Darwin Evolution by Natural Selection ch he fin
Darwin & Evolution by Natural Selection ch he fin c ee Tr fin Insect eaters Regents Biology es Seed eaters Bud eater nd Cactus eater ou Gr s er Warbl finch 2006 -2007
Charles Darwin § Proposed a way how evolution works How did creatures change over time? u by natural selection u § Collected a lot of evidence to support his ideas 1809 -1882 u British naturalist u Regents Biology
Voyage of the HMS Beagle § Invited to travel around the world 1831 -1836 (22 years old!) u makes many observations of nature u § main mission of the Beagle was to chart South American coastline Robert Fitzroy Regents Biology
Voyage of the HMS Beagle § Stopped in Galapagos Islands u 500 miles off coast of Ecuador Regents Biology
Galapagos Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland. Regents Biology 800 km west of Ecuador
Darwin found…many unique species Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands? Regents Biology
Darwin found…clues in the fossils Darwin found: Evidence that creatures have changed over time present day Armadillos Darwin asked: ancient Armadillo Regents Biology Why should extinct armadillos & modern armadillos be found on same continent?
Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like? Regents Biology
Darwin found… birds Darwin found: Many different birds on the Galapagos Islands. He thought he found Finch? very different kinds… Regents Biology Woodpecker? Sparrow? Warbler?
But Darwin found… a lot of finches Darwin was amazed to find out: All 14 species of birds were finches… But there is only one species of finch on the mainland! Large ground Finch? finch Small. Sparrow? ground finch Sparrow? Darwin asked: If the Galapagos finches came from the mainland, why are they so different now? Regents Biology Warbler finch Woodpecker? Tree finch Warbler?
The finches cinched it! n different beaks are Darwin found: inherited variations The differences n serve as adaptations between species of that help birds said: compete Darwin finches were for food associated with the Ahaaaa! n these birds survive & different food they ate. Aeater flock of Small South Big Large seed ground Small ground seed eater finch Finch? Sparrow? n n Regents Biology reproduce finch American finches pass on the genes for were stranded on the those more fit beaks Galapagos… over time nature selected for different species with different beaks Warbler Insect eater finch Woodpecker? Leaf Tree & bud finch eater Warbler?
Relationship between species (beaks) & food Regents Biology
Darwin’s finches § Darwin’s conclusions u variations in beaks § differences in beaks in the original flock § adaptations to foods available on islands u natural selection for most fit § over many generations, the finches were selected for specific beaks & behaviors u offspring inherit successful traits § accumulation of winning traits: both beaks & behaviors u separate into different species Regents Biology
From 1 species to 14 species… Warbler finch Cactus finch Woodpecker finch Small ground finch ch fin c ee Tr fin Insect eaters variation Regents Biology Bud eater es Seed eaters Vegetarian tree finch nd Cactus eater ou he s er Warbl finch Gr Small insectivorous tree finch Large insectivorous tree finch Sharp-beaked finch Medium ground finch Large ground finch natural selection for best survival & reproduction
Earlier ideas on Evolution § La. Marck u evolution by acquired traits § creatures developed traits during their lifetime § give those traits to their offspring u example § in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring u not accepted as valid Regents Biology
Darwin’s view of Evolution § Darwin giraffes that already have long necks survive better u leave more offspring who inherit their long necks § variation § selection & u survival § reproduction & inheritance of Regents Biologymore fit traits
Asking Questions is a good adaptation! Regents Biology 2006 -2007
Darwin found… more fossils Darwin found: Evidence that creatures have changed over time present day Sloth (extinct) Giant ground sloth Regents Biology Darwin asked: Why should extinct sloths & modern sloths be found on the same continent?
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