Theory of Evolution Chapter 22 Evolution is the gradual change of genes and populations over time Old Theories 1 Lamarck 1700 s People believed in the idea of acquired characteristics traits you get during your lifetime can be passed on to children We know now that our traits are determined by our GENES not what we do during our lifetime 2 Divine Creation Everything living on Earth has always been and was exposed to no change Every living thing individually created by God at one moment of creation 3 Georges Cuvier 1700 s He appreciated fossils but opposed the idea of species changing over time He theorized that the strata of fossils he discovered were caused by multiple catastrophes in Earth s history 4 Charles Darwin 1830 s New ideas on how living things change over time He traveled to the Galapagos Island off South America on the found fossils determined that living things can come from a common ancestor but develop new traits due in their environment living things can die out and be replaced by others As Darwin went from island to island on the Galapagos he notices that animals seemed closely related BUT had different characteristics such as the giant turtles the fossils evidence printed to a common ancestor but over time The turtles had developed different traits The organisms best suited for their environment get to survive and pass out on their genes to their offspring he called his theory Natural Selection the environment puts pressure on living things to survive and those who fit in can live and pass on their genes Adaptations are the key to an organism s survival Lonesome George died June 24 2012 at 100 years old The environment plays a role in natural selection but does NOT cause the changes The environment puts pressure on living things to survive Survival depends on the traits the organism has and that is determine by DNA Whoever survives the best gets to reproduce and transfer their traits to future generations Evolutions explains the diversity of life on Earth and also the similarity Each island in the Galapagos had a different species of finch They have developed different traits to adapt to their surroundings DNA tests have shown that these different looking bird share some DNA which mean they have an ancestor in common but have developed different traits over time Other Evidence that Supports Natural Selection 1 Phenotypic changes in the organism due to environmental pressure Ex England s Peppered Moth 2 Genetic Mutations can create new phenotypes 3 Selective Breeding All dog breeds are the same species descended from wolf ancestors 4 Sexual reproduction leads to variety in traits 5 Accidental Selection Using chemicals like DDT can select for resistant insects Many strains of bacteria are no longer killed by antibiotics 6 Comparative Embryology Animals with an ancestral connections similar DNA have similar development 7 Vestigial Structures Body parts no longer used but might have served a purpose in ancestors a Appendix in humans b leg bones spurs in snakes like Clyde 8 Homologous Structures similar structures and different functions 9 Analogous Structures similar functions and different structures 10 DNA comparisons Organisms with similar DNA point to having a common ancestors a With humans we are primates like Gorilla and Chimps Our DNA is 99 identical to chimpanzees That 1 is a huge amount that makes use human 11 Biogeography The geographical distribution of species Islands being isolated from other areas have species called endemics species found nowhere else but are closely related to species on the mainland
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