Evidence for Evolution 20Properties%20of%20Life.htm.

Evidence for EvolutionEvidence for Evolution

http://humans4.beyondgenes.com/

http://faculty.southwest.tn.edu/rburkett/GB%20Properties%20of%20Life.htm

Snowmelt from the Snowmelt from the mountains washes sediments mountains washes sediments into lakes and shallow seas.into lakes and shallow seas.

FossilizatioFossilizationn

Overtime, these sediments Overtime, these sediments pile up and compress the pile up and compress the older sediments below into older sediments below into rock.rock.


These layers are called rock These layers are called rock strata.strata.


A few organisms that die in A few organisms that die in the sediment become the sediment become fossilized.fossilized.


Fossils are the preserved Fossils are the preserved remains or markings left by remains or markings left by organisms that lived in the organisms that lived in the past.past.


Depending on the process, it could Depending on the process, it could take anywhere from tens of take anywhere from tens of thousands to millions of years for thousands to millions of years for fossils to form.fossils to form.


Thus the oldest Thus the oldest layer and any layer and any fossils it fossils it contains is at contains is at the bottom;the bottom;

and the and the youngest layer youngest layer and fossils are and fossils are at the top.at the top.

YoungesYoungestt

OldestOldest

The Fossil The Fossil RecordRecord

YoungesYoungestt

OldestOldest

The fossil record shows that The fossil record shows that life became more complex life became more complex over time.over time.

SimpleSimple ComplexComplex


The positions of the fossils in the The positions of the fossils in the rock strata can reveal their rock strata can reveal their relative age.relative age.

OldestOldest

YoungesYoungestt


The fossil record is this The fossil record is this chronological collection of life’s chronological collection of life’s remains in rock layers, recorded remains in rock layers, recorded during the passage of time.during the passage of time.

OldestOldest

YoungesYoungestt


When land masses collide, mountains may When land masses collide, mountains may form.form.

The energy from these collisions can The energy from these collisions can bend and fold rock.bend and fold rock.

Why are marine fossils found on mountain Why are marine fossils found on mountain tops?tops?

Mountain building Mountain building can force marine can force marine fossils from the sea fossils from the sea floor high up onto floor high up onto mountain peaks.mountain peaks.

Burgess Shale, B.C., Burgess Shale, B.C., CanadaCanada

Anomalocaris canadensisAnomalocaris canadensis

If the folding is severe enough, the If the folding is severe enough, the fossil record may appear to be fossil record may appear to be upside down.upside down.

Oldest

Younge

st

The fossil record provides evidence of The fossil record provides evidence of Earth’s changing life.Earth’s changing life.

The oldest evidence of life consists of The oldest evidence of life consists of chemical traces in rocks from chemical traces in rocks from Greenland that are 3.8 billion years old.Greenland that are 3.8 billion years old.

Rocks of Greenland’s Akila island.

http://www.sciencedaily.com/releases/2006/07/060721090947.htm



Fossils of prokaryotes (bacteria Fossils of prokaryotes (bacteria and archaea) have been found and archaea) have been found in rocks about 3.5 billion years in rocks about 3.5 billion years in age.in age.

CyanobacteriaCyanobacteria

The fossil record provides evidence of The fossil record provides evidence of Earth’s changing life.Earth’s changing life.

Fossils of prokaryotes Fossils of prokaryotes (bacteria and archaea) (bacteria and archaea) have been found in rocks have been found in rocks about 3.5 billion years in about 3.5 billion years in age.age.

Stromatolites“Bacteria poop”

These data fit with the molecular and cellular These data fit with the molecular and cellular evidence that prokaryotes are the oldest form evidence that prokaryotes are the oldest form

of life. of life.

Photosynthetic Photosynthetic

bacteriabacteria

Fossils in younger layers of rock record the Fossils in younger layers of rock record the evolution of various groups of eukaryotic evolution of various groups of eukaryotic

organismsorganisms

Fossils of species that become Fossils of species that become extinctextinct——species that no longer exist—help scientists species that no longer exist—help scientists

reconstruct the past.reconstruct the past.

