Evolution (10.1-10.3) Goal: Be able to explain and give examples of the evidence that led Charles Darwin to form his Theory of Evolution

Jean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck Jean Baptiste Lamarck Fossil creatures didn’t go extinct...they changed into modern creatures. Called this change “Evolution”- Jean Baptiste Pierre Antoine de Monet, Chevalier de Lamarck

Jean Baptiste Lamarck Suggested a possible mechanism for evolution- The Theory of Acquired Characteristics (1801) - Organisms vary in their characteristics - Characteristics that get used more, develop more, those that don’t, get reduced. (USE IT OR LOSE IT) - Characteristics that develop in an individual get passed onto offspring.

Jean Baptiste Lamarck According to his theory: Giraffes have long necks because ancestors strained to reach leaves in trees. The strain made their necks stretch out a little, and their offspring were born with slightly longer necks. Over many generations, longer and longer necks developed.

Jean Baptiste Lamarck

In 1883, August Weismann.. 901 mice later…..still nothing but sad mice…

Charles Darwin Suspected that Lamarck’s theory was wrong, they independently came up with a different mechanism for evolution

Charles Darwin The Theory of Natural Selection (1859) Revised mechanism for evolution- The Theory of Natural Selection (1859) - Organisms vary in their characteristics - Organisms produce more offspring than can possibly survive. - Organisms always struggle for food, habitat, protection and mates. - Organisms that vary in ways that make them better adapted to their surroundings produce more offspring. Favorable characteristics will accumulate (Nature Selects). -AKA variation, competition, adaptation, descent with modification

Darwin’s Theory… Is also called “survival of the fittest” Fitness: a measure of the ability to survive and produce more offspring relative to other members of the population in a given environment.

Charles Darwin According to this theory: Giraffe ancestors had small variations in neck lengths. Those with slightly longer necks could get more food, were healthier, and had more offspring. The offspring carried the traits for long necks. Over many generations of longer necks having an advantage, modern giraffes developed.

Lamarck VS. Darwin

Variation among species Species change throughout their lifetime Species do not change throughout their lifetime Differential survival No extinction Use it or lose it Survival of the fittest