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Unformatted text preview: ganism Equation : p 2 + 2pq + q 2 = 1 equency of homozygous dominant requency of het erozygous dominant equency of homozygous recessive ) Gamete Equation : p + q = 1 : frequency of dominant allele : frequency of recessive allele UN I T 1: EVOLUT ION Theories of Evolution: LAMARCK T HEORY: Three key points in Lamarck theory: 1) Need in environment that requires organism to change 2) Organism tries to change and over time causes a change in the organism during its lifetime 3) The acquired trait is passed onto offsprings. DARWIN WALLACE T HEORY: 1) Reduced Selection Pressure: Life is good: no predators, lots of food, ideal climate etc. 2) Increased Variation : Since life is good, more variations survive and increase in population 3) Reproduction Isolation: Varied organisms want to keep gene combination so no interbreeding. Develop methods of reproductive isolation: behavioral, temporal, ecological, mechanical and gamete. 4) Reuniting with general population: no interbreeding due to specialized mating 5) Competition: increased competition for food and resources 6) Increased Selection Pressure : Life is hard: more predators, competition for food 7) Selection: Survival of the fittest. MODERN T HEORY: Variation was genetic, due to gene and chromosomal differences which are inherited. Those with variations were selected by environment (natural selection) and their genotype frequencies increased in the population through differential reproduction. (survival of the fittest) Over time only organisms with that trait survive. 3 TENETS of EVOLUT ION: Overproduction: Every organism produces more offsprings than can survive. Competition: competition for food and space. Many die off and the more hardy survive. Survival of Fittest: Some better able to compete/survive to varied traits, these traits passed onto offspring. CAUSES OF VARIAT ION: Mutations: change of gene sequence caused spontaneously or induced my mutagenic agent Genetic Recombination: sexual reproduction Gene Flow: movement of new genes into a population Genetic D rift: Change in gene pool due to chance Founder Principle: The Isolated Smaller population has a different gene frequency than the larger population from which it came from. GRADUALISM AND PUNCTUATED EQU IL IBR I UM: Gradualism: evolutionary change is slow, gradual and continuous Punctuated Equilibrium: species have long periods of stability and then change as the result of geological or ecological change. CONVERGENT EVOLUT IO N : Placental mammals and marsupial mammals are very similar in appearance and function but are genetically different and are found in very different parts of the world. This is due to Convergent Evolution . Similar needs in the environment causes the ones with the most desirable traits to survive, and therefore being very similar to each other. This is an example of parallel evolution where similar environment selects similar traits....
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This note was uploaded on 02/05/2011 for the course PHYS 1010 taught by Professor Tomkirchner during the Spring '11 term at York University.
- Spring '11