Title: HISTORY OF LIFE
1HISTORY OF LIFE
2LAB this week FIELD TRIP
- Socks shoes (mud, poison ivy, briars)
- car pool (half an hour travel).
- Maps Wednesday.
- Hand-outs once you get there
- (2 pm/830 am).
- Nothing else to prepare.
3Want to Be a Chiropractor?
- Learn about some possibilities
- come here (WSB 209)
- 4 pm
- Tuesday
4reminder
- No quiz next Monday because .
5most important concept for Chapter 23
- Â Â Â Â
- Scientists' theories about species and speciation
are evolving, but natural selection in isolated
gene pools is still the main focus. - So Darwins theory is still the underlying
concept.
6Important points
- Speciation formation of a new species by
isolating part of a species from gene flow from
the old species - but what is a species?
7Table 23.1
8What is a species?
- Ideal types Before Darwin, scientists thought
of species as recognizable descendents of an
"ideal type" created by God, and even today
scientists often use "species" to mean a visibly
distinctive group of plants or animals
(morphospecies).
9Ideal types Not
- One of Darwins greatest contributions
- Variation is natural, not degenerate
10What is a species?
- Ideal types and morphospecies?
- Morphospecies differs from ideal type in that
genetic variation is expected. - After Darwin, scientists realized that many
species have so much genetic diversity it becomes
impossible to define the "ideal" or even
"typical" member.
11What is a species?
- As scientists learned more about genetics, they
began to define a species as all the members of a
gene pool. - (Biological species concept)
12What is a species?
- And as scientists learned more about evolutionary
details, they began to define a species as all
the members of a gene pool (Biological species
concept) with monophyletic ancestry - (phylogenetic species)
13Figure 23.2
B
C
D
E
F
G
H
J
I
A
14What is a species?
- From the only
- illustration in
- Darwins
- Origin of
- Species
15phylogenetic species?
- the trendy concept among taxonomists today
- Tree of Life web page
- Phylotree web page
- http//www.ucmp.berkeley.edu/alllife/
- but there are problems.
16Figure 23.10
Hybrids inherit species-specific mtDNA sequences
from their mothers.
Hybrids have intermediate characteristics.
Townsends warbler
All individuals have Townsends mtDNA
Some individuals have Townsends mtDNA, others
have hermit mtDNA
Townsends-hermit hybrid
Pacific Ocean
Hermit warbler
All individuals have hermit mtDNA
17Can a hybrid be a phylogenetic species?
B
C
D
E
G
H
J
I
A
F
18What is a species?
- its a fluid concept
- should we think of gene pools separating and
merging like bubbles so that you have a
phylo-web?
19Table 23.1
20Speciation requires isolation
- isolation of gene pools (always)
- change in genes (always)genetic change is caused
by - genetic drift in small gene pools usually
- natural selection usually
- mutations (including point and chromosomal)
usually
21Figure 23.8 left
DISPERSAL AND COLONIZATION
1. Start withone continuouspopulation.Then, a
colonistfloats to anisland on a raft.
Island
Continent
2. Finish withtwo populationsisolated fromone
another.
22Figure 23.8 right
VICARIANCE
1. Start withone continuouspopulation.Then a
chanceevent occursthat changesthe landscape
(river changes course).
River
2. Finish withtwo populationsisolated fromone
another.
River changes course
23Isolation in Allopatry is Spatial
- Allopatric speciation begins when sub-populations
become physically separated from each other. - Then divergent genetic changes accumulate.
-
24Isolation in Sympatry is Biological
- Sympatric speciation begins in populations that
occupy the same geographic area but become
reproductively isolated by a biological factor,
like food or a genetic change which affects
reproduction. - Then, with two gene pools, more changes evolve.
25Chapter 23
26Figure 23.5a
Beak length correlates with fruit size.
