EVOLUTION Chapter 15

Charles Darwin

Darwin’s Theory of Evolution Evolution: Change over time, This is why certain animals blend in or have long beaks A scientific theory is a well-supported testable explanation that occurred in the natural world

Voyage of the Beagle

Patterns of Diversity Darwin visited Argentina and Australia which had similar grassland ecosystems. those grasslands were inhabited by very different animals. neither Argentina nor Australia was home to the sorts of animals that lived in European grasslands.

Patterns of Diversity Darwin posed challenging questions. Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them? Why were there no kangaroos in England?

Living Organisms and Fossils Darwin collected the preserved remains of ancient organisms, called fossils. Fossil: Petrified (Turned to stone) organic material Some of those fossils resembled organisms that were still alive today.

Fossils

The Galapagos Island The smallest, lowest islands were hot, dry, and nearly barren-Hood Island-sparse vegetation The higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation.

Animals found in the Galapagos Land Tortoises Darwin Finches Blue-Footed Booby Marine Iguanas

Animals

The Journey Home Darwin Observed that characteristics of many plants and animals vary greatly among the islands Hypothesis: Separate species may have arose from an original ancestor

Lamarck’s Evolution Hypothesis By selective use of certain organs, organisms lose or gain traits. These traits get passed on to their offspring

Lamarck’s Evolution Hypothesis Proposed that by selective use of certain organs, organisms lose or gain traits. These traits get passed on to their offspring

Lamarck’s Evolution Hypothesis Proposed that by selective use of certain organs, organisms lose or gain traits. These traits get passed on to their offspring What’s wrong with this hypothesis?

What they forgot Did not account for how the traits were inherited. Animals behavior does not determine their inherited traits.

Natural Selection Animals best adapted to environment will survive and reproduce

Natural Selection

Natural Selection

Artificial Selection Nature provides the variation, humans select what we find useful Those plants or animals pass on those traits

Struggle for Existence

Struggle for Existence Members of each species compete regularly to obtain food, living space and other resources Animals with best Fitness, would adapt better and increase chances of survival

Common Descent Over Millions of years, organisms evolved from same ancestor

Homologous Structures Structures that have different forms but develop from same embryonic tissue

Vestigial Organs Organs that no longer serve a purpose, but at one point did. Appendix, tails, toes