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EVIDENCES FOR EVOLUTION

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EVIDENCES FOR EVOLUTION

WHAT IS EVOLUTION?

The change in the inheritedcharacteristics of biologicalpopulations over time.

Darwin uses treesas a metaphor forpattern of

evolution.

• Hierarchical• Growing• Expansion/die-offs• Single common

ancestor (trunk)

TREE THINKING

The most reproductively successful individuals pass their traits to the next generation.

NATURAL SELECTION

IDEA #2: NATURAL SELECTION

Evidences of Evolutio

n

EVIDENCE #1:

THE FOSSIL RECORD

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Fossil record provides snapshots of the past that can be assembled to illustrate a pattern of

evolutionary change over the last 4 billion years.

The youngest layer of fossils closely resembles organisms that are alive today.

Evidence #2 Mimicry

Viceroy Monarch

Why would some butterflies be

selected to look like butterflies

that are poisonous?

Mimicry https://www.youtube.com/watch?v=t-LTWFnGmegAn animal benefits due to its resemblance to another

organism.

EVIDENCE #3:

CHROMOSOMAL RECOMBINATION

https://www.youtube.com/watch?v=8FGYzZOZxMw

http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html

Humans and chimps are 99% similar genetically.

But humans have 23 pairs of chromosomes and chimpanzees have 24

pairs. How can our chromosome pairs be

different when we share almost all the same

genes?

#24

Chromosomal recombination: happens during meiosis. Can lead to different chromosomal mutations.

EVIDENCE #4:

EMBRYOLOGY

1 2 3 4 5What features make these embryos look so

similar? Can you identify their species? chicken, fish, human, rabbit, salamander

Implies a common origin

EVIDENCE #5:

HOMOLOGOUS STRUCTURES

The shading in these drawings indicates what significant fact about vertebrate forearms despite their extreme

differences in function and appearance?

ALL VERTEBRATE LIMBS ARE ASSEMBLED THIS WAY REGARDLESS OF THEIR USE!

These are structures shared by related organisms that were inherited from a common ancestor.

Evidence #6

Analogous Structures

ANALOGOUS STRUCTURES

• Bat wings have bones, insect wings do not

Evolved separately and not evidence of a

common ancestor

Why would this be an evidence for evolution?

When two different species live in an environment, they evolve the same way. Definitive example of how the environment causes natural selection.

EVIDENCE #6:

VESTIGIAL STRUCTURES

Vestigial Structures

Structures or attributes that have lost most or all of their ancestral function in a given species, but have been retained during the process of evolution.

Can you think of 3?

https://www.youtube.com/watch?v=rFxu7NEoKC8

Humans can have their appendix removed and still live a normal life. Where does the

appendix come from if it’s non-essential?

Stores lymphatic tissue (immune system) in different organisms.

Wisdom Teeth

Anthropologists believe wisdom teeth, or the third set of molars, were the evolutionary answer to our ancestor's early diet of coarse, rough food – like leaves, roots, nuts and meats – which required more chewing power and resulted in excessive wear of the teeth.

Baby Teeth

Vestigial structures - SciShow

Evidence #7

Atavisms

Atavisms

Atavism is the tendency to revert to ancestral type, “evolutionary throwback”.

Traits reappearing which had disappeared generations before.

Shows that the ancestral genes are still a part of our DNA, even if they are not expressed.

Evidence #8

Camouflage

How has this organism adapted to its environment? What kinds of selective pressure

could have led to this trait?

http://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.camouflage/evolution-of-camouflage/

CAMOUFLAGE

QUESTIONS?

Monkey-scopes trial

http://media.davis.k12.ut.us/SAFARI/montage/play.php?keyindex=83280&location=local&filetypei

d=12