Balloon vine (native species)
Flat-poddedgolden rain tree(non-native species)
Short-beaked populationgrowing on
non-nativeplants
12
Long-beaked populationgrowing on native plants
8
4
0
Frequency
2
3
6
7
8
9
10
11
12
Beak length (mm)
8
Non-native plant(small fruit)
Native plant(large fruit)
4
0
2
3
6
7
8
9
10
11
12
Fruit radius (mm)
27Figure 23.6
Diploid parent
Tetraploid parent
(Four copies of each chromosome)
(Two copies of each chromosome)
Meiosis
Mating
Diploid gametes
Haploid gametes
(One copy of each chromosome)
(Two copies of each chromosome)
Triploid zygote
Meiosis
(Three copies of each chromosome)
When these gametes combine, most offspring have
incorrect number of chromosomes.
28Sympatric speciation is still a little
controversial
- Its often instant like polyploidy or even
smaller chromosomal mutations or even point
mutations affecting reproduction. - Its harder to understand unless you can imagine
many examples of reproductive isolation.
29Applying Darwin's ideas
- Did some skypilots inherit adaptations which
helped them survive and reproduce better than
others in a specific habitat?
30Figure 21.7 a,b
In tundra habitats above timberline, the alpine
skypilot is pollinated primarily by bumblebees.
28 24 20 16 12 8 4 0
Number of individuals
10 12 14 16 18 20 22
Tundra flower big and sweet-smelling
Flower size (mm)
In forested habitats below timberline, the alpine
skypilot is pollinated primarily by flies.
10
8
6
Number of individuals
4
2
0
10 12 14 16 18 20 22
Below-timberline flower small and
skunky-smelling
Flower size (mm)
31Applying Darwin's ideas
- Are skypilots diverging into separate species?
- Would this be an example of allopatry or sympatry?
32most important concept
- Â Â Â Â
- Scientists' theories about species and speciation
are evolving, but natural selection in isolated
gene pools is still the main focus. - Species and speciation are fluid concepts.
33most important concept for chapter 24
- Â Â Â Â Â
- DNA and the fossil record are the best evidence
for the history of the Earth. - So you need to know about
the DNA tools
34EVIDENCE WE CAN OBSERVE
- Extinctions
- fossils
- structural homologies
- developmental homologies
- genetic homologies
- vestigial traits
- changes in adaptations
- repeated patterns in all of the above
35History of Life on Earth
36Figure 24.4
Radiation of humans
Cambrian explosion
First multicellular organism
Earth forms
Origin of life
All life is unicellular
4.5
4.0
3.0
2.0
1.0
0
Today
Billions of years ago
Doushantuo fossils
Ediacaran fossils
Burgess shale fossils
600
550
500
Millions of years ago
37Box 24.1, Figure 2
H. sapiens
0
H. erectus H. ergaster
H. neanderthalensis (0.03-0.3 mya)
0.5
?
1.0
Time (millions of years ago)
H. heidelbergensis (0.2-0.6 mya)
H. habilis
1.5
H. rudolfensis
2.0
2.5
38Box 24.1, Figure 1
0.9
0.7
0.5
Percentage of amino acids in hemoglobin that are
different between species
0.3
0.1
Time (millions of years ago)
400
300
200
100
0
500
39Figure 24.11 b
Morphological diversity correlates with habitat
diversity.
Trunk/crown
Crown
Twig
Trunk/ground
Trunk/crown
Twig
Crown
Trunk/ground
HISPANIOLA
JAMAICA
40Figure 24.10
Star phylogeny
41Figure 24.9
(a) Early in development
FISH LIMB BUD
MOUSE LIMB BUD
(b) Later in development
Tail
Head
Tail
Head
(c) Hypothesis
Foot
Fin
Hoxd-11 expression along long axis of limb
Hoxd-11 expression as in fish,followed by
expression toward head
42Figure 24.1b
Permineralized The wood decayed very slowly,
allowing dissolved minerals to gradually
infiltrate the cells and then harden into stone.
Four types of Fossils
Compression Sediments accumulated on top of the
leaf and compressed it into a thin carbon-rich
film.
