*15.3 – Darwin Presents His Case

*Darwin’s Publication*After Darwin’s journeys he wrote and

published a book called On the Origin of Species*In this book he proposed his thoughts on

how evolution happened called natural selection

*Natural Variation vs Artificial

Selection

*Evolution by Natural Selection*Darwin proposed that as populations grew

that there would be a struggle for existence*A key factor in the above would be survival of

the fittest*Successful adaptions enable organisms to be

better suited for environment *Those adaptations are then passed on to next

generations*Those that are adapted best for their

environment will have more offspring and those that are not will either die or have few offspring*http://

www.youtube.com/watch?v=nS1tEnfkk6M*http://www.youtube.com/watch?v=GPbWJPsBPd

A&feature=fvsr

*Descent with Modification*Darwin proposed that over long periods of

time organisms developed different structures to adapt to different environments*As a result species today look different

from their ancestors*Common Descent*All species-living and extinct-were derived

from same ancestors

*The Fossil RecordArchaeopteryx

*Lucy

Beaver

NORTH AMERICA Muskrat

Capybara SOUTH AMERICA

Coypu

* Geographic Distribution

of Living SpeciesSection 15-3

Beaver MuskratBeaver andMuskratCoypu CapybaraCoypu andCapybara

Turtle Alligator

Bird Mammals

Typical primitive fish

*Homologous Body StructuresSection 15-3

*Vestigial Organs

*Similarities In Early

Development

*Concept Map

includes

Evidence of Evolution

Physical remains of organisms

Common ancestral species

Similar genes Similar genes

which is composed of which indicates which implies which implies

The fossil record

Geographic distribution of living species

Homologous body

structures

Similaritiesin early

development