Evolution.pdf

Evolution What is Evolution? change in the hereditary characteristics of groups of organisms over the course of generations branching of lineages, and changes within lineages “descent with modification”, On the Origin of Species oftenly conflated with natural selection the...

Evolution What is Evolution? change in the hereditary characteristics of groups of organisms over the course of generations branching of lineages, and changes within lineages “descent with modification”, On the Origin of Species oftenly conflated with natural selection the historical occurrence of change Natural Selection - is one mechanism, in most cases the most important, that can cause evolution Development of the Theory of Evolution - Darwin and Wallace - descent with modification (which was not new to the world) and natural selection as the mechanism of evolution (this was their unique contribution)  ❖ Population pressures and the idea that They had many influences: populations will run out of resources before they stop overproducing offspring ❖ The concept of species’ ability to (Malthus) change (Buffon, Lamarck, and Erasmus Darwin) ❖ Gradual geological change and uniformitarianism (Hutton and Lyell) ❖ Biogeography, or the distribution of species across the globe (de Candolle, Humboldt, and Hooker) ❖ Well-studied fossils and extinct species (Cuvier) ❖ Taxonomic classification and hierarchy (Linnaeus) ❖ Comparative anatomy and embryology (Huxley, Owen, and Saint-Hillaire) Personal Influences on Darwin Time on the HMS Beagle Darwin was hired as an educated companion and naturalist for the captain of this small ship, on the recommendation of his professors He spent 5 years on this ship and sailed a route that was literally around the world. Formative experiences aboard the ship: Darwin was in the Andes Upon visiting islands, His first look at during a major earthquake Darwin began to see tropical diversity was that unearthed some fossils how species changed at a stop near Rio, that he recognized as related from a common Brazil, where the to living species. The uplift also ancestor that exuberance of made him consider geologic colonized the island biodiversity blew his change (Lyell’s influence) mind!  Darwin’s Finches He studied 14 species, Darwin thought that The finches are a about half of the the finches were good example of species present on many species, such as adaptive radiation the Galapagos Island grosbeaks and blackbirds, but upon returning to England, an ornithologist pointed out to him that they were all finches Big numbers catch your audience’s attention  Alfred Russel Wallace Unlike Darwin, Went to the After returning to Britain, One paper Wallace sent his paper Wallace came he traveled to the Indo- Amazon after outlined the on evolution by natural Malay archipelago for 8 from humble Darwin had Sarawak Law, or selection to Darwin, years. backgrounds and returned from his “Every species has which immediately started his work voyages on The While there, and shaking come to existence pushed him to publish as a naturalist Beagle and lost his with Malaria, he coincident both in a summary of his own collecting entire collection remembered the works time and space work alongside of Thomas Malthus specimens to sell due to a boat fire with a pre- Wallace’s. (population studies) and to gentlemen wrote two papers that he existing, closely collectors sent back to England related allied species”— Evidence for Evolution  Comparative anatomy Genetics and fossil record Molecular Biology Comparative Anatomy - is the study of anatomical similarities and differences among species For example, what does your arm have in common with the wing of a bird, the flipper of a porpoise, and the forelimb of an elephant? Homologous structures - structures shared by related species and that are inherited from a common ancestor - have a common origin, but do not necessarily perform the same function. Analogous structures - body parts that share a common function, but not structure, - serve the same function but come from different origins Comparative Anatomy Another way to compare the anatomy of different species is to compare their embryos  Genetics and Molecular Biology Species that share more Scientists compare the Scientists hypothesize that similarities in their DNA DNA base sequences of if two species have base sequences are more different species to similarities in their base closely related than those determine evolutionary sequences, they share a that share fewer relationships. common ancestor. similarities.  The greater the number of differences in base sequences the farther the base sequences, the farther the evolutionary distance from humans.  A fossil is a remnant or trace of an Fossils organism from the past, such as a skeleton or leaf imprint, embedded and preserved in Earth’s crust. Much of the evidence for evolution comes from studying fossils.  - Many fossils are formed from the hard parts of an organism’s body like bones and teeth. - Fossil formation begins when an organism’s body is quickly How fossils are covered in sediments from an event like a mudslide or a sand formed. storm. - Over time, more and more sediments cover the remains. - After a long time, the chemicals in the body parts are replaced with rock replaced with rocklike minerals. - This process results in a heavy, rock-like copy of the original object—a fossil.  Fossils found in the upper (newer) sedimentary layers more closely resemble present-day organisms than fossils found in deeper (older) layers. Fossils  MISCONCEPTIONS “Evolution is like a climb EVOLUTION IS A THEORY Evolution means that life up a ladder of progress; ABOUT THE “ORIGIN OF changed “by organisms are always LIFE” chance”. getting better.” “Natural selection “Natural selection gives “Evolution is 'just' a involves organisms organisms theory.” 'tryingʼ to adapt.” what they 'need.ʼ ”  MISCONCEPTIONS “Evolution is a theory in “Gaps in the fossil record “The theory of evolution crisis and is collapsing as disprove is flawed, but scientists scientists lose evolution.” wonʼt admit it.” confidence in it.” “Evolution is not science “Most biologists have Evolution and religion because it is not rejected 'Darwinism' (i.e., are opposing ideas observable or testable.” no longer really agree with the ideas put forth by Darwin and Wallace).”