Paleontologists (scientists who study fossils) Paleontologists (scientists who study fossils) have discovered fossils of many ancestral life have discovered fossils of many ancestral life

forms that link past and present.forms that link past and present.

http://www.bio.miami.edu/dana/106/106F05_4.html

For example, fossil evidence supports the For example, fossil evidence supports the hypothesis that whales, which have no hind hypothesis that whales, which have no hind limbs, evolved from land-dwelling ancestors limbs, evolved from land-dwelling ancestors

that had four limbs.that had four limbs.

Paleontologists digging in Egypt and Pakistan Paleontologists digging in Egypt and Pakistan have identified ancient whales that had hind have identified ancient whales that had hind

limb bones.limb bones.

Basilosaurus, which lived about 40 million Basilosaurus, which lived about 40 million years ago is one of these early whales.years ago is one of these early whales.

Even larger leg bones are found in fossils of Even larger leg bones are found in fossils of older whale species that may have split their older whale species that may have split their

time between living on land and in water.time between living on land and in water.

Ambulocetus Ambulocetus natansnatans

These These examples of examples of transitional transitional fossils show fossils show the evolution the evolution of the whale of the whale over millions over millions

of years.of years.

In the early 1900’s, whalers documented many In the early 1900’s, whalers documented many cases of reduced hind-limbs in humpback and cases of reduced hind-limbs in humpback and

sperm whales.sperm whales.

FemurFemur

metatarsmetatarsalal

tibia tibia

PelvisPelvis

tarsutarsuss

The study of embryo development has also The study of embryo development has also provided evidence supporting evolution.provided evidence supporting evolution.

For example, these For example, these fetal structures in fetal structures in whales that disappear whales that disappear before birth:before birth: Hind limb budHind limb bud Body HairBody Hair Rudimentary ear Rudimentary ear

pinnae*pinnae* Brain olfactory lobes Brain olfactory lobes Teeth on baleen Teeth on baleen

whales.whales.*Outer ear (Carried as rare atavisms in all whales, rudimentary in *Outer ear (Carried as rare atavisms in all whales, rudimentary in belugas)belugas)

Beluga Whale Embryo

Expected Expected ≠ Observed≠ Observed

When Darwin set sail on the Beagle, he When Darwin set sail on the Beagle, he believed a recent world-wide flood believed a recent world-wide flood killed all but a handful of each species. killed all but a handful of each species.

Based on his Based on his readings and readings and

discoveries during discoveries during his 5-year voyage, his 5-year voyage, however, Darwin however, Darwin began to question began to question

this account. this account.

Sediment SortingSediment Sorting

He wondered why the composition of thousands He wondered why the composition of thousands of feet of rock layers he observed did not of feet of rock layers he observed did not conform to what one would expect from a conform to what one would expect from a

world-wide flood.world-wide flood.Expected Expected (flood)(flood)

ObserveObservedd

ConglomeraConglomeratete

SlateSlate

SandstonSandstonee

DisconformiDisconformityty

ShalShalee

ShalShalee

Fossil OganizationFossil Oganization

Darwin was also puzzled as to why fossils were Darwin was also puzzled as to why fossils were sorted out by complexity, rather than laid down sorted out by complexity, rather than laid down indiscriminately as would be expected if a world-indiscriminately as would be expected if a world-

wide flood occurred.wide flood occurred.YoungesYoungestt

Expected Expected (flood)(flood)

ObserveObservedd

OldestOldest

Geographic DistributionGeographic Distribution

Darwin also wondered why there was an Darwin also wondered why there was an uneven distribution of species around the uneven distribution of species around the

world. world.


For example, Australia is home to so many For example, Australia is home to so many kinds of pouched animals (marsupials)—such as kinds of pouched animals (marsupials)—such as koalas, kangaroos, and wombats—while very koalas, kangaroos, and wombats—while very

few placental animals—such as deer and few placental animals—such as deer and squirrels—live there.squirrels—live there.

