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Transcript
Cues Paleo-4 Notes Darwin & Evolution What is evolution? What is a species? Differentiate between a variation and an adaptation? evolution - change in the hereditary characteristics of groups of organisms over the course of generations. (Darwin called this process "decent with modification".) species – a group of similar organisms that can mate with each other and produce fertile offspring. variation - genetically determined differences in the characteristics of members of the same species. adaptation – a trait that helps an organism survive and reproduce. The Theory of Biological Evolution draws on evidence of observations of the fossil record, genetic information, the distribution of plants and animals, and the similarities across species of anatomy and development. The Darwin Story The Gathering of Observations The Trip Begins– December of 1831 the HMS Beagle leaves England for a 5 yr. Voyage around the world with 22 year-old Charles Darwin who became the ship’s naturalist. The Observations: - In Brazil: insects that looked like flowers, and army-like ants. - In Argentina: armadillos, sloths and bones that resembled the sloth, but with variations - In the Galapagos Islands: - giant tortoises with different shells on different islands - seals covered with fur - lizards that only ate prickly cacti - small differences in birds of the same family - plants that were similar to those he’d collected on the mainland. - cormorants on the mainland - could fly / on the island - Name one example of adaptations Darwin observed during his voyage on the HMS Beagle? What is Darwin’s theory of natural selection? What does his theory have to do with the term evolution? What other scientist had similar ideas to those of Darwin? Darwin proposed that changes in organisms occur continuously and slowly over time – called gradualism. 100 years later, after many scientists have examined the fossil record, Gould & Eldredge proposed a different theory. What was it called and how did it differ from gradualism? couldn’t - differences in the claws of iguanas - finches with 14 variations in beaks for different foods The Theory – After he got back to England, Darwin consulted with other scientists about what he saw for over 20 years before he published his theory of natural selection, The Origin of the Species, in 1859. Darwin discovered that the idea of natural selection ( a process by which individuals that are better adapted to their environment are more likely to survive and reproduce) was not exclusively his. Alfred Russell Wallace (1823-1913), a young naturalist, had developed similar ideas in an essay called "On the Tendency of Varieties to Depart Independently from the Original Type." Wallace sent this paper to Darwin for an opinion. Darwin took Wallace's manuscript to a friend, Sir Charles Lyell, who decided that both Wallace's and Darwin's ideas should be presented at the same time. On July 1, 1858, both papers were read at a meeting of the Linnaean Society of London. They felt biological evolution took place gradually. In recent years, Gould & Eldredge's "punctuated equilibrium" theory proposes that the changes happen more rapidly due to “catastrophes in the environment. Gradualism What three factors can affect natural selection? Punctuated Equilibrium 3 factors affecting Natural Selection: 1) Overproduction – not enough resources (food, water, etc.) for the number born. 2) Competition – those who don’t get the limited supplies of food and water die. 3) Variations – a difference between individuals of the same species. The role of genes in evolution of organisms was unknown to What role do genes play in Darwin. It was almost 100 years before scientists discovered evolution? that these changes could come from gene mutations of shuffling of alleles during meiosis. What is one way a new species could form? How do new species form? One way is by geographic isolation of a species, where a species could be separated into two different environments on a local level (disasters) or worldwide (plate tectonics). Summaries