Evidence of Evolution

Evidence for Evolution

Unit7.Lesson6

VIDEO- How Evolution Works (And how we figured it out)

Darwin found evidence from

several sources

Evidence for evolution:

● Fossils

● Geography

● Embryology

● Comparative Anatomy

● DNA (molecular biology)

Fossils

● Fossils are remains of ancient

organism found in layers of
rock

● Darwin viewed the fossil

record and proposed that
countless species of many
different forms had appeared
on Earth, lived for a time and
vanished.

Fossils

Multiple Choice

Fossils are...

• Remains of ancient organisms found in layers of rock

• Remains of Plants and Animals that exist on Earth

• Abiotic Evidence of criminal activity

• Dead Things

Fossil Record

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•Layers of rock

tell the history of
Earth
•Fossils are
thought to be the same age
as the rock they are found
in

Multiple Choice

Fossils are thought to be _______ as the rock around them

• Older

• Younger

• The same age

• Made of

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KT Boundary

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Fossils

●Darwin found fossils of extinct animals that resemble

modern animals

●The fossil record shows change over time!

Ice Age!

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Fossils: Transitional Fossils

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● Transitional fossils are fossils that exhibit traits

common to an ancestral group and its descendant
group

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Fossils: Transitional Fossils

Fossils: Transitional Fossils

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● Tiktaalik-

intermediate between
fish an early tetrapods

● Fins have a basic wrist

bone and simple
fingers

● Earliest fish with a

neck

Multiple Choice

Transitional fossils...

• exhibit genes from neighboring groups

• show how organisms survived mass extinction

• exhibit traits common to ancestral group

• are made of transitional metals

Fossils: Divergent Evolution

● We can expect to find closely related

yet different species living in a
geographic region as they spread into
nearby habitats and evolve (divergent
evolution= adaptive radiation)

● EXAMPLE: Galapagos tortoises and

finches adapted to different habitats as
they spread from the mainland to the
different islands.

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Multiple Choice

Which is an example of Divergent Evolution?

• Trees and Mushrooms live on the ground because they eat the same food

• Sharks and Whales look similar because they live in the same habitat

• Birds and Mosquitos can fly because they both have wings.

• Elephants and Wolly Mammoths are different species, but share a common ancestor.

Fossils: Convergent Evolution

● We can expect to find different species living

in far apart geographic regions but similar
habitats becoming more alike as they adapt to
similar ecosystem (convergent evolution)

● EXAMPLE: Whales and sharks have a similar

body design even though they are very
different organisms (one is a fish; the other a
mammal). They have independently adapted to
living in a similar environment.

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Multiple Choice

Which is an example of Convergent Evolution?

• Cats and Dogs are best friends.

• Dragonflies and Birds can fly because they have similar survival strategies, in similar habitats

• Whales and Dogs both breath atmospheric oxygen, because they are mammals.

• Humans and Raccoons both have thumbs because they share a common ancestor

Geography

Geography

● The study of geography provides evidence of evolution:

○ Darwin observed that island species most closely resembled

nearest mainland species

○ Darwin decided that populations can show variation from one

island to another due to descent with modification

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Embryology

Embryology

● Embryology is the study of embryos

● Embryology provides evidence of evolution:

○ Identical larvae, different adult body forms

○ Similar embryos, diverse organisms

Larva

Adultbarnacle

Adult crab

Barnacles

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Embryology

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Multiple Choice

Embryos that share a common ancestor are...

• similar

• different

• colorful

• confusing

Comparative Anatomy

Comparative Anatomy

● Anatomy is the study of body structures in

organisms

● Anatomical structural patterns are clues to the

history of a species

○ Homologous structures Homo= Same
○ Analogous structures A or An= Not
○ Vestigial structures Vestige= Footprint

Homologous Structures

● Homologous structures are similar in structure but different

in function

● Homologous structures ARE evidence of a common ancestor

(evolution)

Homologous structures

Human hand

Batwing

Molefoot

Multiple Choice

Homologous structures are...