KoalaKoala KangaroKangarooo

WombatWombat


Darwin discovered that the koala’s diet is Darwin discovered that the koala’s diet is restricted to a few subspecies of restricted to a few subspecies of

eucalyptus.eucalyptus.Eucalyptus is a poor Eucalyptus is a poor nutrient food, which nutrient food, which

accounts for the accounts for the koala’s arboreal koala’s arboreal

lifestyle, low lifestyle, low metabolic rate, and metabolic rate, and

low energy low energy requirements.requirements.


According to the world-According to the world-wide flood account at the wide flood account at the time, only a few koala’s time, only a few koala’s survived the flood and survived the flood and

were deposited on top of were deposited on top of Mt. Ararat in Turkey about Mt. Ararat in Turkey about

4,500 years ago. 4,500 years ago.

Mt. Mt. AraratArarat


Darwin wondered how so few koalas could travel Darwin wondered how so few koalas could travel over 9,000 miles from Mt. Ararat to Australia, over 9,000 miles from Mt. Ararat to Australia,

eating a conventional trail of long-disappeared eating a conventional trail of long-disappeared eucalyptus, without leaving a trail of koala eucalyptus, without leaving a trail of koala

fossils behind.fossils behind.

Homologous StructuresHomologous Structures

Darwin also pointed to certain similarities in Darwin also pointed to certain similarities in structure among species as clues to their structure among species as clues to their

evolutionary history.evolutionary history.For example, the forelimbs of all mammals For example, the forelimbs of all mammals consists of the same skeletal parts, even consists of the same skeletal parts, even

though the functions of these forelimbs differ.though the functions of these forelimbs differ.


Such similar structures in species sharing a Such similar structures in species sharing a common ancestor are called common ancestor are called homologous homologous

structuresstructures..


Darwin described evolution as a remodeling Darwin described evolution as a remodeling process.process.

Structures that originally functioned one way in Structures that originally functioned one way in ancestral species become modified as they take ancestral species become modified as they take

on new functions.on new functions.


This idea is what Darwin meant by “descent This idea is what Darwin meant by “descent with modification.”with modification.”

Less than a perfect designLess than a perfect design

Darwin noted limitations of this retrofitting are Darwin noted limitations of this retrofitting are evident in structures that are less than evident in structures that are less than

perfect.perfect. For Example:For Example:Why is the giant Why is the giant panda's 'thumb' panda's 'thumb' made of an altered made of an altered wristbone (the radial wristbone (the radial sesamoid), rather sesamoid), rather than the normal than the normal digit?digit?

Sub-optimal designSub-optimal design

Why are vertebrate eyes wired “backwards,” thus Why are vertebrate eyes wired “backwards,” thus creating a blind spot and increasing susceptibility for creating a blind spot and increasing susceptibility for

detached retinas? detached retinas?

Sub-optimal designSub-optimal design

Why don’t tarsiers have a reflective membrane (tapetum Why don’t tarsiers have a reflective membrane (tapetum lucidum) in the back of their eyes like cats do for seeing lucidum) in the back of their eyes like cats do for seeing

in the dark?in the dark?

No tapetum No tapetum membrane membrane results in results in oversized oversized

eyes.eyes.

Presence of Presence of the tapetum the tapetum

allows eyes to allows eyes to be much be much smaller.smaller.

Knee and Back ProblemsKnee and Back ProblemsWhy do humans have knee and back problems? Is it Why do humans have knee and back problems? Is it

because the human spine and knee joints were because the human spine and knee joints were derived from ancestral structures that supported derived from ancestral structures that supported four-legged mammals—not two legged mammals four-legged mammals—not two legged mammals

that walked upright.that walked upright.

http://photobucket.com/

Speaking of walking upright, a single Speaking of walking upright, a single mutation in a gene related to balance mutation in a gene related to balance prevents these individuals from walking prevents these individuals from walking on two legs. To get around, they must on two legs. To get around, they must walk on all fours.walk on all fours.

