The history of evolutionary thought 01 25 2016 Evolution change through time What is evolution What evolves In biology Evolution is the change in a population s allele frequency from one generation to the next Why is the theory of evolution important in biology Evolution unites all aspects of biology and all living organisms into a comprehensive and coherent body of knowledge What is a scientific theory o It is not an idea or hypothesis o Is based on large amounts og info assembled as a unified explanation o Provides an explanation for observed phenomenon Previous ideas about nature The middle ages in Europe o Stasis All aspets of nature are fixed and unchanging The idea of stasis was shaped by o The rigid class system of feudal societies o The literal interpretation of Christianity o The scientific revolution The discovery of the new world The new world contained unknown plant and animal species Circumnavigation of the globe The earth was not flat Copernicus and Galileo The earth revolved around the sun Keppler Descartes and Newton Laws of physics etc The path to natural selection Carolus Linnaeus o Binomial nomenclature Georges Cuvier o Introduced the concept of extinction to explain the disappearance of fossil animals o Proposed a catastrophic events Charles Lyell o Argued fr the theory of uniformitarianism Geological processes observed in the present are the same that occurred in the past For such slow acting forces to produce momentous change the earth must be older than suspected The concept of deep time Utah s Bryce canyon Thomas Malthus o Pointed out that pop Size increases exponentially while food supplies are relatively stable o Organisms have a constant competition for food and other resources Overcrowding and poverty in London Jean Baptiste Lamarck o Attempted to explain evolution o The theory of the inheritance of acquired characteristics Physical changes in an organism Giraffe s originally having long necks after a period of time Charles Darwin o Studied medicine for 2 years Became acquainted with the evolutionary ideas of o Sailed across the world for 5 years Lamarck HMS beagle Darwin believed in the fixity of species at the beginning of the 5 year voyage but he had doubts Galapagos Islands Each island has different habitats due to different elevations on the islands Birds on the Galapagos o Beaks of birds important for food intake insects Narrow beaks nectar pollen Darwin collected 13 diff variests of Galapagos finches o Varieties shared many structural similarities but differed in their shape and size of their beaks o Darwin recognized that the various finches had all descended from a common mainland ancestor and were modified in response to different island habitats Darwin returned back to England o Began to develop his views on what he termed natural selection He borrowed this concept from animal breeders who select breeding animals that exhibit specific traits Darwin s synthesis During the late 1830s Darwin recognized Favorable variation would tend to be preserved and unfavorable ones destroyed The result of this would be the formation of new species Alfred Russel Wallace Joined an expedition to the Amazon in 1848 collecting plants and animals Wallace Darwin Presented their ideas at Linnean Society of London got no recognition Darwin published a book and got mixed views due to it being controversial Constraints on the 19th century Evolutionary thought Blending Inheritance Rationale for blending inheritance o Blend of your parents Plant and animal breeders successfully combined traits from two breeding stocks Mendel Provided a mechanism for inheritance Published his work on breeding peas in 1865 Most of science was unaware of his work at the Key terms Allele form of a gene time Genotype genetic makeup of a trait Phenotype the appearance of a trait what can be observed Homozygous the same Heterozygous different Particulate theory of inheritance Accounts for no loss of variability No blending of characteristics Continuing maintenance of characteristics Recombination of genes actually generates new genotypes phenotypes Cytogenetics Modern synthesis Theodore Dobzhanksy o United the genetics of variation with the discreteness of o The speciation process could be studied wit experimental species genetics o Coined the term isolation mechanisms o Genetics and the origins of species 1937 Ernst Mayr o Unified systematics and evolutionary theory o Biological species concept Geographical speciation model o Systematics and the origins of species 1942 George Gaylord Simpson o Integrated paleontology with genetics and evolution o Reinforced Dobz View that genetics was sufficient to account for micro and macroevolution Discovering the structure of DNA of DNA double helix structure The modern synthesis Watson Crick awarded nobel peace prize in 1953 for discovery Synthesis of biology Bridged the gap between experimental geneticists and naturalists All evolutionary phenomena can be explained in a way consistent with known genetic mechanisms Evolution is usually gradual Gradualism does not mean constant rate of change Selection is the main mechanism of change Modern misconceptions about evolution Many biologists don t believe in evolution o False not occur There are gaps in the fossil record this shows that evolution does o Gaps in the fossil record are expected to occur and do so for natural reasons There are no missing links i e transitional fossils this shows that evolution does not occur o False countless transitional fossils We evolved from chimpanzees o No share a common ancestor with chimpanzees You can t believe in evolution if you believe in God o Evolution is not meant to explain the creation of life and the universe o Explains how life changes and diversity within certain species o Religion is faith based Belief that does not rest on logical proof or material evidence 01 25 2016 01 25 2016