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Evidence of Evolution by Natural Selection (Ch. 22). Dodo bird. Evidence supporting evolution. Fossil record Anatomical record Molecular record Artificial selection. Fossil record. Layers of sedimentary rock contain fossils new layers cover older ones, creating a record over time - PowerPoint PPT Presentation
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Evidence of Evolutionby Natural Selection
(Ch. 22)
Dodo bird
Evidence supporting evolution• Fossil record• Anatomical record• Molecular record• Artificial selection
Fossil record• Layers of sedimentary rock contain fossils
– new layers cover older ones, creating a record over time
– Show that a succession of organisms have populated Earth throughout a long period of time
Formation of sedimentary strata containing fossils
1 Rivers carry sediment to the ocean. Sedimentary rock layers containing fossils form on the
ocean floor.2 Over time, new strata are
deposited, containing fossils from each time period.
3 As sea levels change and the seafloor is pushed upward, sedimentary rocks are
exposed. Erosion reveals strata and fossils.
Younger stratum with more recent
fossils
Older stratum with older fossils
A gallery of fossil types
(a) Dinosaur bones being excavated from sandstone
(g) Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice
(e) Boy standing in a 150-million-year-old dinosaur track in Colorado
(d) Casts of ammonites, about 375 million
years old
(f) Insects preserved whole in amber
(b) Petrified tree in Arizona, about 190 million years old
(c) Leaf fossil, about 40 million years old
Support (proof?) for a VERY old Earth.
A dragonfly fossil from Brazil, more than 100 million years old
The Geologic Record
Evolutionary change in horses
Millions of years ago
50
100
150
200250
300
350
400
450
500
550
60 55 50 45 40 35 30 25 20 15 10 5 0
Equus
HyracotheriumMesohippus
Merychippus
Nannippus
Bod
y si
ze (k
g)
Evolution of birds
Smithsonian Museum, Washington, DC
• Archaeopteryx– lived about 150 mya– links reptiles & birds
??
??Where are the
transitional
fossils?
Land Mammal
Whales, you ask...
A transitional fossil linking past and present
Oh. Here they
Are!
2006 Fossil Discovery of Early Tetrapod• Tiktaalik
– “missing link” from sea to land animals
Anatomical record• Homologous structures
– similarities in characteristics resulting from common ancestry
Homologous structures• Similar structure• Similar development• Different functions • Evidence of close
evolutionary relationship– recent common ancestor
spines
tendrilssucculent leaves
colored leaves
Homologous structures
leaves
needles
Analogous structures Separate evolution of structures
similar functions similar external form different internal structure & development different origin no evolutionary relationship
Solving a similar problem with a similar solution
Don’t be fooledby their looks!
Convergent evolution• Flight evolved in 3 separate animal groups
– analogous structures
Does this mean they have a
recent common ancestor?
Convergent evolution of analogous burrowing characteristics
Convergent evolution Fish: aquatic vertebrates Dolphins: aquatic mammals
similar adaptations to life in the sea
not closely related
Those fins & tails & sleek bodies are
analogous structures!
Parallel Evolution• Convergent evolution in common niches
– Similar ecological roles in similar environments, Similar adaptations were selected
– but are not closely related
marsupial mammals
placental mammals
Parallel types across continentsNiche Placental Mammals Australian Marsupials
BurrowerMole
Anteater
Mouse
Lemur
Flyingsquirrel
Ocelot
Wolf Tasmanian “wolf”
Tasmanian cat
Sugar glider
Spotted cuscus
Numbat
Marsupial mole
Marsupial mouse
Anteater
Nocturnalinsectivore
Climber
Glider
Stalkingpredator
Chasingpredator
Vestigial organs• Structures that serve little or no function
– remnants of structures that were functional in ancestral species
– deleterious mutations accumulate in genes for non-critical structures without reducing fitness• snakes & whales — remains of pelvis & leg
bones of walking ancestors• eyes on blind cave fish• human tail bone
This is not LaMarck’s loss from “disuse”!
Vestigial organs• Hind leg bones on whale fossils
Why would whaleshave pelvis & leg bones
if they were alwayssea creatures?
Comparative embryology• Similar embryological development in closely
related species– all vertebrate embryos have similar structures at
different stages of development • gill pouch in fish, frog, snake, birds, human, etc.
Anatomical similarities in vertebrate embryos
Pharyngealpouches
Post-analtail
Chick embryo Human embryo
Molecular record
0 25 50 75 100 1250
25
50
75
100
Millions of years ago
Horse/donkey
Sheep/goat
Goat/cow
Llama/cow
Pig/cow
Rabbit/rodent
Horse/cow
Human/rodent
Dog/cow
Human/cow
Human/kangaroo
Nuc
leot
ide
subs
titut
ions
• Comparing DNA & protein structure– universal genetic code!
• DNA & RNA– compare common genes
• cytochrome C (respiration)• hemoglobin (gas exchange)
Closely related species have sequences that are more similar than distantly related species A molecular record of evolutionary
relationships
Why comparethese genes?
Comparison of a protein found in diverse vertebrates
Species
Human
Rhesus monkey
Mouse
Chicken
Frog
Lamprey14%
54%
69%
87%
95%
100%
Percent of Amino Acids That AreIdentical to the Amino Acids in aHuman Hemoglobin Polypeptide
Comparative hemoglobin structure
Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans
100 20 30 40 50 60 70 80 90 100 110 120
LampreyFrogBirdDogMacaqueHuman
328 45 67 125
Why does comparingamino acid sequencemeasure evolutionary
relationships?
