Transcript Ch22--Evidence for Evolution v2015x

Chapter 22
Evidence of Evolution
& Phylogenetics
Dodo bird
Evidence Supporting Evolution
 Artificial selection

human-caused evolution
 Fossil record

transition species
 Anatomical record
homologous & vestigial structures
 embryology & development

 Molecular record

protein & DNA sequence
Artificial Selection
 Artificial breeding can use variations in
populations to create vastly different
“breeds” & “varieties”
“descendants”
of wild mustard
“descendants”
of the wolf
‘Natural’ Selection in Action
 Insecticide &
drug resistance
insecticide didn’t
kill all individuals
 resistant survivors
reproduce
 resistance is
inherited
 insecticide
becomes less &
less effective

Fossil Record
 Layers of sedimentary rock contain fossils
new layers cover older ones, creating a
record over time
 fossils within layers show that a succession
of organisms have populated Earth
throughout a long period of time

Fossil Record
Geologist give us time for evolution…
 Charles Lyell (1797-1875)
studied the Temple of Scrapis (Sicily)
 built on land & used until 200 AD
 high tide now above temple floor
 erosion in columns well above high tide

Meaning:
In less than 2000 years, temple
sunk well below sea level, and then
was raised up again — natural
processes and immense periods of
time could produce great changes.
“the present is the key to the past”
Fossil Record
 A record showing us that today’s
organisms descended from ancestral
species
Evolutionary Change In Horses
550
500
Body size (kg)
450
Equus
400
350
300
250
Merychippus
200
150
Mesohippus
Hyracotherium
100
50
Nannippus
60 55 50 45 40 35 30 25 20 15 10 5 0
Millions of years ago
Evolution of Birds
 Archaeopteryx


lived about 150 mya
links reptiles & birds
Smithsonian Museum,
Washington, DC
Land Mammal
?
?
?
?
Vestigial Organs
 Hind leg bones on whale fossils
Why would whales
have pelvis & leg bones
if they were always
sea creatures?
Vestigial Organs
 Modern animals may have structures
that serve little or no function
remnants of structures that were
functional in ancestral species
 evidence of change over time

 some snakes & whales show remains of the
pelvis & leg bones of walking ancestors
 eyes on blind
cave fish
 human tail bone
This is not
LaMarck’s loss
from “disuse”!
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
Homologous Structures
 Forelimbs of human, cats, whales, & bats
share same skeletal structures
similar structure
 similar embryological development
 different functions
 evidence of common ancestor

 branched off from
common 4-limbed
ancestor
2006 Fossil Discovery of Early Tetrapod
 “missing link” from sea to land animals
YOUR INNER FISH!
Analogous Structures
 Separate evolution of structures
similar functions
 similar external form
 different internal structure &
development
 different origin
 no evolutionary relationship

Don’t be fooled
by their looks!
Solving a similar problem with a similar solution
Convergent Evolution
 Flight evolved in 3 separate animal groups
evolved similar “solution” to similar
“problems”
 analogous structures

Does this mean
they have a
recent common
ancestor?
Those fins & tails
Convergent Evolution
& sleek bodies are
analogous structures!
 Fish: aquatic vertebrates
 Dolphins: aquatic mammals
similar adaptations to
life in the sea
 not closely related

Parallel Evolution
 Parallel, but separate, evolutionary paths
filling similar ecological roles in similar
environments, so similar adaptations were
selected
 but are not closely related

marsupial
mammals
placental
mammals
Parallel Evolution
Niche
Burrower
Placental Mammals
Australian Marsupials
Mole
Marsupial mole
Anteater
Numbat
Anteater
Nocturnal
insectivore
Mouse
Climber
Marsupial mouse
Spotted cuscus
Lemur
Glider
Stalking
predator
Chasing
predator
Sugar glider
Flying
squirrel
Ocelot
Tasmanian cat
Wolf
Tasmanian “wolf”
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.
Molecular Record
 Comparing DNA & protein structure

