Chapter 24/25 Evidence of Evolution

Geological, Anatomical, Chemical, Molecular

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 the wolf

“descendants” of wild mustard

‘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

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”

Geologist give us time for evolution…

Fossil Record A record showing us that today’s

organisms descended from ancestral species

Evolutionary Change In Horses

Millions of years ago

50

100

150

200

250

300

350

400

450

500

550

60 55 50 45 40 35 30 25 20 15 10 5 0

Equus

HyracotheriumMesohippus

Merychippus

Nannippus

Bo

dy

siz

e (

kg

)

Evolution of Birds

Smithsonian Museum, Washington, DC

Archaeopteryx lived about 150 mya links reptiles & birds

??

??Where are the

Intermediates?

Land Mammal

Vestigial Organs Hind leg bones on whale fossils

Why would whaleshave pelvis & leg bones

if they were alwayssea 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

Solving a similar problem with a similar solution

Don’t be fooledby their looks!

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?

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 Parallel, but separate, evolutionary paths

filling similar ecological roles in similar environments, so similar adaptations were selected

but are not closely related

marsupial mammalsmarsupial mammals

placental mammal

s

placental mammal

s

Parallel EvolutionNiche 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

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

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

Nu

cleo

tid

e su

bst

itu

tio

ns

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

DNA & proteins are a molecular record of evolutionary relationships

Why comparethese genes?

cytochrome c from 33 species

Comparative Hemoglobin Structure

100 20 30 40 50 60 70 80 90 100 110 120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans

Why does comparingamino acid sequencemeasure evolutionary

relationships?

Globin Gene Family Tree looking at the DNA sequences of the different globins can show approximate time of divergence

Evidence of Evolutionby 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)

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?

Chromosomal FusionTestable prediction:

If common ancestor had 48 chromosomes (24 pairs),then humans carry a fused chromosome (23 pairs).

Centromere

Telomere

Ancestral Chromosomes Fusion Homo sapiens

Inactivated centromere

Telomere sequences

Chromosome Number in the Great Apes

(Hominidae)

orangutan (Pogo)

48gorilla (Gorilla)

48chimpanzee (Pan)

48human (Homo)

46

Testing 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 acrocentric 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.”

“Chromosome 2 is unique to the human lineage of evolution, having emerged as a result of head-to-head fusion of two acrocentric 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.

Human Chromosome #2 shows the exact point at which this

fusion took place…

Chr 2

Ancestral Chromosomes Fusion Homo sapiens

Inactivated centromere

Telomere sequences

Well I’llbe a monkey’s…or an ape’s…uncle? Cousin?

Wait – what does this mean?

In case you had any doubts…

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

Building “Family” Trees Closely related species (branches) share same line of descent until their divergence from a common ancestor more like evolutionary “bushes”

Archaebacteria&

Bacteria

Classification Old 5 Kingdom system

Monera Protists Plants Fungi Animals

New 3 Domain system Bacteria Archaebacteria Eukaryotes

Protists Plants Fungi Animals

Prokaryote

Eukaryote

Linnaen Nesting

KPCOFGS not used so

much more as phylogenetics developed

Phylogenetic Trees

Plant Diversity

Bryophytesnon-

vascularland plants

Pteridophytesseedless vascular plants

Gymnospermpollen & “naked” seeds

Angiospermflowers &

fruit

seed plants

vascular plants

mosses ferns

conifers flowering plants

colonization of land

synapomorphies

Cnidaria

Platyhelminthes

sponges jellyfish flatworms roundworms

Nematoda

Mollusca Arthropoda Chordata

Annelida Echinoderm

mollusks

multicellularity; diploblastic

Ancestral Protist

tissues

bilateral symmetry; triploblastic

body cavity

segmentation

Porifera

Animal Diversity

coelom

starfish vertebratessegmentedworms

insectsspiders

backbone

protostomes deuterostomes

synapomorphies

synapomorphies

Any Questions??

put peppered moth in lab 17

Peppered Moths Dark vs. light variants

Year % dark % light1848 5 951895 98 21995 19 81

Peppered Moths 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