Animals of the Galapagos Domed tortoises were found

Animals of the Galapagos

Domed tortoises were found in wet areas rich in mosses and short plants. Saddle-back tortoises were found in areas with lots of tall plants.

Darwin’s Famous Finches

What did he see in the finch? • Darwin found that finches with strong, thick beaks lived in areas with a lot of large, hard-shelled nuts. • Finches with more delicate beaks were found where insects or fruits were available.

• These observations made Darwin realize that each was adapted to a different “niche” for where they lived. • These observations helped Darwin establish his theory about ‘Natural Selection’.

Origin of Species: By Means of Natural Selection • Published 1859 • Sold every copy on first day • Did not talk about human evolution • Avoided term evolution

Artificial Selection • Artificial Selection: – In artificial selection, nature provided the variation, and humans selected those variations that they found useful • Dog and pigeon breeding helped guide Darwin’s thinking about natural selection

Natural Selection • Natural Selection (survival of the fittest) – Process by which individuals that are better suited (adapted) to their environment, survive and reproduce most successfully. * The environment determines if a trait is passed on or not! Bummer of a birthmark!

The Mechanism - Natural Selection • More offspring are born than can survive (overproduction) • Organisms in a population will show differences due to genetic inheritance or mutation. (Variation) • Those offspring that have the best adaptation for the EXISTING environment will survive to produce the most offspring (Adaptation) • The environmentally selected adaptations (traits) will be passed on to future generations (Descent with modification)

3. The brown beetles will have a lot of b brown beetle babies (i. e. the favorable Trait!) Overproduction, Adaptation 1. There is variation 2. Green and brown 3. beetles 2. The green beetles are getting eaten more, they will reproduce less. End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. Descent with modification

Where do new traits come from? • Mutations of genes!!! • How? – Recombination of genes through sexual reproduction.

What’s need got to do with it?

Remember Lamarck’s theory of acquired traits?

Need and Fitness • “Need” is not random – individuals who lack an adaptive trait cannot create it … they die. • Fitness: Ability of an organism to survive and reproduce more offspring than the other members of the population in its environment. – The most fit INDIVIDUALS have most SURVIVING offspring.

Who is more fit? A. B. • Has 1 kid • Has 9 kids

Theory of Natural Selection