Everything must evolve… - PowerPoint Presentation

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Everything must evolve…Slide3
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Charles DarwinFather of EvolutionProposed a way

how

evolution works

How

did creatures change over time?

by

natural selection

Collected a lot of

evidence to support

his ideas 1809-1882British naturalistSlide6

Voyage of the HMS Beagle

Invited to travel around the worldSlide7

Voyage of the HMS BeagleStopped in Galapagos Islands

500 miles off coast of EcuadorSlide8

Many of Darwin’s

observations

made him wonder… Why?

Darwin asked:

Why were these creatures found only on the Galapagos Islands?

Darwin found… many unique speciesSlide9

present day Armadillos

Darwin found:

Evidence that creatures have changed over time

ancient Armadillo

Darwin asked:

Why should extinct armadillos & modern armadillos be found on same continent?

Darwin found… clues in the fossilsSlide10

Darwin found:

Different shells on tortoises on different islands

Darwin asked:

Is there a relationship between the environment & what an animal

looks like?Slide11

The finches clinched it for DarwinSlide12

Darwin called this…

or

E

volution

(change in population over time)

Darwin concluded:

Each species has

descended

, with changes, from other

species

over time.

Descent

w

ith

m

odificationsSlide13

Data supports Evolutionary TheorySlide14

Most Scientific Theories have 2 componentsA statement that summarizes a series of observationsA process that produces the pattern or set of observationsSlide15

Species have changed through

time

and are related by descent from a

common

ancestor

The primary mechanism of Evolutionary Change is

Natural Selection

Darwin’s Theory of Evolution by Natural SelectionSlide16

Fossil

Record

- the

history of life

recorded

by remains from the

past

. Most fossils are at least 10,000 years old.

Body Fossils

Trace Fossils Slide17

What is found?

1. Fossil Sequence?

2. Fossil Intermediates?

- Fossils exist and fossil forms are unlike species living today

Transitional fossils have been found between:

Amphibians & reptiles, reptiles & birds,

reptiles & mammals, apes and humans

When fossils are arranged according to

their age, they show successive

evolutionary

changeSlide18

The Evolution of Horses

A particularly well-documented case of evolution within a groupSlide19

The Fossil Record is Incomplete

At the time of Darwin, the fossil record was VERY scanty. A great deal of progress has been made since, but it is far from finished.

The fossil record is relatively incomplete for several reasons:

1. Soft tissues are rarely preserved

2. Movement of the earth's crust has obliterated and/or covered many fossils

3. Fossilization takes place only in certain types of habitats and favorable environments

4. Paleontologists have not dug up every place on earth Slide20

Even if there were no fossil record, the evidence from living organisms would be more than sufficient to demonstrate the historical reality of evolutionSlide21

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Vestigial structures

Vestigial Structures

Features that have

no apparent function

Typically have an

important

function in related

species

Ex: Hindlimb joints in whales and snakesSlide22

Vestigial Structures in Humans

Appendix

Wisdom Teeth

TailboneSlide23

Evidence for the relatedness of life forms?Hypothesis: all living organisms have descended from a common ancestor

Prediction: we should also be able to see evidence of relatedness of species

-Homology

-Geographic distributionSlide24

Homology

Homology: a

similarity

between species that is the result from the inheritance of traits from a

common ancestor

The features of every creature reflect history as well as adaptation

3 types of homologies

- structural

- developmental

- geneticSlide25

Analogous Structures

Different structures,

same function

Suggests that organisms

do not

share a

close

common ancestor

Ex. Hawk, butterfly, & bat can all fly but have different wing structureSlide26

Homologous StructuresSame structure in different animals

Suggests that organisms share

common ancestor

Ex. Forelimbs of human, cat, whale, & bat

Same bone structuresSlide27

Homology vs. Analogy

Natural selection appears to have favored similar adaptations

in unrelated organisms in similar environments-->

these structures are

analogous

Whereas homologous structures

share structural similarity, but not function, analogous structures share function but not structural similarity since they evolved independentlySlide28