Vestigial StructuresVestigial Structures

Darwin also pointed to vestigial structures, which are Darwin also pointed to vestigial structures, which are homologous structures that survive as degenerate, homologous structures that survive as degenerate,

imperfect versions of what they should be.imperfect versions of what they should be.

Nictitating Nictitating membranemembrane

Wings for Wings for flightflight

Calabar Calabar poto (a poto (a

primate)primate)

FunctioninFunctioningg

Human (primate)

EagleKiwi bird

NonfunctioninNonfunctioningg

FunctioninFunctioninggNonfunctioninNonfunctioningg


Often, vestigial structures are reduced in size.Often, vestigial structures are reduced in size.

Canine Canine teethteeth

AppendiAppendixx(Digestio(Digestio

n of n of plant plant

material)material)


Some skinks have one Some skinks have one or two pairs of legs or two pairs of legs

that are not used for that are not used for walking.walking.

Kasner’s Skink

Cape Skink

There are many birds with There are many birds with wings that can’t use them wings that can’t use them

for their original function—to for their original function—to fly.fly.

Kakapo Kakapo parrotparrot

Penguin

Ostrich

Cassowary

Vestigial StructuresVestigial StructuresCan you figure out what the vestigial structure is?Can you figure out what the vestigial structure is?

Cave Cave salamandsalamand

erer

Dandelion

Weevle (apertocyclus)

Fused wing covers Fused wing covers permanently permanently enclose fully enclose fully

developed wings.developed wings.

The dandelion has a The dandelion has a flower that is not flower that is not needed, since it needed, since it

reproduces asexually.reproduces asexually.

The eyes, which The eyes, which contain retinas and contain retinas and lenses, are covered lenses, are covered with a nonfunctional with a nonfunctional

eyelid.eyelid.

Dandelions even Dandelions even produce pollen, produce pollen, which are not which are not

needed in asexual needed in asexual reproduction.reproduction.

Atavistic StructuresAtavistic Structures

Ancient Ancient horse horse

(miohippus(miohippus) 25 -32 ) 25 -32

myamya

Modern Modern horsehorse

Atavisms are traits of distant ancestors that Atavisms are traits of distant ancestors that reappear in the modern day. In order for the trait reappear in the modern day. In order for the trait to be an atavism, an organism's parents can't to be an atavism, an organism's parents can't have the trait, and neither can recent ancestors.have the trait, and neither can recent ancestors.


There are many fossils of snakes showing leg There are many fossils of snakes showing leg structures.structures.

100 million year 100 million year old snake fossil old snake fossil Pachyrhachis Pachyrhachis

problematicusproblematicus

Hind legs on snakes should not to be confused with snake Hind legs on snakes should not to be confused with snake penisespenises

Occasionally Occasionally modern snakes modern snakes are found with are found with one or two hind one or two hind

legs bearing legs bearing claws.claws.

And in 2006, Japanese fishermen caught a And in 2006, Japanese fishermen caught a bottlenose dolphin that had atavistic hind bottlenose dolphin that had atavistic hind

limbs.limbs.Embryo of a Embryo of a

spotted spotted dolphin at 24 dolphin at 24

daysdays

Hind limb budHind limb bud


Atavistic structures in Atavistic structures in humanshumans

In rare cases humans In rare cases humans are born with tails. are born with tails.

Occasionally a person Occasionally a person has a tail that can be has a tail that can be wiggled.wiggled.

Atavistic structures in Atavistic structures in humanshumans

Human Human EmbryoEmbryo

Human tail Human tail vertebraevertebrae

TailTail

In the embryo In the embryo stage, all humans stage, all humans start out with a tail. start out with a tail. As the embryo As the embryo grows, the tail grows, the tail disappears.disappears.

