Evolutionary Biology BIO 3350 Clemson
Evolutionary Biology BIO 3350 Clemson 12050 - BIOL 3350 - 001
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12050 - BIOL 3350 - 001
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This 4 page Class Notes was uploaded by Emily Emmons on Tuesday July 12, 2016. The Class Notes belongs to 12050 - BIOL 3350 - 001 at Clemson University taught by Dr. Michael Sears in Fall 2016. Since its upload, it has received 5 views. For similar materials see Evolutionary Biology in Biological Sciences at Clemson University.
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Date Created: 07/12/16
lecture 2 19:05 Chromosome inversions Inversions suppress crossing over, resulting in ‘super genes’ Linkage Are they important in evolution? Selection might favor chromosomal inversions to help maintain combinations of alleles across nearby loci Gene duplication Duplications of the entire genome are an important mechanism of speciation— particularly in plants Gene duplications as a mechanism of adaptation Changes in ploidy can alter phenotypes in a way that makes individuals better adapted to new environments Rates and Fitness Effects of Mutations Mutation accumulation experiments demonstrate that mutation rate evolves Gene duplication can be more common than mutations Mutation is a trait that can evolve Everyone is a mutant The distribution of fitness effects of new mutations: site-directed mutagenesis and accumulation Mutations come in 4 kinds: Lethal Deleterious Neutral Beneficial Lethal and deleterious mutations come The balance between mutation and natural selection It is the action of natural selection, culling damaging mutations and preserving the advantageous ones, that saves populations from inexorable decline. Population Genetics Integrates evolution by Darwinian evolution with Mendelian genetics From a population geneticist’s perspective, evolution can be defined as change across generations in the frequencies of alleles. The life cycle of an idealized population We want to know whether particular alleles or genotypes become more common or less common across generations, and why. Adults choose their mates at random. A numerical calculation Random mating in the gene pool produces zygotes in these proportions 100% The probability that we will witness the production of an A1A1 zygote is therefore P x P = p2 Hardy-Weinberg Eqn • Conclusion 1: The allele frequencies in a population will not change, generation after generation. • Conclusion 2: If the allele frequencies in a population are given by p and q, the genotype frequencies will be given by p , 2pq, and q .2 Why use it? No selection No mutation No migration No chance events Individuals choose mates at random The Hardy-Weinberg analysis identifies the mechanisms that can cause evolution in real populations 19:05 19:05