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7.4 The Evidence for Evolution. Pages 296-302. biogeography. The study of the distribution of organisms. Galapagos Islands. Darwin on the HMS Beagle. 1831-1836 Galapagos Islands, 1000 km off the west coast of S. America No large land mammals or amphibians
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7.4 The Evidence for Evolution Pages 296-302
biogeography • The study of the distribution of organisms
Darwin on the HMS Beagle • 1831-1836 • Galapagos Islands, 1000 km off the west coast of S. America • No large land mammals or amphibians • Strange reptiles, birds, insects and plants, similar to those found on nearest continent
No fear!! • Birds land on your head. • Iguanas allow you to pick them up. • Sea lions sit beside you. loss of instinctive fear?
Unique species • Arrived by water or air then changed into new species over time
Comparing iguanas • Mainland iguanas have short claws for climbing trees. • Galapagos iguanas have long claws for hanging onto slippery rocks.
Homologous Features • A structure with a common evolutionary origin currently used in different ways.
Mammals • 7 neck bones
Mammals • 28 skull bones
Skeletons • Bat skeleton Human skeleton
Homologous embryonic development • Human embryos have gill slits.
Analogous Features • Body parts that perform the same function but do not share similar origin or structure fly eye rabbit eye
Analogous features Dragon fly wing vs. bird wing
Vestigial features Dew toes in dogs hip bones in whales
Thomas Malthus The Principle of Population All populations were limited in size by their environment—and in particular their food supply.