
(1744-1829)
Proposed theory of
evolution
1.
a.
b.
Change Through Use
and Disuse
Organisms Driven to
Greater Complexity
The History of Evolutionary Thought
D. Thomas Malthus (17661834)
1.
2.
Economist
Population Growth vs.
the Food Supply
The History of Evolutionary Thought
E. Charles Darwin
(1809-1882)
1.
2.
3.
Naturalist
1831-1836
voyage on
H.M.S. Beagle
Mission: chart
south american
coast line
F. Darwin’s Finches
1.
2.
3.
4.
5.
Galapagos formed
from volcanoes
(young)
Species live nowhere
else
Resemble South
American
Different islands,
different environments
Today – each island
has own species
6. Finch ancestors came from
South America
a.
“islands had been
colonized by plants and
animals strayed from
mainland and then
diversified”
7.Different islands, different
environments
a. Adaptation
G. Darwin’s Theory of
Natural Selection
1.
Obs. #1:

Population size
would increase
exponentially if all
offspring reproduced
successfully
2. Obs. #2:
Populations tend to
remain stable in size

3. Obs. #3:
Environmental resources
are limited

a.
Inf. #1: more individuals =
struggle for resources. Only
a fraction of offspring
survive
4. Obs. #4:

Individuals of a population vary
in characteristics
5. Obs. #5:

Much of variation is heritable
b.
Inf. #2: Survival is not random but depends
on heredity. Individuals most fit for
environment will produce more offspring
Inf. #3: unequal ability of individuals to
survive and reproduce = gradual change in
a population,
c.

with favorable characteristics accumulating over
generations
H. Key Subtle Points
1.
2.
3.
Individuals don’t evolve,
populations evolve
Adaptations an
organism acquires from
its own actions is
different from inherited
adaptations that evolve
in a population over time
Specifics of natural
selection are situational
Origin of Primates
Lemurs 55 mya
Tarsiers 50 mya … check out the
fingers…and massive eyes
New World Monkey (note tails, side
facing nostrils) 35 mya, all arboreal
Woolly spider monkey
golden lion tamarin
Old World monkey: ~22 mya (down
ward facing nostrils, no prehensile tail)
Some arboreal
Some ground dwelling
Macaque Monkey
Gibbon (ape not
a monkey) ~15 mya
Hominoids:
larger brains than
monkeys
no tails
smaller ranges
Hominoid: (ape) Orangutan diverged
~12 mya
Largest arboreal hominoid
Vegetarian
Gorilla (~8 mya) largest ape- live in
groups up to 20 individuals
Knuckle walkers
Can walk upright
Shorter legs than arms
Sexual dimorphism
More closely related to humans
and chimps than other apes
Pan paniscus, Pan troglodytes…
chimps… (diverged ~5 mya)
Bonobos chimps (dwarf chimpanzees)
(female dominate society)
regular chimpanzees (male
dominate society)
Human vs. Gorilla
Hominin family tree…
http://www.youtube.com/watch?v=w1Lu4VggDH0
Laetoli footpath
Lucy
3.6 mya
Evidence of bipedalism
Homo sapiens neanderthalensis vs
Homo sapiens sapiens
http://www.youtube.com/watch?v=doF4sNr
Qtmg&feature=related
Out of Africa… modern humans