Transcript of Slides History of Evolution Darwin Natural Selection Human Evolution Dr Chiu Slide 2 organic matter The process of evolution explains diversity distribution and origins of Evolution is basically defined as common descent with modification Slide 3 Remember the tree thinking exercise Lineages diverge from a shared common ancestor a node Lineages consist of extinct and extant living members Slide 4 record and is what we can observe It occurs over large timescales Macroevolution is the level of evolution that is reflected in the fossil Slide 5 the world as a dynamic entity There was a change in how people view the world Today scientists view Slide 6 FIGURE 2 4 James Hutton Hutton here depicted ca 1790 founded modern geology with his theory of the earth s formation Hutton realized that the same natural processes he observed in Scotland had occurred in the past Slide 7 FIGURE 2 6 Charles Lyell Lyell here depicted ca 1845 rediscovered Hutton s work and the idea of uniformitarianism Lyell s research based on examinations of geologic strata confirmed Hutton s estimate of Earth s very old age Slide 8 FIGURE 2 5 Geologic Strata The succession of strata from oldest at the bottom to youngest at the top as here in Utah s Bryce Canyon marks the formation of new land surfaces over time Slides 9 FIGURE 2 8a Georges Cuvier Transcript of Slides History of Evolution Darwin Natural Selection Human Evolution Dr Chiu a One of Cuvier s most important contributions to science was the concept of extinction Here Cuvier is depicted examining a fish fossil A giant crater in Mexico indicates that 65 mya an enormous Slide 10 extraterrestrial object crashed on Earth Did the impact produce a catastrophe at the Cretaceous Tertiary K T boundary Slide 11 FIGURE 2 8b Georges Cuvier b In his 1796 paper on fossil and living elephants Cuvier suggested that mammoth remains represented a species different from any living elephant species and therefore mammoth remains were from a species that had gone extinct This idea was revolutionary because the common perception was that God had created all species none of which had ever gone extinct Slide 12 FIGURE 2 9a Carolus Linnaeus a Linnaeus a botanist zoologist and physician is known for his contributions to the system of classification used today by all biological scientists including physical anthropologists He is also thought of as one founder of modern ecology Slide 13 FIGURE 2 9b Carolus Linnaeus b Linnaeus s hierarchical scheme of nomenclature provided unique names for all varieties of plants and animals including those shown here Slide 14 FIGURE 2 11a Thomas Malthus a Malthus the founder of demography theorized that population size was limited by food supply Slide 15 FIGURE 2 11b Thomas Malthus b London s crowded conditions influenced Malthus s view that an insufficient food supply causes some people to fall into poverty while others are able to acquire the resources they need to thrive Slide 16 FIGURE 2 12a Jean Baptiste de Lamarck Transcript of Slides History of Evolution Darwin Natural Selection Human Evolution Dr Chiu a Lamarck developed an early theory of evolution involving the inheritance of acquired characteristics Although his mechanism of evolution was wrong Lamarck s recognition of the dynamic nature of life in the past made an important contribution to the development of evolutionary theory Slide 17 FIGURE 2 12 Jean Baptiste de Lamarck b According to the classic though incorrect example of Lamarckism giraffes stretched to reach food at the tops of trees their necks grew as a result and they passed on these long necks to their offspring Slide 18 FIGURE 2 14 Alfred Russel Wallace Although Darwin often gets sole credit for the development of the theory of evolution through natural selection Wallace here depicted ca 1860 contributed substantially to evolutionary theory Wallace was the leading authority on the geographic distribution of animals for example and was the first to recognize the concept of warning coloration in animals In addition he raised the issue of human impact on the environment a full century before it became a concern for the general public Slides 19 22 Charles Darwin and journey of the HMS Beagle Slides 23 26 Darwin s finches b f These islands are well known for their many endemic or native species such as the 13 species of Gal pagos finches also known as Darwin finches that are found only at this location Slide 27 FIGURE 2 3 Darwin Finches Darwin studied the physical variation in finches living on different islands of the Gal pagos Among other attributes he studied beak shape which varied from island to island Eventually Darwin related each beak shape to diet especially to the texture of food and how the food was acquired Finches with larger beaks typically consumed harder foods such as seeds and nuts while finches with smaller beaks ate softer foods such as berries Darwin concluded that each finch species had adapted to the particular environment and food resources of its island Slides 28 30 Natural selection text Transcript of Slides History of Evolution Darwin Natural Selection Human Evolution Dr Chiu Slide 31 This slide shows natural selection in action Following a drought which produces harder seeds beak depth increased This shows that beak depth is a genetically transmitted trait that responds in the predicted direction to natural selection Rosemary and Peter Grant have observed Darwin s finches for decades Natural selection acts on the phenotype which is an interplay between Slide 32 genetics and the environment Remember that environments shift over time traits that are advantageous in one environment may not be in another There is always variation in populations Slide 33 35 Different types of selection The example of beak depth increase is an example of directional selection We watched a short film clip about fence lizards and fire ants This slide Slide 36 attempts to illustrate that environments are constantly changing In the past and present for some fence lizard populations birds are the main predator The behavioral response determined by genetics to some extent is to stay very still and to have camouflage genetically determined In the present environment fire ants are a real threat Individuals who have the twitch response can run away and are likely to be more reproductively fit and pass this trait onto their offspring In the future we don t know how the environment will change but we do know it will