Chapter 22 Study Guide Evolution a gradual change over time in the genetic composition of a population responsible for biological diversity amongst organisms Natural selection the process by which characteristics of a population change over many generations as organisms with heritable traits survive and reproduce passing these traits to offspring Evolutionary adaptation alterations of a species in order to better improve their ability to survive and reproduce in relationship to the environment Natural theology a once commonly held view that adaptations amongst organisms were evidence that a higher creator had designed each species for a purpose Fossils remains or traces of organisms from the past mineralized in sedimentary rocks Sedimentary rocks rocks that have formed due to the deposition and solidification of sediment typically a result of mud and sand settle to the bottom of seas lakes and marshes Paleontology the study of fossils largely developed through the work of Cuvier Gradualism the idea that profound geological changes take place through cumulative slow and continuous processes on Earth Uniformitarianism the idea that geological processes remain unchanged throughout Earth s history Descent with modification a theory proposed by Darwin suggesting that all organisms are related through descent from a common ancestor of the remote past over time these descendents have accumulated diverse modifications or adaptations that allow them to survive and reproduce in specific habitats Artificial selection selective pressure exerted by humans on populations in order to improve or modify particular desirable traits selection of individuals with certain traits to breed more of such Biogeography the geographical distribution of species Homology similarity in characteristic traits from common ancestry Homologous structures structures in different species inherited from a common ancestor Vestigial organs structures that have marginal if any importance to a living organism but which had important functions in the organism s ancestors Ontogeny the development and growth of the individual Phylogeny the origin and evolution of lineages Chapter 22 Study Guide 1 Darwin s publication of the Origin of Species established a cohesive connection amongst different forms of life something that before was believed to be unrelated In his book he emphasized two principal ideas the first being that present day organisms descended from different ancestral species and the second that natural selection served as the primary mechanism for evolutionary change 2 Plato s philosophy of idealism essentially held that there were two coexisting worlds one ideal and eternal and the other fantasized and imperfect He theorized that ideas were what encapsulated the essential nature of things rather than the physical form humans could sense Greek philosopher Aristotle opposed the concepts of evolution and rather believed that species were unchanging He hypothesized that all living forms could be arranged on a ladder of increasing complexity the scala naturae and each of these species could fall perfectly in line amongst this scale In an overall sense Plato s philosophy looked at life in a far more abstract way than Aristotle s which was rather empirical 3 Linnaeus studied as a physician and botanist and is credited for founding the binomial system of classifying organisms according to genus and species Similar species were divided into increasingly more general categories though he did not believe that similarity between species was an implication of evolution His system of taxonomy was incredibly influential in the development of Darwin s research as Darwin developed his hypothesis on the idea that organisms may be related through a common ancestor due to their similarities 4 Cuvier played a large role in developing paleontology the study of fossils He recognized that extinction was a common occurrence throughout life and from this he advocated the theory of catastrophism He worked to examine rock strata in the Paris Basin and noted that older strata was far more different than the newer fossils As well as this he scientifically documents fossils in the Rockpile and noted similar conclusions with strata This allowed him to develop the concept that boundaries between strata were a result of local floods droughts or other sudden catastrophes that destroyed past species In general Cuvier utilized his work with fossils to support new and radical ideas regarding extinction 5 Cuvier asserted that sudden catastrophes were what defined strata and also concluded that different organisms in strata were not a result of evolution but migration 6 Geologist Hutton proposed an opposing theory to Cuvier s catastrophism and instead suggested that geological processes took place through cumulative slow and continuous processes on Earth Thus valleys were formed by rivers flowing through rocks and sedimentary rocks were formed from soil particles that eroded from land and were carried by rivers to the sea A period of time later Charles Lyell proposed a theory of uniformitarianism suggesting that the geological processes on Earth had not changed throughout time If geologic changes were the result of slow processes rather than sudden events Lyell realized that the Earth must be far older than once expected Darwin considered both Hutton and Lyell s theories when developing his own and Chapter 22 Study Guide realized that the subtle processes of the Earth were also able to act on living organisms serving as a gradual evolution over time 7 Jean Baptise de Lamarck published his own theory on evolution based on his observations of fossil invertebrates at the Natural History Museum of Paris in the late 1700s Through his comparisons of fossil records and current species Lamarck discovered what he referred to as a line of descent in which fossils developed chronologically into the modern species of the day Through this observation he developed a two principle model which highlighted the ideas of use disuse and inheritance of acquired characteristics Through use and disuse different mechanisms of the body used extensively become stronger and more necessary over time while those not necessary for the environment gradually deteriorate leading to the idea of vestigial structures He also elaborated on acquired characteristics meaning that modifications to an organism could be passed down to their offspring something that influenced Darwin s
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