How did the tremendous diversity of species presently in existence come into being? Theories: Creationism-according to Bible Intelligent design- higher power Catastrophism-natural disasters Lamarckism-traits acquired during an organism's life can be passed down

Charles Darwin-1831

Darwin’s Theory-Natural Selection Common ancestor, gradual changes lead to speciation Changes were a result of the environment Adaptations may be helpful in one environment, detrimental in another Adaptations may be LOST over time-this is also evolution

Darwin’s Theory-Main Points 1. In any population there are chance variations among organisms-these are NOT produced by the environment but are inherited 2. More individuals are produced than reproduce(overpopulati on, struggle) 3. Individuals that do reproduce are determined by natural selection (survival of the fittest) 4. Over time natural selection may lead to speciation

Evidence for Darwin’s Theory Fossil record Biogeography Homology/compar ative anatomy Biochemical evidence Anatomical evidence Homologous structures Analogous structures Embryological evidence

Examples…. Kettelwell’s peppered moths Pesticide resistance Insecticide resistance

Adaptive Radiation The (relatively) rapid development of one species into many, filling several ecological niches Usually happens in environments that were previously uninhabited or unreachable

Natural Selection In Action