* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Natural Selection Depends on Genetic Variation
Public health genomics wikipedia , lookup
Viral phylodynamics wikipedia , lookup
Genome (book) wikipedia , lookup
Adaptive evolution in the human genome wikipedia , lookup
Behavioural genetics wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genetic testing wikipedia , lookup
Genetic engineering wikipedia , lookup
Genetics and archaeogenetics of South Asia wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Dual inheritance theory wikipedia , lookup
Group selection wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Heritability of IQ wikipedia , lookup
Dominance (genetics) wikipedia , lookup
Human genetic variation wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Koinophilia wikipedia , lookup
Genetic drift wikipedia , lookup
Natural Selection EU 1.A: Change in the genetic makeup of a population over time is evolution Darwin’s Theory of Natural : ◦ There is variation within a population. ◦ Competition for limited resources results in differential survival. ◦ Individuals with more favorable phenotypes are more likely to survive and produce more offspring, thus passing traits to subsequent generations Natural Selection is a Major Mechanisms of Evolution Evolutionary Fitness Fitness = Reproductive Success Genetic Variation is essential for the survival of a species in a changing environment Sources of Variation ◦ Mutation ◦ Sexual Reproduction Segregation – Anaphase 1 Independent Assortment – Metaphase 1 Crossing Over – Prophase 1 Random Fertilization Natural Selection Depends on Genetic Variation Some phenotypic variations significantly increase or decrease fitness of the organism and the population ◦ Sickle Cell anemia ◦ DDT resistance in insects ◦ Antibiotic resistance in bacteria Favored Phenotypic Variation Environments can be more or less stable or fluctuating, and this affects evolutionary rate and direction; different genetic variations can be selected each generation. ◦ Peppered Moth Bernard Kettlewell vindicated by Michael Majerus 8 February 2012 as "Selective bird predation on the peppered moth: the last experiment of Michael Majerus.“ ◦ Global warming and flowering times in Thoreau's Concord: a community perspective. “Using a subset of 43 common species, we determined that plants are now flowering seven days earlier on average than they did in Thoreau's times.” Miller-Rushing & Primack, Ecology. 2008 Feb;89(2):332-41 http://www.ncbi.nlm.nih.gov/pubmed/18409423 Environmental Impact Genetic variation that is favored by selection & is manifested as a trait that provides an advantage to an organism in a particular environment Adaptation Evolution (especially in small populations) can be influenced by: ◦ Genetic drift – chance events causing changes in allele frequency Founder effect Bottleneck effect ◦ Mutations ◦ Human Impact Artificial selection Loss of genetic diversity Overuse of antibiotics Other Influences Conditions: ◦ ◦ ◦ ◦ ◦ Large population size Absence of migration No net mutations Random mating Absence of selection Rarely are these conditions met… Hardy-Weinberg Equilibrium Mathematical approach to calculate allele frequency, providing evidence for the occurrence of evolution in a population ◦ ◦ ◦ ◦ ◦ ◦ ◦ p+q=1 p2 + 2pq + q2 = 1 p = frequency of dominant allele q = frequency of recessive allele p2 = frequency of homozygous dominant 2pq = frequency of heterozygous q2 = frequency of homozygous recessive Hardy-Weinberg Equilibrium Example: A fruit fly population has a gene with two alleles A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg Equilibrium, what proportion of the flies carry both the A1 and the A1 alleles? ◦ What is given? p or q (this problem doesn’t tell you enough to know which for sure) ◦ What are you finding? 2pq (so it doesn’t matter if you are given p or q – the answer is still the same – 0.42) Hardy-Weinberg Equilibrium A second mathematical approach to calculate changes in allele frequency provides evidence for evolution. Graphical Analysis