evolution theories 2012

7/31/2019 Evolution Theories 2012

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THEORIES OFEVOLUTION


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Jean Baptiste LAMARCK1744 1829

Lamarck rejected fixity He proposed a theory

of evolution which isattractive but it waseventually rejectedbecause of the wayinheritance works

Lamarck
http://io.uwinnipeg.ca/~simmons/16cm05/1116/16evolut.htmhttp://io.uwinnipeg.ca/~simmons/16cm05/1116/16evolut.htm


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Adaptation andspecialisation Lamarck noticed that organisms adapted

to a particular niche had well developedspecialised organs

For example a carnivore will have longcanine teeth to grip its prey


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The Law of Use andDisuse He proposed that if an organ is used a lot

it will develop and strengthen If it is not used it will atrophy

He called this the law of use and disuse

2008 Paul Billiet ODWS
http://www.saburchill.com/IBbiology/bio_hp.htmlhttp://www.saburchill.com/IBbiology/bio_hp.html


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The Inheritance of AcquiredCharacteristics

if an organism developed a characteristicfeature through adapting to a new way oflife during its lifetime, it would pass this

on to its offspring The classic example given is that of the

giraffes neck:


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LAMARK


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Disproving Lamarck Characteristics acquired during the lifetime of a

parent are not passed onto the offspring An athlete who develops a large muscle mass

through training does not have children who

already possess this large muscle mass Ernst Haeckel

In an attempt to disprove Lamarckism he is saidto have cut off the tails of mice for severalgenerations. The babies born from this line oftailless mice still grew tails as long as theirancestors. This was not exactly a fair test as themice had not stopped using their tails in anattempt to adapt to their environment. They stillfound their tails useful

L t


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Lamarc sm n evo ut ontheory today

evolutionary change takes placegradually and constantly

In some cases evolution leads to

complexity

learned behaviour patterns can bechanged within a generation

Members of a social group who haveacquired the behaviour in their lifetimeswill pass these learned skills onto othersincluding their children


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2006-2007

Insect eaters

Bud eater

Seed eaters

Cactuseater

Warbler

finch

Tre

ef

inch

es

G

roundfin

ches

NaturalSelection


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Charles Darwin Proposed a way how

evolution works Howdid creatures

change over time? by natural selection

Collected a lot ofevidence to support

his ideas 1809-1882 British naturalist


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Robert FitzroyRobert Fitzroy

Voyage of the HMS Beagle Invited to travel around the world

1831-1836 (22 years old!) makes many observations of nature

main mission of the Beagle was to chart

South American coastline


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Voyage of the HMS Beagle Stopped in Galapagos Islands

500 miles off coast of Ecuador


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GalapagosRecently formed volcanicislands. Most of animalson the Galpagos livenowhere else in world,but they look like species

living on South Americanmainland.

800 km west of Ecuador


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Darwin asked:

Why were these creatures found

only on the Galapagos Islands?

species


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Wallaces Formative Years


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organisms are potentially capable of producing large numbers ofoffspring.

Different members of the same speciesare all slightly different


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organisms are potentially capable ofproducing large numbers of offspring.


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Observation 3


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Observation 3All living things vary. Different

members of the same species are all slightlydifferent


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Biston betularia

Industrial Revolution (Manchester, 1850)

White color, lives overtrunks, which arecommonly covered inlichens. Non visible forpredators: Birds.

There are mutatedindividuals with darkpigmentation

BernardKettlewell(1907-1979)

Formas melnicas:

Carbonaria (CC)

Insularia (Cc)

Forma silvestre:

Tpica (cc)


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Around 1850, during industrial revolution,atmosphere pollution reduced the presence of

lichens The trunks of trees turned dark colour

White moths turnedto be easy prey for

birdsIN 1900, Moths were 99%

dark colour.


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As time has passed, pollution hasbeen reduced

Lichens came back to the treetrunks and the situation changed

again

The whiteThe white

moth is nowmoth is nowthe mostthe most

common one,common one,

as it wasas it was

before.before.


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Suppose there is a population of rabbits.The color of the rabbits is governed by two

incompletely dominant traits: black furrepresented by B and white furrepresented by b. A rabbit with thegenotype of BB would have a phenotypeof black fur, a genotype of Bb would

have gray fur (a display of both black andwhite) and a genotype of bb would have

a phenotype of white fur.If this population of rabbits were put into an

area that had very dark black rocks aswell as very white colored stone, What

kind of selection would you predict?

M d f l ti
http://en.wikipedia.org/wiki/Genotypehttp://en.wikipedia.org/wiki/Phenotypehttp://en.wikipedia.org/wiki/Phenotypehttp://en.wikipedia.org/wiki/Genotype


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Modes of selection


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Types of evolution

1. Divergent evolution 2. Convergent evolution


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Divergent Evolution

1. Divergent evolution Two different populations of a species that

experience different selection pressuresmayas a result become genetically different from one

another Once in a very great while, the two populations will

become so different that they cannot reproduce togetheranymore (this then becomes speciation).


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Divergent Evolution

http://www.biology-online.org/images/darwin_finches.jpg


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Divergent Evolution


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Divergent Evolution


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Divergent Evolution


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2. Convergent evolution Start with two very different species; they

experience similar selection pressuresand through time come to look and/or

behave similarly.

Convergent Evolution


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Fish Reptile MammalWhat is the

similar

selection

pressure?


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What is thesimilar

selection

pressure?

http://www.votawphotography.com

/photo/Animals/animals.htm

http://www.hundekosmos.de/images/greyhound_517.jpg

Speed to catch prey

(cheetah) andspeed to win racesand be bred.


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MarsupialMammalsPlacentalMammals

THE PUNCTUATED


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THE PUNCTUATEDEQUILIBRIUM MODEL They observed that the

fossil record gives adifferent picture for theevolution

They claim that there werelong periods ofstasis (4-10 million years) involvinglittle evolutionary change

Then occasional rapidformation of new

species As little as 5,000 - 50,000

years

Stephen JGould

Niles Eldredge

2008 Paul Billiet ODWS
http://peer.tamu.edu/curriculum_modules/Ecosystems/Module_2/storytime.htmhttp://peer.tamu.edu/curriculum_modules/Ecosystems/Module_2/storytime.htmhttp://www.seedmagazine.com/news/2006/07/andrea_barrett_niles_eldredge.php?page=all&p=yhttp://www.saburchill.com/IBbiology/bio_hp.htmlhttp://www.saburchill.com/IBbiology/bio_hp.htmlhttp://www.seedmagazine.com/news/2006/07/andrea_barrett_niles_eldredge.php?page=all&p=yhttp://peer.tamu.edu/curriculum_modules/Ecosystems/Module_2/storytime.htmhttp://peer.tamu.edu/curriculum_modules/Ecosystems/Module_2/storytime.htm


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Graph of Gradual Evolution

http://anthro.palomar.edu/synthetic/images/graph_of_p
http://anthro.palomar.edu/synthetic/images/graph_of_phyletic_gradualism.gifhttp://anthro.palomar.edu/synthetic/images/graph_of_phyletic_gradualism.gif


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Homework

State what mechanisms of evolution doyou know and describe it in one paragraph

evolution theories 2012

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