Unit 3 Study Guide Lecture 19 Evolution Intro Section 22 2 Concepts Understand the difference between natural selection and evolution Understand the basic principles of natural selection Be able to distinguish between evolutionary change and other kinds of changes Understand that evolution produces allele frequency changes inherited phenotypic changes differences among populations new phenotypes and new species and phylogenetic relationships Natural selection the process by which organisms with characteristics that are better suited for their current environment will produce more offspring than those without said characteristics over time there will be an increase in the amount of organisms with these better suited characteristics Evolution may be thought of as descent with modification the concept that Earth s many species are descendants of ancestral species that were different from present day species Evolution is something that happens in populations not individuals Changes the genetic nature of populations by increasing the frequency of a specific allele or group of alleles whichever ones are being selected for Does not CREATE new genes only mutations cause random changes in DNA that may cause modification of an existing gene Can lead to changes in the mean phenotype of populations Can lead to the differentiation of populations Can lead to the formation of new species Results in branching pattern of change over time Italian Wall Lizard Introduced from Kopiste Island to Mrcaru Island in 1971 5 lizards Habitat is different Diet is different Mrcaru lizards eat much more plant material Mrcaru lizards have larger heads with more powerful jaws Also have a modified digestive system with an entirely new structure cecal valve 30 years later the 2 populations were compared and the Italian wall lizards had modified their heads and digestive system to match that of Mrcaru lizards 30 years is considerably short for evolution to occur evolution can occur quickly Requirements for Natural Selection 1 Overproduction of offspring more offspring are produced than can survive 2 Genetic variation differences in the genetic code between organisms within a population must be present so that nature can select certain genes phenotypes over others 3 Struggle to Survive some organisms are better adapted to the environment and 4 Reproductive Success Fitness organisms with better suited genes will pass survive while others die on these genes to their offspring Natural selection is the process that drives evolution evolution could not occur without natural selection Due to natural selection slight changes can be observed from generation to generation of a certain population over a very large period of time the species that originally inhabited the environment will be different from the one or several there now Lecture 20 Introduction to Evolution Ch 22 Concepts Know that Darwin came up with his ideas after voyage on the Beagle Galapagos animals were influential Know that Wallace independently came up with same idea Understand the five ideas in Darwin s theory Understand that exposure to the diversity of life around the world was an important influence Understand the basic process of natural selection Understand that evolution can be depicted as a branching tree Terms evolution natural selection fitness adaptation phylogeny 1 Evolution descent with modification the idea that living species are descendants of ancestral species that were different from the present day ones the change in the genetic composition of a population from generation to generation 2 Natural selection a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits over time there will be an increase in organisms with these traits 3 Fitness a measure of one s reproductive success how many offspring one has average contribution to the gene pool of the next generation made by an individual of a certain genotype or phenotype 4 Adaptation inherited characteristic of an organism that enhances its survival and reproduction fitness in a specific environment 5 Phylogeny the evolutionary history of a species or group of organisms may be used to show evolutionary relationships between 2 or more organisms Importance of Evolution 1 Explanation for the Diversity of Life 2 Framework for understanding differences and similarities 3 Helps Integrate Different Areas of Biology 4 Explains otherwise inexplicable aspects of biology Darwin Other Contributors Darwin s exposure to large diversity of animals and plants around the world had huge influence on his theories of evolution and natural selection He experienced an earthquake and observed how it had caused rock along the coast to be thrust upward concluded that fossils in the Andes mountains must have been raised there by earthquakes as well The Galapagos islands in particular had a large impact on Darwin found several species of mockingbirds that differed from island to island and differed from any species in South America although they were similar hypothesized that the islands had been colonized by organisms from south America and over time exposure to different environments lead to differences in the species natural selection Historical Background time Charles Darwin 1809 1882 began work as a Biologist in the 1830s At that Belief in special creation and a young earth However among geologists and natural historians it was apparent that the evidence Biblical literalism was widespread in European culture did not support this model Several earlier proponents of evolution e g Larmarck and Erasmus Darwin Lamarck Early 19th century Proposed first comprehensive idea of evolution Inheritance of acquired characteristics physiological changes made in an organism s lifetime can be passed on to its offspring For example Lamarck thought that a giraffe s long neck was the result of one giraffe stretching its neck throughout its life and passing that stretched neck to its offspring who would stretch its neck even more and pass that onto its offspring theory was not correct Charles and Lyell provided most compelling evidence sedimentary geology Lyell developed idea of uniformitarianism mechanisms of change are constant over time Alfred Russel Wallace spent a total of 14 years in the Amazon and Southeast Asia Came up with evolutionary ideas that were very similar to Darwin s sent Darwin his paper for evaluation a joint
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