Darwin vs. Lamarck

Jean-Baptiste LaMarck

French, Early 1800’s

Theory of

Inheritance of

Acquired Characteristics Two main points…

1. Principle of Use & Disuse: • Most used body structures develop, unused

structures waste away

2. Inheritance of Acquired Characteristics:

Once the structure is modified, the new trait can be inherited (passed to offspring)

Explain the picture below as if you were LaMarck…

Why we don’t believe him…

Genetics: Gregor Mendel discovered that

traits are passed down through GENES (which aren’t affected by the outside world in that way)

Experiments: show that changes that occur in an animal’s life are not passed on to its offspring

Charles DarwinCharles Darwin“The Father of Evolution”“The Father of Evolution”

1831- sailed on the HMS Beagle to the Galapagos Islands.

Studied many species of finches.Published book in 1845:

– “On the Origin of Species by Natural Selection”

Darwin’s Theory of Evolution(don’t copy all this it’s on your handout)

“Survival of the Fittest”

“Natural Selection”

Four main points…

1. More organisms are produced than can survive…leads to COMPETITION OVER RESOURCES

Ex’s of resources…– Water– Food– Habitat– Mates

2. Individuals within a population vary, and some of these traits are heritable.

3. Some variations are FAVORABLE (increase chances for survival/ reproduction)

Male vs. Female Cardinals

Male color attracts female= reproductive advantage

4. Better adapted individuals survive and reproduce

These are the individuals that will pass on their genes to the next generation.

This can change the GENE POOL:– Includes all the genes of every reproductive

member of a population

What The theory of evolution IS NOT!!!

It does NOT occur in INDIVIDUALS…only populations!

It does NOT happen quickly…the Earth has a Looooooong history!

It does NOT explain how life came to be on Earth, just how it evolved after it was here.

It does NOT have any driving force except the competition for limited resources.

Darwin’s Finches…p 558

Illustrate SPECIATION: when a species breaks into two (or more)– The organisms in the two species can no longer…

INTERBREED

What could cause this to happen?– Geographic barriers– Occupy a new niche/habitat– Reproductive Isolation-

What would Darwin say to explain why giraffe’s have such long necks?

See pg. 553

Evolution- “Change Over Time” All of the changes that have occurred in living things since the

beginning of life on Earth

History of the Earth

700 million years ago…

Evolution occurs over MANY generations Evolution occurs within POPULATIONS

(NOT individuals) Evolution involves genetic changes in a

SPECIES– (Members of a species interbreed to produce

healthy, fertile offspring)

Evidence for Evolution

FOSSIL EVIDENCE-Provides TRANSITIONAL LINKS

Archaeopteryx- links reptiles and birds

Anatomical EvidenceHOMOLOGOUS STRUCTURES

structures that are similar because they were inherited from a

COMMON ANCESTOR

ANALOGOUS STRUCTURES

similar in function, but NOT inherited from a common

ancestor

NOTE: similar structure, but NOT always function!

NOTE: similar FUNCTION, but not STRUCTURE

More Anatomical Evidence:Vestigial Structures

Vestigial Structures are undeveloped structures that were functional in some ancestor, but are no longer needed in that organism.

EMBRYOLOGY- suggests common ancestors

BIOGEOGRAPHICAL EVIDENCE When we study the distribution of plants and animals on the planet,

we notice:– Animals evolved differently in each of the biogeographical regions– We see evidence that as the continents drifted, organisms were

separated and evolved.

BIOCHEMICAL EVIDENCE

Almost all living things use the same biochemical molecules– DNA, Protein, ATP

Vast diversity came about by only slight differences in the same genes– The more closely “related” the organisms are, the

more similar their DNA

Other Evidence…

1. Mimicry and Camoflauge

2. Antibiotic Resistance