Normal human Normal human coccyx (tail coccyx (tail

bone)bone)

Some tails have additional Some tails have additional vertebrae with attached vertebrae with attached muscles and nerves. This is muscles and nerves. This is why some people can wiggle why some people can wiggle their tails.their tails.

Atavistic StructuresAtavistic Structures1 person in 25 usually has an extra nipple that runs 1 person in 25 usually has an extra nipple that runs down the embryonic milk line. In most cases the down the embryonic milk line. In most cases the extra nipples look like blemishes or moles, but in extra nipples look like blemishes or moles, but in some cases can be well developed and actually some cases can be well developed and actually lactate (produce milk). lactate (produce milk).

Supernumerary Celebrities: Supernumerary Celebrities: Mark Wahlberg, Joanna Mark Wahlberg, Joanna Krupa, Lilly Allen, Harry Krupa, Lilly Allen, Harry Styles (2), Tilda Swinton, Styles (2), Tilda Swinton, Carrie Underwood, Carrie Underwood,

In humans, In humans, as many as as many as eight nipples eight nipples can appear can appear along the along the milk line as milk line as shown shown above. above.

Both males Both males and females and females can be born can be born with this with this condition. If a condition. If a male baby is male baby is born with too born with too much much estrogen, it estrogen, it will produce will produce milk from its milk from its nipples.nipples.

Is hypertrichosis an atavistic Is hypertrichosis an atavistic structure?structure?

Jesus 'Chuy' Aceves Jesus 'Chuy' Aceves (isolated to X (isolated to X chromosome)chromosome)

Lilia Lilia AcevesAceves Larry GomezLarry Gomez Julia Julia

PastranaPastrana

Fedor JefticheffFedor Jefticheff““JoJo”JoJo”

Fedor JefticheffFedor Jefticheff““Lionel”Lionel”

Answer: Answer: UnknownUnknown

Phylogenetic Phylogenetic relationshipsrelationships

Among siblings, Among siblings, the DNA and the DNA and protein sequences protein sequences are very similar.are very similar.

However, the However, the sequences of unrelated sequences of unrelated individuals of the same individuals of the same species show more species show more differences.differences.

This idea of This idea of molecular molecular comparison extends comparison extends to studying to studying relationships relationships between species.between species.If two species have If two species have genes and proteins genes and proteins with sequences that with sequences that match closely, match closely, biologists conclude biologists conclude that the sequences that the sequences must have been must have been inherited from a inherited from a relatively recent relatively recent common ancestor. common ancestor.

Dalmation Dingo

Grey Wolf

1 mya


Recent commo

n ancesto

r

In contrast, the greater In contrast, the greater number of differences number of differences in DNA and protein in DNA and protein sequences between sequences between species…species…

Dalmation Dingo

Grey Wolf

Cat

Hesperocyon

45 mya

1 mya

the less likely they the less likely they share as close a share as close a common ancestor.common ancestor.


Distant common ancestor

Recent commo

n ancesto

r

Over time, the Over time, the number of number of chromosomes may chromosomes may change as new change as new species emerge.species emerge.

Chromosome Count

dogs, dingos, dogs, dingos, coyotes and wolves coyotes and wolves have 78 have 78 chromosomes.chromosomes.

For example: house For example: house cats, tigers and lions cats, tigers and lions have 38 have 38 chromosomes;chromosomes;

http://en.wikipedia.org/wiki/List_of_number_of_chromosomes_of_various_organisms

ChromosomesChromosomes

This is just one of This is just one of the many reasons the many reasons why dogs can’t mate why dogs can’t mate with cats.with cats.

78

38

http://en.wikipedia.org/wiki/List_of_number_of_chromosomes_of_various_organism

The hemoglobin molecule The hemoglobin molecule provides an excellent provides an excellent example of biochemical example of biochemical evidence for evolutionary evidence for evolutionary relationships.relationships.

Hemoglobin is the protein Hemoglobin is the protein that carries oxygen in the that carries oxygen in the blood.blood.

