* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Slides
Heritability of IQ wikipedia , lookup
Genetic testing wikipedia , lookup
Frameshift mutation wikipedia , lookup
Genome evolution wikipedia , lookup
Dominance (genetics) wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Public health genomics wikipedia , lookup
Gene expression programming wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Adaptive evolution in the human genome wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Point mutation wikipedia , lookup
Dual inheritance theory wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genetic engineering wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Genome (book) wikipedia , lookup
Designer baby wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Human genetic variation wikipedia , lookup
Koinophilia wikipedia , lookup
Genetic drift wikipedia , lookup
Evolution of Populations Lecture 2 Winter 2014 1 Darwin’s dilemma • How do organisms pass heritable traits to their offspring? 2 The Modern Synthesis 1844 - Darwin essay on Natural Selection 1859 – On the Origin of Species 1866 - Mendel published 1875 - Mitosis worked out 1890s - Meiosis worked out Early 1900’s - Chromosomal Theory of Inheritance 1953 – Structure of DNA discovered 3 Non-adaptive Evolution • Evolution: – a genetically based change in the characteristics of a population over time – a change in the frequency of alleles in a population over generations • Natural Selection Non-adaptive Evolution • Genetic Drift • Gene Flow • Mutation The Florida Manatee 4 5 Non-adaptive Evolution Genetic Drift • A change in a population's allele frequencies due to chance • Significant in small populations Fig. 23.9 6 Non-adaptive Evolution Genetic Drift: The Founder Effect Non-adaptive Evolution Genetic drift - The bottleneck effect – Sudden severe reduction in population size – Loss of alleles 7 Non-adaptive Evolution: Genetic Drift • Low mitochondrial DNA diversity 8 Non-adaptive Evolution: Genetic Drift • Loss of genetic variation makes population more vulnerable • Inbreeding depression • Increase frequency of harmful alleles Fig. 23.11 9 10 Non-adaptive Evolution: Genetic Drift Fig 23.11 Non-adaptive Evolution: Gene Flow Gene Flow • Transfer of alleles from one population to another • Reduces genetic differences between populations 13 Non-adaptive Evolution: Gene Flow Reproductively isolated populations 14 Non-adaptive Evolution: Gene Flow Gene Flow: Increases genetic diversity 15 Gene flow as a conservation tool 16 Non-adaptive Evolution Mutation • Random change in the nucleotide sequence of DNA • Ultimate source of new alleles 17 Mutations & Variation 18 19 Mutations & Variation • Review types of mutations (pgs. 344-346), alterations of chromosome structure (pgs. 298-300) and gene regulation (Ch. 18) Mechanisms of Microevolution • Genetic drift, gene flow and mutations & natural selection all lead to changes in variation within a population • Natural selection leads to adaptive evolution 20 The Hardy Weinberg Principle • How do we know whether a population is evolving? • Hardy-Weinberg equilibrium – Calculates the frequency of genotypes you would expect to find in a non-evolving population – frequencies of alleles and genotypes in a population will remain constant over generations, • unless acted upon by agents other than Mendelian segregation and recombination of alleles 21 22 Conditions for Hardy-Weinberg 1. 2. 3. 4. 5. Random mating No natural selection No genetic drift (large population size) No gene flow No mutation The Hardy Weinberg Principle • If the frequency of the alleles in a population are given by p + q = 1, • Then the frequency of genotypes will be given by p2 + 2pq + q2 = 1, p= frequency of one allele q = frequency of other allele • Hardy Weinberg Equation p2 + 2pq + q2 = 1 23 24 The Hardy Weinberg Principle • Gene pool – The total aggregate of genes in a population at a any one time (All of the alleles at all loci) • Population of wildflowers – 500 individuals • 320 reds • 160 pinks • 20 whites 25 Fig 23.8