Building “family” treesClosely related species (branches) share same line of descent until their divergence from a common ancestor
Artificial selection• Artificial breeding can use variations in
populations to create vastly different “breeds” & “varieties”
“descendants” of the wolf“descendants” of wild mustard
It’s Important To Remember How Powerful And Fast Selection Can Be!!!
Natural selection in action
• Insecticide & drug resistance– insecticide doesn’t
kill all individuals– resistant survivors
reproduce– resistance is
inherited– insecticide becomes
less & less effective
Evolution of drug resistance in HIV
PatientNo. 1
Patient No. 2
Patient No. 3
Per
cent
of H
IV re
sist
ant t
o 3T
C
Weeks
Evolution MisconceptionsA Brief Discussion
“if we came from apes how come were not hairy and have a big mouth and did we end up looking like we do know and besides there isnt any serious proof of apes they showd a video saying an ape waswondering around in the forest that thing looked exactly like a costume that i had saw at a store know one ever cought an ape”
-From a post on the Internet
NOT THIS KIND!!!(beyond help)
The Complexity Fallacy
Don’t Get Lazy!This Isn’t How It
Happens!!!
Evolution is not goal-orientedAn evolutionary trend does not mean that evolution is goal-oriented.
Surviving species do not represent the peak of perfection. There is compromise & random chance involved as well
Remember that for humans as well!
Evolution is not the survival of the fittest.
Rather it is the survival of the just
good enough.
Unintelligent Design
Serial circulation in the mammalian heart
"Nothing in biology makes sense except
in the light of evolution."
-- Theodosius DobzhanskyMarch 1973
Geneticist, Columbia University(1900-1975)
-- Ernst Mayr What Evolution Is
2001Professor Emeritus, Evolutionary Biology
Harvard University(1904-2005)
Evolution is "so overwhelmingly established that it has become
irrational to call it a theory."
I might be dead, but Perhaps you children
would appreciate a bit of what you call the “rap”
music?!?
Don’t BeUnintelligent...
Ask Questions!!
Evidence of Evolutionby Natural SelectionTestable Hypotheses
(Ch. 22- 24)
Just Because Things Seem Obvious
Doesn’t Mean They Don’t Need To Be Supported
Peppered Moths• Dark vs. light variants
Year % dark % light1848 5 951895 98 21995 19 81
Peppered moth• What was the selection factor?
– early 1800s = pre-industrial England• low pollution• lichen growing on trees = light colored bark
– late 1800s = industrial England• factories = soot coated trees• killed lichen = dark colored bark
– mid 1900s = pollution controls• clean air laws• return of lichen = light colored bark
– industrial melanism
Genome sequencing• What can whole genome
sequence data tell us about evolution of humans?
Primate Common Ancestry?Chromosome Number in
the Great Apes (Hominidae)
orangutan (Pogo) 48gorilla (Gorilla) 48chimpanzee (Pan) 48human (Homo) 46
Hypothesis:Change in chromosome number? If these organisms share a common ancestor, then is there evidence in the genome for this change in chromosome number
Could we have just lost a pair ofchromosomes?
Chromosomal fusionTestable prediction: If common ancestor had 48 chromosomes (24 pairs),then humans carry a fused chromosome (23 pairs).
CentromereTelomere
Ancestral Chromosomes Fusion Homo sapiens
Inactivated centromere
Telomere sequences
Chromosome Number in the Great Apes
(Hominidae)
orangutan (Pogo) 48gorilla (Gorilla) 48chimpanzee (Pan) 48human (Homo) 46Testable!
This is what makes evolution science
& not belief!
Test of the Human Genome“Chromosome 2 is unique to the human lineage of evolution, having emerged as a result of head-to-head fusion of two chromosomes that remained separate in other primates. The precise fusion site has been located in 2q13–2q14.1, where our analysis confirmed the presence of multiple subtelomeric duplications to chromosomes 1, 5, 8, 9, 10, 12, 19, 21 and 22. During the formation of human chromosome 2, one of the two centromeres became inactivated (2q21, which corresponds to the centromere from chimp chromosome 13) and the centromeric structure quickly deterioriated.”
Hillier et al (2005) “Generation and Annotation of the DNA sequences of human chromosomes 2 and 4,” Nature 434: 724 – 731.
Chr 2
Ancestral Chromosomes Fusion Homo sapiens
Inactivated centromere
Telomere sequences
Human Chromosome #2 shows the exact point at which this fusion took place
Well I’llbe a monkey’s…or an ape’s…
uncle!
Geographic variation in chromosomal mutations
1 2.4 3.14 5.18 6 7.15
XX1913.1710.169.128.11
1 2.19 3.8 4.16 5.14 6.7
XX15.1813.1711.129.10
2007-2008
Any Questions??
Review Questions
1. A complete fossil record1. Exists because of the great preservation in
ocean sediment2. Exists because of the solidification of minerals
around organisms3. Is available because of the small location in
which all organisms used to live4. Exists because organisms that die become
embedded in the soil to form rocks5. Does not exist.
2. The similarity of insect wings and bird wings is an example ofA. Behavioral adaptationsB. Geographic isolationC. Adaptive radiationD. Convergent evolutionE. Divergent evolution
3. The human appendix is an example of1. A balanced polymorphism2. Divergent evolution3. Convergent evolution4. A vestigial structure5. A homologous structure
4. One piece of evidence that supports evolution from molecular biology is:1. Carbohydrate structure2. Amino acid sequences3. Lipid composition4. Nucleotide structure5. Cellulose chains