The human The human hemoglobin protein hemoglobin protein consists of 287 amino consists of 287 amino acids.acids.

HemoglobiHemoglobinn

Red blood Red blood cellscells

4 amino acids4 amino acids

Molecular Molecular biologybiology

Molecular Molecular biologybiologyAssume a common Assume a common

ancestor has the following ancestor has the following hemoglobin amino acid hemoglobin amino acid sequence: sequence:

Val-His-Thr-Pro-Glu-Lys-Val-His-Thr-Pro-Glu-Lys-SerSer

One million generations later, One million generations later, some of its descendents some of its descendents inherit a version with a inherit a version with a mutation (yellow).mutation (yellow).

Val-His-Val-His-GlyGly-Pro-Glu-Lys--Pro-Glu-Lys-SerSer

As the years pass by, more As the years pass by, more and more mutations appear in and more mutations appear in the heritable sequences.the heritable sequences.

Val-His-Val-His-GlyGly-Pro-Glu--Pro-Glu-ArgArg--SerSer

Thus, the longer the sequence is Thus, the longer the sequence is passed down to descendents, passed down to descendents, the greater the number of the greater the number of mutations that will accumulate.mutations that will accumulate.

CysCys-His--His-PhePhe-Pro-Glu--Pro-Glu-ArgArg--SerSer

Note that this amino Note that this amino acid position mutated acid position mutated twice.twice.

Molecular Molecular biologybiologyNot all DNA accumulates mutations at the same Not all DNA accumulates mutations at the same rate.rate.

A T C C T T T G A C A T C C T T T G A C TT

For example, if the section For example, if the section of DNA is important to of DNA is important to protein synthesis, then we protein synthesis, then we can expect very few can expect very few mutations to occur over mutations to occur over time.time.

A T C C T A T C C T AA T G A C T G A C TT

If the section of DNA is not If the section of DNA is not involved in protein coding, involved in protein coding, then we can expect a then we can expect a greater number of greater number of mutations over the same mutations over the same period of time.period of time.

10 million years

10 million years

1 1 mutationmutation

3 3 mutationsmutations

A T C C T T T G A C A T C C T T T G A C TT

A T A T TT C T C T AA T G A C T G A C CC

Molecular Molecular biologybiologyThis graph shows how many of the 287 amino acids in This graph shows how many of the 287 amino acids in

human hemo-globin differ when compared to the human hemo-globin differ when compared to the hemoglobin of other organisms.hemoglobin of other organisms.

The average mutation rate for a given gene in all creatures is about 1 x 10-6 mutations per gene per generation (or one mutation / gene / million generations on average).

As you can see, the gorilla’s hemoglobin sequence As you can see, the gorilla’s hemoglobin sequence when compared to humans, differs in only one amino when compared to humans, differs in only one amino acid, inferring a close relationship.acid, inferring a close relationship.

The mutation rate for humans is estimated to be about 2.2 x 10-9 mutations per base pair per year. With about 6.3 billion base pairs per genome, that works out to around 14 transmissible mutations per year per person.


On the other hand, there are 125 differences On the other hand, there are 125 differences when compared to the lamprey, indicating a when compared to the lamprey, indicating a very distant relationship. very distant relationship.


http://geology.fullerton.edu/whenderson/Fal201L2005/DogEvolution/Dog%20Website/EVOLUTION.HTML

Phylogenetic trees like the one shown below are Phylogenetic trees like the one shown below are developed by combining morphological, geographical developed by combining morphological, geographical and molecular data.and molecular data.

http://geology.fullerton.edu/whenderson/Fal201L2005/DogEvolution/Dog%20Website/EVOLUTION.HTML

The EndsThe Ends

Date post:	28-Jan-2016
Category:	Documents
Upload:	darlene-holland
View:	219 times
Download:	0 times

Evidence for Evolution 20Properties%20of%20Life.htm.

Documents