Darwins Voyage of Discovery Charles Darwin Born February

Darwin’s Voyage of Discovery

Charles Darwin • Born February 12, 1809 in England • Grew up when scientific views were shifting – Geologists suggested that Earth was ancient and had changed over time – Biologists suggested that life on Earth had also changed • Evolution = the process of change over time

• Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors. • 1831 invited to sail on HMS Beagle’s 5 -year voyage mapping the coast of South America • Darwin planned on collecting specimens of plants and animals

Observations aboard the Beagle 3 distinctive patterns of biodiversity 1. Species vary globally 2. Species vary locally 3. Species vary over time

Species vary globally • Darwin noticed that different, yet ecologically similar, animal species inhabited separated, but ecologically similar, habitats around the globe. – Rheas in grasslands of S. America – Ostriches in grasslands of Africa – Emu in grasslands of Australia

Species vary globally Why did different flightless birds live in • Noticed that there were no rabbits in the similar grasslands America grasslands of Why like werethe there no acrossof. S. S. America, Europe. rabbits in Australia, and Africa, and no kangaroos but notgrasslands in Northern • Australia’s were home toin England? Hemisphere? kangaroos and other animals that were not found any where else. • What did these patterns of geographic distribution mean?

Species vary locally • Darwin noticed that different, yet related, animal species often occupied different habitats within a local area. • Rheas: 2 species- one in Argentina’s grasslands, one in cooler scrubland south • Galapagos: tortoise shells varied from island to island • Different varieties of mockingbirds • Finches with different shaped beaks

Giant Tortoise • Galapagos: tortoise shells varied from island to island • Those that live on the larger islands where there is more rain have “dome” shaped shells, while those that live in drier conditions are smaller tortoises and have a “saddleback” shell.

Mockingbirds

Finches

Species vary over time • Darwin noticed that some fossils of extinct animals were similar to living species. • Glyptodon – Similar to present day armadillo

Putting the Puzzle Pieces Together • Darwin began to wonder whether different Galapagos species might have evolved from South American ancestors. • He spent years researching ideas about species and evolution • The evidence suggested that species are not fixed and that they could change from some natural process