universal genetic code!
 DNA & RNA

Why compare
these genes?
compare common genes
 cytochrome C (respiration)
 hemoglobin (gas exchange)
Human/kangaroo
 DNA & proteins are a molecular
record of evolutionary
relationships
Nucleotide substitutions
Closely related species have
sequences that are more
similar than distantly related
species
100
Dog/
cow
75
Human/
cow
Rabbit/
rodent
50 Horse/
donkey
Llama/
cow
Horse/cow
Sheep/
goat
25
Human/rodent
Pig/
cow
Goat/cow
0
0
25
50
75
100
Millions of years ago
125
cytochrome c from 33 species
Comparative Hemoglobin Structure
Human Macaque
Dog Bird
Frog
Lamprey
32 45
67
125
Why does comparing
amino acid sequence
measure evolutionary
relationships?
8
0 10 20 30 40 50 60 70 80 90 100 110 120
Number of amino acid differences between
hemoglobin (146 aa) of vertebrate species and that of humans
Globin Gene Family Tree
 looking at the DNA sequences of the
different globins can show approximate time
of divergence
Evidence of Evolution
by Natural Selection
Using Molecular
Evidence to check
Testable Hypotheses
Genome Sequencing
 What can data from whole
genome sequencing tell us
about evolution of humans?
Primate Common Ancestry?
Chromosome Number
in the Great Apes
(Hominidae)
orangutan (Pogo)
gorilla (Gorilla)
chimpanzee (Pan)
human (Homo)
48
48
48
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?
Chromosomal Fusion
Testable prediction:
If common ancestor had 48 chromosomes (24 pairs),
then humans carry a fused chromosome (23 pairs).
Ancestral
Chromosomes
Fusion
Chromosome Number
in the Great Apes
(Hominidae)
orangutan (Pogo)
gorilla (Gorilla)
chimpanzee (Pan)
human (Homo)
Homo sapiens
Inactivated
centromere
Telomere
sequences
48
48
48
46
Centromere
Telomere
Testing the Human Genome
Hillier et al (2005) “Generation and Annotation of the DNA
sequences of human chromosomes 2 and 4,” Nature 434: 724 – 731.
Ancestral
Chromosomes
Fusion
Homo sapiens
Inactivated
centromere
Telomere
sequences
Chr 2
“Chromosome 2 is unique to the human
lineage of evolution, having emerged as a
result of head-to-head fusion of two
acrocentric chromosomes
Well I’ll that remained
separate inbe
other
primates. The precise
a monkey’s
fusion site has
located in 2q13–
…orbeen
an ape’s…
2q14.1, where our analysis confirmed the
uncle? Cousin?
presence of multiple subtelomeric
Wait
– what 1, 5, 8, 9, 10,
duplications
to chromosomes
12, 19, 21 and 22. During the formation of
does this mean?
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.”
Human Chromosome #2 shows
the exact point at which this
fusion took place…
On the left is a copy
of the human
chromosome ‘set’.
On the right is the
respective
chromosome for
the chimpanzee—
our nearest cousin
outside our
species
In case you had any doubts…
Building “Family” Trees
 Closely related species (branches) share
same line of descent until their divergence
from a common ancestor
 more like evolutionary “bushes”
Eukaryote
Classification
 Old 5 Kingdom system





Monera
Protists
Plants
Fungi
Animals
Prokaryote
 New 3 Domain system
 Bacteria
 Archaebacteria
 Eukaryotes
 Protists
 Plants
 Fungi
 Animals
Archaebacteria
&
Bacteria
Linnaen Nesting
 KPCOFGS
 not used so
much more as
phylogenetics
developed
Phylogenetic Trees
Plant Diversity
Bryophytes
non-vascular
land plants
Pteridophytes
seedless
vascular plants
Gymnosperm
pollen &
“naked” seeds
conifers
mosses
Angiosperm
flowers & fruit
flowering plants
ferns
seed plants
vascular plants
synapomorphies
colonization of land
Animal Diversity
Cnidaria
Porifera
sponges
jellyfish
Nematoda
Platyhelminthes
Annelida
Mollusca
Echinoderm
Arthropoda
segmented
flatworms roundworms mollusks
worms
insects
spiders
starfish
vertebrates
backbone
segmentation
protostomes
Chordata
coelom
deuterostomes
body cavity
bilateral symmetry; triploblastic
tissues
multicellularity; diploblastic
Ancestral Protist
synapomorphies
synapomorphies
Any Questions??