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Darwinism. The Origin of the Species by Natural Selection. Plato. Believed there were two worlds A real world that is ideal and eternal An illusory world of imperfection perceived by senses. Aristotle.
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Darwinism The Origin of the Species by Natural Selection
Plato • Believed there were two worlds • A real world that is ideal and eternal • An illusory world of imperfection perceived by senses
Aristotle • Believed that all living forms could be arranged on a scale of increasing complexity. This was known as scala naturae.
Charles Darwin • Son of a prominent physician in England • At age 16 his father sent him to the University of Edinburgh to study medicine • Enrolled at Christ College at Cambridge to become a clergyman • In December of 1831 at the age of 22 he sailed with the crew of the HMS Beagle • 1844 – Wrote a long essay on the origin of species by natural selection • 1859 – Published The Origin of the Species by Natural Selection
Summary of Darwin’s Ideas • Natural Selection is the differential success in reproduction, and its product is adaptation of organisms to their environment • Natural selection occurs from the interaction between environment and the inherent variability in a population
Variations in a population arise by chance but natural selection is not a chance phenomenon, since environmental factors set definite criteria for reproductive success. • Variation and overproduction make natural selection possible
Examples of Natural Selection in Action • Average beak depth varies with rainfall • Butterfly population adapted to a vegetation change in a ten year period • Antibiotic resistant bacteria
The Evidences for Evolution Fossil Evidence Comparative Anatomy Artificial Selection Embryology Comparative Biochemistry Biogeography
Figure 22.2 Fossils of trilobites, animals that lived in the seas hundreds of millions of years ago