Evidence of Evolution

Evidence for Evolution

1

Evolution

•  The gradual change in organisms over time

• Charles Darwin

  • Did not discover evolution - it was already beginning to be accepted when he did his work

  • First person to propose a reasonable mechanism for evolution (natural selection)

  • His ideas are still generally accepted today

Multiple Choice

The changes of species over time

• Embryonic 

• Natural selection 

• Mimicry 

• Evolution 

Evidence

Evidence

of

common

ancestry

among species

comes from

many sources.

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#1 Fossil Evidence



Fossils

o

Earth is

Millions

of

years old!

o

Fossils in

older layers

are

more primitive

than

those in the upper

layers.

o

Extinct

Fossils resemble

modern animals

.

o

This shows a

common

ancestry.

3

Multiple Choice

How do fossils provide evidence that evolution has happened on Earth?

• Fossils show how the sizes of certain animals has changed drastically over millions of years

• Fossils show that some species have gone extinct

• Fossils show how life forms present today are different than those from the past

• Different sedimentary rock layers provide evidence for how the environment has changed over time

Types of Fossils



Permineralization

occurs when minerals

carried by water are

deposited around a

hard structure



A

natural cast

forms

when flowing water

removes all of the

original tissue, leaving

an impression.

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Types of Fossils



Amber

-

preserved

fossils are

organisms that become trapped in

tree resin that hardens after the

tree is buried

.



Fossilized insects can occur in many ways

5

Types of Fossils



Impressions

are imprints left in

rock



Preserved remains

form when an

entire organism becomes encased in

material such as ice, ash, tar …

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Dating Fossils

7

Relative Dating of Fossils



Estimates the time

during which an

organism lived



It

compares the

placement

of fossils in layers of

rock



Scientists infer the

order in which species

existed

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Radiometric Dating of Fossils



Measures the

half

-

life

of the isotope

–

the time it takes for ½ of the

isotope to break down



Carbon

-

12

stable

;

Carbon

-

14

radioactive

(carbon in ALL organisms)



Example:

–

Carbon

-

14

has a half

-

life of

5730 years

;

decays into Carbon

-

12

–

Compare ratio of C

-

14 to C

-

12 to age

fossil

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Radiometric Dating of Fossils



Uses

Radioactive Isotopes

: atoms of

the same element with differing

neutrons



Example:

–

12

C and

14

C

–

12

C = 6 protons + 6 neutrons

–

14

C = 6 protons + 8 neutrons

10

Radiometric Dating of

Fossils

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Multiple Choice

When studying fossils, which layer of the rock has the oldest fossil?

• middle layer

• top layer

• bottom layer

#2 Geographical Distribution





Island species

most closely

resemble

nearest mainland species



Populations can show variation

from

one island to another

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evidence for evolution

Geography & environment gives

Multiple Choice

____________ explains how organisms distributed around the world may have similar features along geographic gradients of latitude, elevation, and habitat.

• Biogeography

• Fossil record

• Homologous structures

• DNA/Molecular sequencing

#3 Embryology



Embryo (

early developmental stage

) gives

evidence of evolution



Identical larvae, different adult body

forms



Similar embryos, related but diverse

organisms



Shows

common

ancestry

Larva

Adult barnacle

Adult crab

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#3 Embryology

14

Vertebrates

all share gill

slits and a

tail in their

early

embryo

stage;

Share a

common

ancestor

Multiple Choice

How does embryology support the Theory of Evolution?

• It shows that embryos who develop similarly share a common ancestor

• It shows that embryos who develop similarly are not related to one another

• It shows that organisms have the ability to evolve, or change, over the course of their lives

#4 Comparative Anatomy



The study of anatomy provides

evidence of evolution



Homologous

structures are

similar in structure but

different in function

.



Homologous structures

ARE

EVIDENCE

of a common

ancestor.

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Homologous Structures

ARM

LEG

Flipper

Wing

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Multiple Choice

What term describes part of organisms, that have a similar structure but a different function?

• homologous structure

• homologous chromosome

• vestigial structure

• analogous structure

Multiple Choice

Homologous structures are defined as the same structure but different function. In vertebrates the presence of homologous structures suggest?

• all vertebrates have a common ancestor

• all vertebrates developed at the same rate

• all vertebrates developed internally

#4 Comparative Anatomy



Analogous

structures are

similar

in function but differ in structure



Analogous structures

DO NOT

show common ancestry

Fly wing

Bat wing
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Multiple Choice

The images are examples of ?

• homologous structures

• vestigial structures

• analogous structures

Structural patterns are clues

to the history of a species.



Vestigial structures

are remnants of

organs or structures that had a

function in an early ancestor.



Examples

include ostrich wings, human

appendix, and wisdom teeth, whale

and snake pelvis/hind legs

18

Pythons have tiny

femurs (leg bone)

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Multiple Choice

The femur and pelvis bones in the organism are examples of trace organs/structures that are no longer useful. This is an example of...?

• genetic drift

• vestigial structures

• homologous structures

• fossils

#5 Molecular and Genetic

Evidence



AKA

Biochemical

Evidence



Two closely

-

related

organisms will have

similar DNA, RNA, and

protein (amino acid)

sequences

.



This also gives

evidence of a

common

ancestor.
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Multiple Choice

Scientists are studying a particular protein found in blood cells. Based on this, which animals are most closely related?

Dog: ARG - LYS - HIS - TYR

Rabbit: ARG - LYS - TYR - TYR

Elk: ARG - PRO - TYR - ARG

• Dog & Rabbit

• Rabbit & Elk

• Dog & Elk

Multiple Choice

If two organisms have similar traits of DNA they are probably

• share a common ancestor

• share a common environment

• share a common population

• speciation

Match

Match the following

• Analogous Structure

• Homologous Structure

• Comparative Embryology

• Biochemical Evidence

• Vestigial Structures

Same function different structure

Same structure different function

Comparing embryological development of different species

Comparing DNA and amino acid sequences of different species

Structures in the body of an organism that no longer work.

• Same function different structure

• Same structure different function

• Comparing embryological development of different species

• Comparing DNA and amino acid sequences of different species

• Structures in the body of an organism that no longer work.

Five examples of Evidence

for Evolution

1.

Fossils

2.

Geographical Distribution

3.

Embryology

4.

Comparative Anatomy

5.

Molecular and Genetic

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