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Transcript
SBI 3U Ms. Girvan Date: ___________________ History of Evolutionary Thought I. Early Philosophies - Plato believed that organism existed in an unchanging ideal form - Aristotle categorized all living things and felt that organisms fit into an orderly scheme called the ______________________________ (Ladder of Nature) - Aristotle believed that all organisms that ever would exist were already created permanent and perfect II. George-Louis Leclerc, Comte de Buffon (1707-1788) - publicly challenged the idea that life forms were unchanging - noted similarities between humans and apes (speculated on ______________________________________________) - suggested species change over time and the Earth was much older than _________________ years III. Georges Cuvier (1769-1832) - developed science of ________________________________ (study of ancient life through examination of fossils) - found each layer (stratum) of rock is characterized by a unique group of fossil species - also found that deeper fossils were more dissimilar to modern life - discovered that new species appeared and others disappeared over the passage of time (showed that species could become extinct) - proposed theory of catastrophism Catastrophism 1 IV. Charles Lyell (1797-1875) - geologist who rejected catastrophism - proposed theory of uniformitarianism based on geologist James Hutton’s work Uniformitarianism - theorized that slow, subtle processes could happen over a long period of time and could result in substantial changes V. Jean-Baptiste Lamarck (1744-1829) - believed that species increased in complexity over time, until they achieved a level of perfection - hypothesized that organisms would become progressively better adapted to their environments - also suggested body parts not used would eventually disappear Inheritance of Acquired Characteristics 2 this theory was ultimately disproved, especially after discoveries were made about genetics and how traits were inherited V. Charles Darwin (1809-1882) - in 1831, he set off on a five year voyage on the H.M.S Beagle as the ship’s naturalist - he collected specimens and took observations of the organisms he encountered - some of his observations Table 8.1 (p.329) - flora and fauna of different regions were distinct from those in England and Europe - fossils of extinct animals that looked very similar to living animals - finches and other animals on Galapagos Islands closely resembled animals he had observed on west coast of South America - Galapagos species (tortoises & finches) looked identical at first, but actually varied slightly between islands VI. Darwin and Wallace – The Theory of Evolution by Natural Selection - Alfred Russel Wallace (1823-1913) reached conclusions similar to Darwin - both naturalists suggested that organisms tend to produce more offspring than can survive - some organisms would be more “fit” to survive than others, and the fittest organisms would pass on those traits to their offspring - competition for limited resources between individuals of the same species would select for individuals with favourable traits - “survival of the fittest” VII. The Origin of Species – by Charles Darwin - published in 1859 - proposed that all life descended from an unknown organism 3 - descendants spread out and developed adaptations that helped them better survive in their local environments Main ideas: o Organisms produce more offspring than can survive, therefore there is competition for resources (food, space, etc…) o Individuals of a population vary extensively, and much of this variation is heritable o Individuals who are better suited to local conditions survive to produce more offspring o Process for change are slow and gradual - coined the term natural selection: - Darwin did not use the term evolution in the original edition of his book - he spoke of descent with modification as he felt evolution implied progress - natural selection has NO set direction 4