• different in function and structure

• similar in function, but different in structure

• similar in function and similar in structure

• similar in structure, but different in function

Human hand

Bat wing

Mole foot

Fly wing

Analogous Structures

● Analogous structures are similar in function but different

in structure

● Analogous structures are NOT evidence of a common

ancestor

● Example: fly wing and a bat wing

Multiple Choice

Analogous structures are...

• different in function and structure

• similar in function, but different in structure

• different in function, but similar in structure

• similar in function and structure

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Vestigial structures are remnants of organs or
structures that had a function in an early ancestor

• EXAMPLES:

• Ostrich wings
• Human appendix

Vestigial Structures

Vestigial Structures: Skinks

● Skinks are a type of lizard

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Vestigial Structures: Skinks

● In some species, the legs have become so small they no

longer function in walking

● Why would an organism possess organs with little or no

function? The gene code is present to makes the
organ, but function has been lost over time. If the
organ is vital to survival, then natural selection would
not cause its elimination.

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Vestigial Structures: Vestigial

Genes

● Do you ever wonder why dogs and cats don't need to eat

fresh fruit, but you do?

● Fish, amphibians, reptiles and most mammals can make their

own Vitamin C
○ Humans cannot and need to eat fresh fruit or they might

develop scurvy

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Vestigial Structures:

Vestigial Genes

● Human DNA contains the gene that codes for the enzyme

to make Vitamin C, but it's nonfunctional- these are called
vestigial genes

● Guess what other group of organisms lack the ability to

make their own Vitamin C?

○ PRIMATES… chimpanzees, orangutans, gorillas and other

apes

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Vestigial Structures: Vestigial Genes

● Humans have many other nonfunctional vestigial

genes called pseudogenes

● Example: Humans have more than 99 different odor

receptors, but more than 70% are nonfunctional

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Multiple Choice

Who can make Vitamin C?

• Fish, amphibians, reptiles, and mammals

• All animals except Mammals.

• Fish, amphibians, reptiles and mammals... except for Humans

• Fish, amphibians, reptiles and mammals... except for humans and primates.

DNA

(Molecular Biology)

•

Similarities in DNA and protein sequences suggest

relatedness

DNA

● If you take the two smaller

chimpanzee chromosomes, that
humans don’t have, and place them
end to end… the banding pattern is
identical to the #2 human
chromosomes!

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DNA: Human Chromosome #2

● Chromosomes have special end sequences

called telomeres

● Telomere sequences are found at the ends

and also IN THE MIDDLE of human
chromosome #2

○ Suggesting that it was made by fusing two

other chromosomes together

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DNA: Human Chromosome #2

● Chromosomes have special sections, called

centromeres, where spindle fibers will attach
during mitosis

● Human chromosome #2 has an inactive

centromere region

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DNA: Human Chromosome #2

DNA: Cytochrome C

● Cytochrome c is part of the electron transport

chain down which electrons are passed to oxygen
during cellular respiration

● Cytochrome c is found in the mitochondria of

every aerobic eukaryote — animal, plant, and
protist.

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DNA: Cytochrome C

● The amino acid sequences of many of these

have been determined, and comparing them
shows that they are related.

● Human cytochrome c contains 104 amino acids,

and 37 of these have been found at equivalent
positions in every cytochrome c that has been
sequenced.

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Multiple Choice

Where is Cytochrome C found?

• Mitochondria

• Nucleus

• Golgi Apparatus

• All Life

●Gel electrophoresis:

○ mixture of DNA fragments (cut by

restriction enzymes) are put at one end
of a gel

○ electric current is applied to gel
○ DNA molecules move & are separated

by size (long to short)

● Creates a DNA fingerprint (restriction

map) that can be used to compare DNA
samples from different individuals

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DNA: Gel Electrophoresis

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Gel Electrophoresis

DNA:

DNA Fingerprint

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