Cast The branch decomposed after it was buried.
Thisleft a hole that filled with dissolved
minerals,faithfully creating a cast of the
original.
Intact The pollen was preserved intact because
no decomposition occurred.
43(No Transcript)
44(No Transcript)
45Figure 24.5
1.
2.
3.
4.
46Figure 24.6 left
47Figure 24.6 right
48Figure 24.7 left
49Figure 24.7 right
50Figure 24.2 lower
4. The result.
Archaeopteryxthe first bird in the fossil record
51Mass Extinctions
- Biologists recognize five major mass extinction
events.We are likely in the middle of one now.
52Chapter 24
53Applying Darwin's ideas
- Are human races diverging into separate species?
- The book describes some interpretations of human
races. What is Freeman's point? - In your own opinion, why does it matter?
- Should we encourage research about genetic
differences among different ethnic groups
54http//www.sciencemag.org/cgi/content/full/291/550
9/1733
- By comparing data from maternally and paternally
inherited DNA, researchers are finding that in
our ancestral populations, men and women didn't
always travel together. In some cases, the genes
reveal how male explorers or warriors carried
their genomes to distant places. - (more story
next slide) - How do experiments tell the difference between
maternally and paternally inherited DNA?
55http//www.sciencemag.org/cgi/content/full/291/550
9/1733
- By comparing data from maternally and paternally
inherited DNA, researchers are finding that in
our ancestral populations, men and women didn't
always travel together. In some cases, the genes
reveal how male explorers or warriors carried
their genomes to distant places. - But surprisingly, in general females seem to have
stirred the genetic melting pot by dispersing
their DNA more widely than their brothers
dispersed theirs--perhaps as a result of
thousands of years of moving to join their
husbands' clans.
56Box 24.1, Figure 2
H. sapiens
0
H. erectus H. ergaster
H. neanderthalensis (0.03-0.3 mya)
0.5
?
1.0
Time (millions of years ago)
H. heidelbergensis (0.2-0.6 mya)
H. habilis
1.5
H. rudolfensis
2.0
2.5
57Oldest ancestral fossil found recently
- From
- Nature
- (free
- access)
58http//www.sciencemag.org/cgi/content/full/296/556
6/233
- In 1975, geneticist Mary-Claire King and the late
biochemist Allan Wilson, both then at the
University of California, Berkeley, showed that
the sets of proteins (and by extension, the genes
encoding the proteins' designs) found in
chimpanzees and humans were virtually identical.
That left open the question of how these two
species came to be so different (Science, 4
September 1998). - Wilson suggested then that the key might be
differences in gene expression, the rate at which
messenger RNA and proteins are made from a gene. - At long last, Pääbo and his colleagues have
experimental evidence that supports this
hypothesis.
59http//www.sciencemag.org/cgi/content/full/296/556
6/233
- Pääbo and his team at Max Planck Institute
collected brain, liver, and blood samples from
humans, chimps, macaques, and orangutans that had
died of natural causes. They isolated RNA from
each sample and passed it over a gene chip with
tags for 12,000 human genes. The more RNA
registered for a gene, the greater that gene's
activity. In a second experiment, they used a
membrane-based array to look at about 6000
additional genes. In each experiment, the
researchers studied RNA from chimps, humans, and
one of the other primates. - As expected, the researchers found little
difference among the species in the liver and
blood samples. - But in the brain, the species distinguished
themselves. The team detected big differences in
gene expression between humans and chimps,
whereas gene expression in the chimps' and the
other primates' brains was about the same.
60Last year http//www.sciencemag.org/cgi/content/fu
ll/298/5594/719b
- Comparison of an entire chromosome using gene
chips with 13 billion unique DNA fragments
http//www.scencemag.org/cgi/content/full/298/5594
/719b
61Last year http//www.sciencemag.org/cgi/content/fu
ll/298/5594/719b
- Comparison of an entire chromosome using gene
chips with 13 billion unique DNA fragments - MORE difference than expected, especially many
duplications, both coding and non-coding.
http//www.scencemag.org/cgi/content/full/298/5594
/719b
62 tomorrows news?
