Bio 1306 Week 1 Notes
Bio 1306 Week 1 Notes Bio 1306
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GEOL 1313 - 002
Diana Hernandez Vega
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This 3 page Class Notes was uploaded by Kimberly Rodriguez on Wednesday January 20, 2016. The Class Notes belongs to Bio 1306 at University of Texas at El Paso taught by in Spring 2016. Since its upload, it has received 162 views. For similar materials see Organismal Biology in Science at University of Texas at El Paso.
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Date Created: 01/20/16
Organismal Biology Dr. Carl S. Liebe Week 1 1/20/2016-1/28/2016 Chapter 15: Processes of Evolution Evolution The change in genetic makeup of populations over time Evolutionary Theory The application of the process of evolution to questions in biology Population Community of organisms in a specific time and place Species Group of organisms composed of similar individuals 2 Questions 1) Why are organisms so well adapted to where they live? 2) Why are there so many species of organisms? Lamarck (1800) Presented evidence for evolution but his explanation of how it occurred was flawed. Darwin’s Propositions 1) Species change over time 2) Descent with modification- divergent species separate over time and have a common ancestor 3) Natural selection- the survival and reproduction of individuals depends on their traits On the Origin of Species Written by Darwin. Provided evidence of natural selection as a mechanism for evolution. Darwin’s observations 1) All individuals in a population show variation. 2) Populations are usually stable. 3) More offspring tend to be created than those that survive. His conclusions 1) The environment picks individuals that are fittest to survive. 2) Those variations that allow the individuals to be fit to survive are somehow passed down to generations. Mendel (1900) Discovered the basic principles of inheritance using pea plants Hugo de Vries Studied mutations and stated that theyare a major evolutionary force. Felt Darwin was wrong in stating natural selection was the main evolutionary force. Thomas Hunt Morgan 1908- established Drosophila lab. He worked with fruit flies and was able to clarify the role of chromosomes in inheritance. Synthetic Theory (1930) Combined Mendelian principles with Darwin’s evolution. Three rules: 1) Mutation creates variation and not natural selection by itself. 2) It is beneficial for a population to have great variability. 3) There is no goal in evolution. Microevolutionary Change in gene and allele level Gene Sequence of DNA that does something Allele Different form of a gene caused by mutations Mutation Change in the nucleotide sequence; produces a different allele. All mutations help restore genetic variation. Mutation rate Very low: 10 or 10 changes per base pair The sum of all copies of all alleles in a population or the sum Gene Pool of genetic variation in a population Allele Frequency Proportion of each allele in the gene pool Genotype Frequency Proportion of each genotype among individuals Allele variation/ population *The more individuals, the greater the # of alleles present. size *Themoreindividuals,thegreater#ofgenotypiccombinations therefore greater genotypic variation. *In a large population there are only a few alleles per gene presentbecauseallelesarecausedbymutationswhichareslow. 1) Increase in the allele frequency for the selected favored Selection for alleles allele over time expressed in the phenotype leads to: 2) Increase in genotypic frequencies for genotypes that contain the favored allele 3) Increase in phenotypic frequencies that are the result of the expression of the genotype containing the favored allele 4) Decrease in allele frequencies for disfavored alleles 5) Decrease in genotype/phenotype of disfavored alleles Artificial Selection Breeding of plants/animals to produce desirable traits. Natural selection is the process in nature analogous to artificial selection. Selection of favorable alleles increases the individuals’ fitness. Darwin’s Fitness Increased ability of surviving and reproducing Modern Fitness Individuals that contribute their alleles by reproducing more have better fitness than those that reproduce less Adaptation Favored trait that evolves through natural selection Gene Flow Movement of individuals and gametes between populations that change allele frequencies within the population. Genetic Drift Random changes in allele frequencies from a generation to the next Population Bottleneck Events that cause only a small # of individuals to survive The Founder Effect Because of size, the small # of individuals that remain most likely don’t possess all of the alleles that used to be present in the gene pool of the original population.
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