ECOL 182R 1st Edition Lecture 5 Outline of Last Lecture I Levels of Analysis A Mechanism B Development C Function D Evolution II Altruism A Manipulation B Reciprocity C Kin Selection Hamilton s Rule III Instincts Outline of Current Lecture I Early Views of Evolution II What is evolution III Science Religion A Scientific facts vs theories IV What is the evidence for evolution Current Lecture How can we account for The apparent adaptability of these life forms to their environments The diversity of life forms Nothing in biology makes sense except in the light of evolution Th Dobzhansky 1973 The Early Seeds of Evolutionary Thinking Classical view Buffon 1770 Erasmus Darwin 1770 Lamarck 1810 Classical View Living organisms are constant unchanging The root of this notion traces back to the Greeks but even the great naturalist Aristotle pondered over bizarre life forms that he could not easily classify Ex Sponges which look like plants but feed like animals This View Gets Shaken Up Global explorations starting in 1500s turned up extraordinary diversities of life forms some of which appeared related to European forms others with no resemblance Because that view was largely based on organisms in your community The World Distribution of Organisms Was Puzzling Marsupial mammals generally very rare but all Australian mammals were marsupials Cactus plants common in North and South American deserts absent in Australian and Asian deserts If all species were created at the same time in the same place how could so many be restricted to particular parts of the world Buffon If there was only a single spot where species were forms species spreading out from this place would eventually be stopped by mountains or seas So he suggested that the creation of species is spread out in space Also noted that species may have not been created in a perfect state Ex Pigs have lateral toes that are too high to reach the ground He suggested that perhaps species become modified over time Erasmus Darwin Was impressed by diversity of domesticated animals generated by selected breeding Suggested that all organisms had a common ancestor Grandson Charles Darwin later used these ideas Jean Baptiste de Lamarck Suggested that life had been created long ago in simple state and had been gradually improving He proposed a specific mechanism for how this change occurs the inheritance of acquired characteristics Suggested that species change over time that the environment was a factor in this change Species change over time and the environment was a factor in this change What is evolution Charles Darwin defined it as descent with modification He wasn t the first to suggest that evolution occurs but he was the first to suggest a plausible mechanism as well as present an overwhelming case where evolution occurs What do we mean by descent with modification All organisms can be traced back through ancestors Descent with modification allows for tests of evolution Ex If a house has been renovated one or more times if you look hard you can find vestiges of the original house A wall with plasteredover doorframe Scientific Theories and Scientific Facts Gravity as a scientific fact Dropping a pencil doesn t prove gravity What about gravity on other planets Key We can test gravity all the time All experiments designed to test for gravity have been successful Science vs Religion Not incompatible as are designed for different tasks Religion is a system of beliefs generating a set of values and culture Science is a specific tool for asking questions and rigorously testing them Scientists at different faiths still use the same approaches for asking testing questions Many are religious and many people of strong faith still have a deep interest in science Science is about testing The key feature of science is making predictions testing them Testable predictions Hypothesis there is a cold beer in the fridge Science open fridge and see if there is a beer test your hypothesis A strong scientific idea is one that brings order to a set of apparently disparate set of facts In science the burden of faith is on the believer you have to make a case based on repeatable tests that support your assertion Hence you have to put your more fundamental ideas on trail constantly try to prove them wrong Evolution as a scientific fact So if evolution has happened there are tons of signs we should see Key Signatures of shared ancestry Why it s a fact each time we test for evolution we see evidence of it It s the undefeated champ for over 150 years of aggressive testing Ex each new genome sequences is a test of evolution Evidence for descent in modification Biogeography Functional morphology Paleontology fossils Comparative embryology Animal plant breeding Molecular evidence By themselves these things don t make sense With evolution they do Ex Armadillos fossil Glyptodonts Both found in same locations in South America If these had been created separately why would both living and extinct forms be restricted to the same area Darwin thought it made more sense to assume the armadillo evolved from the glyptodont Evidence from Functional Morphology Vestigial Organs Humans have muscles to move their ears Humans have a vestigial tailbone Vestigial toes in the horse Vestigial limbs in whales snakes Homologous structures Why similar blueprints in different organisms Why do a whale s fin a bat s wing a human hand all have similar bones If each was invented for a specific purpose no need to use the same old parts It appears the structures of many organisms are put together with the same pieces Fossils Hard Evidence for Evolution They show a succession from very simple morphological forms early in the fossil record to much more complex forms that appear much later in the fossil record They show multiple examples of transitional forms Direct evidence for descent with modification Two Early Laws of development Haeckel Ontogeny recapitulates phylogeny Embryo passes through stages represented by adult organisms of more primitive species This has been disproved Von Baer s Law Structures that are present in early development are widely distributed among animals while structures that are present in late development are less widely distributed So says that features that distinguish between different species tend to arise later in development Evidence from animal breeding Darwin was impressed by how much domesticated animals had been changed by artificial selection Ex breeds of dogs