Colonie High AP Biology DeMarco/Goldberg

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

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…

Colonie High AP Biology DeMarco/Goldberg

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

Hyracotherium Mesohippus

Merychippus

Nannippus

Bo

dy

siz

e (

kg

)

Evolution of Birds

Smithsonian Museum,

Washington, DC

Archaeopteryx

lived about 150 mya

links reptiles & birds ?

?

?

?

Land Mammal

Vestigial Organs Hind leg bones on whale fossils

Anatomical Record

Homologous structures

similarities in characteristics resulting

from common ancestry

Colonie High AP Biology DeMarco/Goldberg

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

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

Convergent Evolution

Flight evolved in 3 separate animal groups

evolved similar “solution” to similar

“problems”

analogous structures

Convergent Evolution

Fish: aquatic vertebrates

Dolphins: aquatic mammals

similar adaptations to

life in the sea

not closely related

Colonie High AP Biology DeMarco/Goldberg

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 Placental Mammals Australian Marsupials

Burrower Mole

Anteater

Mouse

Lemur

Flying squirrel

Ocelot

Wolf Tasmanian “wolf”

Tasmanian cat

Sugar glider

Spotted cuscus

Numbat

Marsupial mole

Marsupial mouse

Anteater

Nocturnal insectivore

Climber

Glider

Stalking predator

Chasing predator

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

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 75 100 125 0

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

cle

oti

de s

ub

sti

tuti

on

s

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

cytochrome c from 33 species

Colonie High AP Biology DeMarco/Goldberg

Comparative Hemoglobin Structure

10 0 20 30 40 50 60 70 80 90 100 110 120

Lamprey Frog Bird Dog Macaque Human

32 8 45 67 125

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 divergance

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

Colonie High AP Biology DeMarco/Goldberg

Phylogenetic Trees Plant Diversity

Bryophytes

non-vascular

land plants

Pteridophytes

seedless

vascular plants

Gymnosperm

pollen &

“naked” seeds

Angiosperm

flowers & 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 vertebrates segmented

worms insects spiders

backbone

protostomes deuterostomes

synapomorphies

synapomorphies

Evidence of Evolution

by Natural Selection

Testable Hypotheses

Peppered Moths

Dark vs. light variants

Year % dark % light

1848 5 95

1895 98 2

1995 19 81

Colonie High AP Biology DeMarco/Goldberg

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

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) 48

gorilla (Gorilla) 48

chimpanzee (Pan) 48

human (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 Fusion

Testable 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) 48

gorilla (Gorilla) 48

chimpanzee (Pan) 48

human (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.”

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

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