Darwin’s Theory of EvolutionThe Puzzle of Life’s Diversity

Chapter 15-1

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What scientific explanation can account for the diversity of life?

ANSWER:

A collection of Scientific Facts, observations and hypotheses

EVOLUTIONARY THEORY-

WRITE A DEFINITION:

change over time; the process by which modern organisms have descended from ancient organisms

a well-supported testable concept that is supported by evidence

EVOLUTION:

THEORY:

The person who contributed themost to our understanding of evolution was Charles Darwin

In 1831, he joined the crew of the Beagle as a naturalist for a 5 year voyage around the world.

http://harrier.users.netlink.co.uk/Darwin_sm.jpg

Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006

DARWIN WONDERED?Why do Argentina and Australia have differentAnimals even though they have similargrassland?

Why are there no rabbits in Australia andno kangaroos in England?

Why have so many species disappeared?

How are these extinct species related to living species?

http://www.rc.umd.edu/praxis/mitchell/images/dinosaur1.gif

• Fossil record showed 2 types of organisms– Ones that were similar to animals and plants alive

at the time– Ones that were different to animals an plants alive

at the time

• Why had these species disappeared?

Charles Darwin spent one month observing life on the Galapagos Islands.

There, he encountered some unique animals, such as finches and tortoises.

http://www.darwinadventure.com/pictures/galapagos_giantortoise.jpghttp://mikebaird.com/ecuador/images/galapagos_off_ecuador_ng_map.jpg

Darwin's greatest influence

The Galάpagos Islands are close together but have very different climates.

• hot and dry, with little vegetation• more rainfall and were rich in vegetation

Each island hadits own uniqueAssortment of plant and animal species.

Biology by Miller and Levine; Prentice Hall Publishing©2006

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Pinta IslandIntermediate shell

Pinta

Isabela IslandDome-shaped shell

Hood IslandSaddle-backed shellHoodFloreana

Santa Fe

Santa Cruz

James

Marchena

Fernandina

Isabela

Tower

Giant Tortoises of the Galápagos Islands

Section 15-1

On the desert-like Hood Island,tortoises had long necks…

…while on the lush rainforest of Isabela Island,tortoises had short necks…

and on Pinta Island, tortoise neckswere somewhere in between

After his voyage, Darwin spent a great deal of time thinking about his findings.

Biology by Miller and Levine; Prentice Hall Publishing©2006

Darwin’s Theory of EvolutionIdeas that Shaped Darwin’s

ThinkingChapter 15-2

Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006

Ideas that shaped Darwin’s thinking:

James Hutton (1795)- the EARTH was shaped by geological forces occurring over very long periods of time, and the Earth ismillions of years old.

Ideas that shaped Darwin’s thinking:

Charles Lyell (1830)-the geological processes still occurring nowhave shaped Earth’s features over long periodsof time

http://www.biologydaily.com/biology/Sir_Charles_Lyell

Ideas that shaped Darwin’s thinking:

Theory of Pangaea

Ideas that shaped Darwin’s thinking:

Continental drift

convergent

divergent

Transform

Ideas that shaped Darwin’s thinking:

Thomas Malthus (1798)-• If the human population continued to grow

unchecked, there would be insufficient living space and food.

Ideas that shaped Darwin’s thinking:

Jean-Baptiste Lamarck (1830)-• one of first scientists to recognize

living things changed over time and that all species were descended from other species.

Lamarck's Hypothesis:1.Tendency towards perfection2.Use and disuse3.Inheritance of acquired traits

http://www.educa.rcanaria.es/fundoro/00.corsi.htm

What’s wrong with Lamarck’s hypothesis?Lamarck didn’t know aboutgenes and how traits are inherited.

If you lifted weights yourwhole young adult life, andthen you had children, wouldyour kids be more muscular?

NO! acquired traits can not be passed on to their offspring.

http://www.geocities.com/arnold_schwarzenegger_pictures/

The male fiddler crab uses itsfront claw to attract mates and fight off predators.

Through repeated use, the front claw becomes larger.

The fiddler passes on this acquired characteristic to its offspring

Individuals DO NOT evolve!!!!

Acquired traits cannot be inherited

What’s right with Lamarck’s hypothesis?

Lamarck was first to develop a scientifichypothesis about evolutionand recognize that organisms areAdapted to their environment

competitionhttp://www.wasatchcomputers.net/gallery/elk_fight.jpg

•Inherited adaption's that accumulate in a population over many generations= Evolution

•Living things must compete for food, shelter, space and mates

What does drive evolution?