Species Species: group of organisms that can interbreed and produce fertile offspring –Different species rarely breed –Interspecies breeding often results in sterile offspring Ex: Horse x Donkey = Mule Ex: Lion x Tiger = Liger –When new species? no longer able to reproduce sucessfully

Acquired Inheritance: Early theory where organisms could acquire and pass traits after birth Early Belief: Giraffes got long neck by stretching Problem: Traits acquired after fertilization cannot be passed to offspring

Geologic Change Early belief: –Earth ~6,000 years old –Life remained unchanged “New” Observations –Rock layers (strata) contained differing fossils –Deeper fossils less complex –Environments changes as continents drift –Uniformitarianism: geologic processes that shape earth are uniform

Charles Darwin Observed: –Organisms have variations based upon environment –Similarities between extinct fossils & modern life –Marine fossils atop mountains Natural Selection: Process where organisms with favorable traits survive and reproduce Published in The Origin of Species (1859)

Adaptation & Variation Variation: Inherited traits that make an individual different from others –Green, flat wings of the insect above Adaptation: Variation increases the chance of survival –Ability to blend with environment

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1)When are two organisms considered a different species? 2)Even though incorrect, why is Lamarck’s theory still relevant? 3)How can the general age of rocks (and fossils) be determined? 4)How does a variation and adaptation differ? 5)What is natural selection? Kobe Kuiz