Chapter 15 Darwin’s Theory of Evolution

Darwin’s Voyage On the Beagle, around the world On the Beagle, around the world Found the Galapagos Islands most interesting Found the Galapagos Islands most interesting Made Observations based on: Made Observations based on: –Patterns of diversity –Fossils

Ideas that Influenced Darwin Hutton and Lyell – geological changes and the age of the Earth Hutton and Lyell – geological changes and the age of the Earth Lamarck’s theory of acquired traits Lamarck’s theory of acquired traits Malthus- population growth and its demands Malthus- population growth and its demands

Darwin’s Theory of Evolution Wrote On The Origin of Species in 1859 Wrote On The Origin of Species in 1859 Evolution by natural selection: favorable traits already inherited enabled a species to survive and reproduce. Evolution by natural selection: favorable traits already inherited enabled a species to survive and reproduce.

Evidence for Evolution Fossil record Fossil record Geographic distribution of living things Geographic distribution of living things Homologous body structures Homologous body structures Homologous body structures Homologous body structures Vestigial structures. examples Vestigial structures. examples Vestigial structuresexamples Vestigial structuresexamples Similarities in embryology Similarities in embryology

Summary of Darwin’s Theory Individual organisms differ and some of this variation is inheritable. Individual organisms differ and some of this variation is inheritable. Organisms produce more offspring than can survive. Organisms produce more offspring than can survive. Those that survive compete for resources. Those that survive compete for resources. In the struggle for existence, individuals best suited to their environment survive and reproduce, thus passing on their favorable traits (natural selection). In the struggle for existence, individuals best suited to their environment survive and reproduce, thus passing on their favorable traits (natural selection).

Strengths and Weaknesses of Evolutionary Theory Offers vital insights to biological and biomedical sciences. Offers vital insights to biological and biomedical sciences. Researchers still debate about how new species arise and how some become extinct. Researchers still debate about how new species arise and how some become extinct. There is also uncertainty about how life began. There is also uncertainty about how life began.