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- Evolution - - Evolution The English noun evolution (from Latin ēvolūtiō "unfolding, unrolling") refers to any kind of gradual change. - Evolution “nothing in biology makes sense except in the light of evolution” Theodosius Dobzhansky (1900-1975) Darwin’s Return Darwin’s Return • Darwin returned to England in 1836 and brought the specimens he had collected from around the world. Darwin’s Return • Darwin returned to England in 1836 and brought the specimens he had collected from around the world. • He made some remarkable discoveries about some of these specimens. Darwin’s Return • He made some remarkable discoveries about some of these specimens. Darwin’s Return • He made some remarkable discoveries about some of these specimens. • One was that all the birds he had collected on the Galapagos turned out to be finches. Darwin’s Return • There were other examples too, of animals found on the Galapagos, but nowhere else. • He made some remarkable discoveries about some of these specimens. • One was that all the birds he had collected on the Galapagos turned out to be finches. Darwin’s Return • There were other examples too, of animals found on the Galapagos, but nowhere else. • He began to work on making sense of these findings. Darwin’s Return • There were other examples too, of animals found on the Galapagos, but nowhere else. • He began to work on making sense of these findings. • He spent the next 23 years putting together his theory. Darwin’s Return • He spent the next 23 years putting together his theory. • In 1859 he published On the Origin of Species. The Big Idea The Big Idea • Response to Darwin’s work was very divided. The Big Idea • Response to Darwin’s work was very divided. • Some people thought it was brilliant, while others were strongly opposed. The Big Idea • Response to Darwin’s work was very divided. • Some people thought it was brilliant, while others were strongly opposed. • A situation that is not that different from today. The Big Idea • What exactly is in that book anyway? What the heck! • Darwin’s Theory of Evolution can be summed up as follows: The Big Idea 1) Individual organisms differ, and some of this variation is heritable. The Big Idea 1) Individual organisms differ, and some of this variation is heritable. The Big Idea 1) Individual organisms differ, and some of this variation is heritable. • Darwin noticed that animal breeders used heritable variation to produce animals with desirable characteristics. The Big Idea 1) Individual organisms differ, and some of this variation is heritable. • Darwin noticed that animal breeders used heritable variation to produce animals with desirable characteristics. • Called Artificial Selection, nature provided the variation, and humans selected the variations they found useful. The Big Idea • Darwin was convinced a process like artificial selection was at work in nature. The Big Idea • Darwin was convinced a process like artificial selection was at work in nature. • Darwin recalled the work of Malthus on population growth – having too many offspring to all survive would result in a competition for resources. The Big Idea • Darwin was convinced a process like artificial selection was at work in nature. • Darwin recalled the work of Malthus on population growth – having too many offspring to all survive would result in a competition for resources. • Which ones, Darwin wondered, would be the most likely to survive and reproduce? The Big Idea 2) Individuals best suited to their environment survive and reproduce most successfully. The Big Idea 2) Individuals best suited to their environment survive and reproduce most successfully. The Big Idea 2) Individuals best suited to their environment survive and reproduce most successfully. • This was Darwin’s Big Idea – that nature will select the characteristics that make the organism the “most fit”. The Big Idea 2) Individuals best suited to their environment survive and reproduce most successfully. • This was Darwin’s Big Idea – that nature will select the characteristics that make the organism the “most fit”. • He called this Natural Selection The Big Idea 2) Individuals best suited to their environment survive and reproduce most successfully. • This was Darwin’s Big Idea – that nature will select the characteristics that make the organism the “most fit”. • He called this Natural Selection • Only organisms most fit for their environment will pass on their genes. The Big Idea 2) Individuals best suited to their environment survive and reproduce most successfully. • This was Darwin’s Big Idea – that nature will select the characteristics that make the organism the “most fit”. • He called this Natural Selection • Only organisms most fit for their environment will pass on their genes. The Big Idea 3) Species alive today “descended with modification” from species that lived in the distant past. The Big Idea 3) Species alive today “descended with modification” from species that lived in the distant past. • This process, unites all organisms on Earth into a single tree of life. The Big Idea 3) Species alive today “descended with modification” from species that lived in the distant past. • This process, unites all organisms on Earth into a single tree of life. Video The Big Idea 3) Species alive today “descended with modification” from species that lived in the distant past. • This process, unites all organisms on Earth into a single tree of life. Video Video 2 The End of Part II