- Comparison of an entire genome using gene chips
with 13 billion unique DNA fragments ---gt 13
trillion RFLPs? - more chromosomes, more phylogenetic analyses.
- Differences in brains may be more hox genes?
- Naked ape hypothesis may be supported if analyses
show loss of other late-embryo genes? - ????
http//www.scencemag.org/cgi/content/full/298/5594
/719b
63 and other Highwire journals My search
criteriahuman evolution (exact phrase in title
or abstract) Jan 2002 through Oct 2003 24 hits
64Human-specific regulation of Alpha2-6 linked
sialic acids Molecular basis of the TaqI
p49a,f polymorphism in the DYS1 locus
containing... Equality for the sexes in
human evolution? Early hominid sexual dimorphism
a... Estimation of Species Divergence Times
and Ancestral Population Sizes ... Origins of
Psychopathology The Phylogenetic and Cultural
Basis of Mental Il... Evolutionary
relationships of the Tas2r receptor gene families
in mouse and ... Evidence for a genetic
discontinuity between Neandertals and
24,000-year-old... Novel Multilocus Measure of
Linkage Disequilibrium to Estimate Past
Effectiv... Least effort and the origins of
scaling in human language A Mind So Rare The
Evolution of Human Consciousness Intra-Deme
Molecular Diversity in Spatially Expanding
Populations Accelerated Protein Evolution and
Origins of Human-Specific Features FOXP2
... Evolutionary and Historical Aspects of
the Burden of Malaria Inactivation of
CMP-N-acetylneuraminic acid hydroxylase occurred
prior to br.. HUMAN EVOLUTION Can Selection
Explain the Presbyterians? Tracing the LINEs of
human evolution Human-specific Organization of
Primary Visual Cortex Alternating
Compartmen... HUMAN EVOLUTION Out of the
Chattering Ice Mind the gap--hierarchies, health
and human evolution Larger Genetic
Differences Within Africans Than Between Africans
and Eurasia... The Increase in Allergic
Respiratory Diseases Survival of the Fittest?
65Chapter 24
For more, seehttp//campus.queens.edu/faculty/jan
nr/evolution.htm
66Mechanisms of Evolutionary Change
- Evolution is defined as a change in allele
frequencies over time. - Natural selection acts on individuals, but
evolutionary change occurs in populations.
67Darwin's concept
- Natural Selection survival and reproduction of
the fittest. - Also Adaptive Radiations now also called star
phylogenies
68Figure 21.7 a,b
In tundra habitats above timberline, the alpine
skypilot is pollinated primarily by bumblebees.
28 24 20 16 12 8 4 0
Number of individuals
10 12 14 16 18 20 22
Tundra flower big and sweet-smelling
Flower size (mm)
In forested habitats below timberline, the alpine
skypilot is pollinated primarily by flies.
10
8
6
Number of individuals
4
2
0
10 12 14 16 18 20 22
Below-timberline flower small and
skunky-smelling
Flower size (mm)
69Figure 22.9b
For example, only juvenile blackbellied
seedcrackers with very longor very short beaks
survived long enough to breed.
30
20
Number of individuals
10
0
11
6
7
10
8
9
Beak length (mm)
70Figure 23.1
Large ground finch
Small ground finch
71Darwin's four postulates
- Individuals have variations
- Variations are genetic
- only some offspring survive and reproduce
- Natural Selection survival and reproduction of
the fittest.
72MORE ABOUT
- Darwin http//www.queens.edu/faculty/jannr/darwin.
htm - Creationism
- http//www.queens.edu/faculty/jannr/creationism.ht
m - Evolution
- http//www.queens.edu/faculty/jannr/evolution.htm
73 Preview of Wednesdays Assignment
- Â Â Â Â Â
- http//www.queens.edu/faculty/jannr/bio103/helpPa
ges/c47behavior.htm