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Photo by “davemee” flickr creative commons. "nothing in biology makes sense except in the light of evolution” ~Theodosius Dobzhansky (1900-1975). Statements or models that have been tested and confirmed many times. In science, the term "Theory" does not express doubt.
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"nothing in biology makes sense except in the light of evolution”
~Theodosius Dobzhansky (1900-1975)
Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale?
Photo courtesy of ucumari, creative commons, flickr
Blue-footed booby, photo courtesy of stirwise, flickr creative commons
Giant tortoise, photo courtesy of Planetgordon, flickr creative commons
Darwin noted that there existed many finches on the islands, but while they had similarities, each was adapted to eating a particular type of island food
Cactus finch, photo courtesy of zrim, flickr creative commons
Darwin published this work to explain the variety of species that exist on the planet
1. Variation exists among individuals in a species.2. Individuals will compete for resources (food, mates, and space)3. Competition would lead to the death of some individuals while others would survive4. Individuals that had advantageous variations are more likely to survive and reproduce.
This process came to be known as Natural SelectionThe favorable variations are called Adaptations
Photo courtesy of digitalART2, flickr creative commons
Say in a species of blob….there exists blobs of all shapes and sizes (variation)
Blobs eat the little purple organisms that live underground and on the surface.
During a particularly hot year, food became less abundant (competition), blobs that had the ability to dig into the soil to get food had a better chance of survival.
Many blobs died that year…….
The ones that survived mated and passed their genes to the next generation. (reproduction)
The next generation had move blobs with the pointed noses. That is NATURAL SELECTION.
Dinosaurs have always fascinated us, movies such as Jurassic Park capitalize on that fascination.
How do we know what dinosaurs looked like?
We create a picture based on the bones we find (fossils) and use modern reptiles to guess at their texture and skin color.
Homologous structures – these are parts of the body that are similar, but have different functions
ex. The flippers of whales, and the wings of birds
All forelimbs of vertebrates have the same pattern of bones
• Common ancestry
Vestigial Organs – these are organs or parts that seem to have no function
Whales have pelvic bones that do not attach to legs
Lion photo credit: ucumari Tiger photo credit: digitalART2
Embryos of different species develop in almost identical ways.
Human fetus at 8 weeks