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display

Embryos show evolutionary history

Homologous structures in adults develop from homologous groups

of cells in embryos --> they share developmental pathwaysSlide29

Comparative EmbryologyAnalyzing embryos

with similar structures to show

common ancestorSlide30

Dog Fetus

Human fetusSlide31

Bat FetusSlide32

Genetic Homologies

All living organisms share the same

genetic code

Chromosome and

gene

similarities between

species match

evolutionary similarities

This is true for both coding regions and

“junk DNA”Slide33

Molecules reflect evolutionary divergenceSlide34

Geographic Distributions

Species that are extremely

similar

to one another tend to be

clustered

geographically (Ex.: Darwin’s finches)

Darwin used this observation to predict that fossils

of ancient humans should be found in Africa

Living species are more similar to fossil species in the same area

than they are to living species in other areas

The law of succession

general correspondence between fossil and living forms in same geographical areaSlide35

That Evolution Has Occurred Is A FactSlide36

Fossil Record - Evidence of EvolutionSlide37

How to estimate how old:1) the deeper the layer that the fossil is found in, the older it is2) the fossils

near

the surface are

younger

and more

complex

Which rock layer is the oldest?

Which fossil is older: a fossil in layer 4 or a fossil in layer 2?

What observations did you make about the organisms in layers 1-3 and 4-5? What does this tell you about the type of environment?

5

4

3

2

1Slide38

Although scientists have a found a lot of fossils (and still continue to find them!), they still have missing pieces in the fossil records of species. The camel however, has a nearly complete fossil record of it’s evolution

How is this evidence for evolution?Slide39

Change by Chance Activity Procedures: 1. You will need a pencil for this activity. You will be working with a group of students and drawing a picture. You cannot look at anyone else’s drawing.2. The drawing should be face down until the signal to begin is given.

3. I will signal the beginning and end of each 15-second interval.

4. I will give the first student in each line 15 seconds to draw, not trace, the image on the colored paper onto their blank paper.

5. The first student will then pass their drawing to the next person. The second student in each row 15 seconds to draw, not trace, the first student’s drawing on his or her own paper.

At the end of the 15 seconds, the second students pass their drawings to the third students, and so on until all students in a group have had a chance to draw the reptile.

7

. Have each group label all of their drawings with a group name, mix the order, and place them together.

I will collect each group’s drawings and redistribute each set to a different group. In groups, sequence the order of the drawings and then tape them on the wall.

Choose one person from the original group confirm the accuracy of the sequencing. Slide40

Why was sequencing the drawings difficult? How was this experience similar to sequencing fossil records? How was this experience different from sequencing fossil records?Slide41

Turn to an elbow partner and answer the question below. Discuss how to determine the correct answer.Slide42

With the same elbow partner describe the changes in the fossils you see in each layer and what they tell you about that time period.Slide43

Turn to a different partner. Compare layer C to layer F in the diagram below.

W

hat evidence do these fossils provide of changes on earth?Slide44

Living

or once living things share

common ancestors

and fossils provide

evidence

for common ancestry.Slide45

Changes in fossil records…. What do they mean?Slide46

Stasis - Punctuated equilibrium is a evolutionary theory which proposes that once species appear in the fossil record they will become

stable

, showing

little net

evolutionary change.

In this picture, the color of the moths changes very little.Slide47

Gradualism - suggest that organisms evolve through a process of slow and constant change.

For

instance, an organism that shows a fossil record of gradually increased size in small steps, or an organism that shows a gradual loss of a structure

.

In the case of the moths above, they gradually change color over time. Slide48

Physical characteristics of organisms change over time and fossils provide evidence of change.Slide49

Summarizing Strategy: 3 – 2 – 1

Describe three ways in which scientists support the theory of evolution

.

Identify two ways in which scientists know the physical characteristics of organisms change over time.

Describe why the fossil record is important.