The Modern Theory of The Modern Theory of EvolutionEvolution

Mr. ModafferiMr. Modafferi

Do NowDo Now

• What did Lamarck believe?What did Lamarck believe?

Darwin’s JourneyDarwin’s Journey

The Galapagos IslandsThe Galapagos Islands

• Volcanic islands off the South Volcanic islands off the South American coastAmerican coast

• Island species varied from the Island species varied from the mainland species, and from mainland species, and from island-to-islandisland-to-island– Example: Each island had either long or Example: Each island had either long or

short necked tortoises depending on the short necked tortoises depending on the island’s vegetation (Their shells also island’s vegetation (Their shells also varied)varied)

Finches!Finches!

• Finches on the Galapagos Islands Finches on the Galapagos Islands resembled a mainland finch, but resembled a mainland finch, but there were more typesthere were more types

• Bill shapes are adaptations to Bill shapes are adaptations to different means of gathering food.different means of gathering food.

• Galapagos finch species varied by Galapagos finch species varied by nesting site, beak size, and eating nesting site, beak size, and eating habits.habits.

Think BIGGER!Think BIGGER!• Newer species are just Newer species are just

descendants of older speciesdescendants of older species

GEICO Cave Man

Mr. Modafferi

Why are there different Why are there different species?species?

• Darwin believes that once the Darwin believes that once the organisms got to the island they organisms got to the island they reproduced, and eventually their reproduced, and eventually their offspring became different than the offspring became different than the original mainland animalsoriginal mainland animals

• Evolution is linked to genes that Evolution is linked to genes that are passed on through are passed on through reproduction!reproduction!

AdaptationAdaptation• Adaptation - is a trait that helps an Adaptation - is a trait that helps an

organism be more suited to its organism be more suited to its environmentenvironment

How and When do These How and When do These Changes/Adaptations Changes/Adaptations OccurOccur• Evolutionary changes occur over Evolutionary changes occur over

time time

• Evolutionary change only occurs Evolutionary change only occurs in the genes of sex cells in the genes of sex cells

• Adaptations can be in structure, Adaptations can be in structure, function, and behavior over time function, and behavior over time

Question of the Day Question of the Day

• Why do you think a species would Why do you think a species would change?change?– Why are there different turtles on the Why are there different turtles on the

Galapagos Islands?Galapagos Islands?– Why are there different Finches on Why are there different Finches on

South America and the Galapagos South America and the Galapagos Islands? Islands?

Natural SelectionNatural Selection

• Natural Selection = Survival of the FittestNatural Selection = Survival of the Fittest

• This is the major idea to the modern This is the major idea to the modern theory of evolutiontheory of evolution

Natural Selection Cont.Natural Selection Cont.

• The environment acts as the The environment acts as the selecting agentselecting agent

• Natural occurring variations among Natural occurring variations among members of a population make some members of a population make some of them better adapted to the of them better adapted to the environment to survive.environment to survive.

HomeworkHomework

• Finish WorksheetFinish Worksheet