BIO SCI 1010 1st Edition Lecture 15Outline of Last Lecture I. Staphylococcus AureusII. Stopping SuperbugsIII. AntibioticsIV. Acquiring ResistanceV. How Populations EvolveVI. Natural Selection Occurs in PatternsVII. Charles DarwinVIII. Most Scientists had a different view of lifeIX. By the 1800s New Views about Species and the History of Earth had emergedX. Darwin’s Influences and Experiences led him to his Theory of EvolutionXI. Darwin began an in-depth study of Change over Time (Evolution)XII. In the Origin of Species Darwin made two important pointsXIII. Populations produce more individuals than can surviveXIV. Competition was a factor for all living thingsXV. Darwin concluded that favorable variations will be naturally selectedXVI. Darwin concluded that natural selection can lead to evolutionXVII. Important points about evolutionOutline of Current Lecture I. Populations and Genetic DiversityII. Hardy-Weinberg equilibriumIII. Changes to the genetic makeup of a population can arise via two mechanismsIV. Why is genetic diversity important?Current LecturePopulations and Genetic Diversity• From a genetic perspective, each population of an organism has its own particular collection of allelesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• The total collection of alleles in a population is the population’s gene pool• Within the gene pool, each allele is present in a certain proportion, or allele frequency, relative to the total number of alleles• Compare the gene pool to one known not to be evolving in order to measure the genetichealth of populations -if the two populations differ, the population is evolving, and you can begin to investigate why • Allele frequencies in a non-evolving population: do not change over time• Genotype frequencies remain unchanged from one generation to the next, a condition known as Hardy- Weinberg equilibriumHardy-Weinberg equilibrium• Provides a baseline to judge if a population is evolving or not-for a gene with one dominant and one recessive allele • Five conditions must be met for a population to be in Hardy-Weinberg equilibrium1. No mutation introducing new alleles into the population-if a new allele arises THEN the allele frequencies will change2. No natural selection favoring some alleles over others -if a phenotype is more favorable than others THEN the allele frequencies will change 3. An infinitely large population size (and therefore no genetic drift)-the effect of small, isolated populations on genetic diversityo Small, isolated populations have less genetic diversity than larger populationso Limited genetic diversity impairs a population’s evolutionary success in the face of a changing environment o Genetic drift is a change in allele frequencies between generations that occurs purely by chanceo Randomly, some individuals just happen to survive and reproduce, whereas others do noto Genetic drift: example 1-the founder effect: a small number of individuals leave and establish a new population-newly established population may have lower genetic diversity than the original populationo Genetic drift: example 2-the bottleneck effect a population is suddenly reduced to a small number of individuals and alleles are lost from the population as a result o Genetic drift: the bottleneck effect -a population is cut down sharply and suddenly-often the remaining population will possess a greatly impoverished gene pool4. No influx pf alleles from neighboring populations (i.e., no gene flow)-gene flow between populations increases genetic diversity o Gene flow is the movement of alleles from one population to anothero Increases the genetic diversity of a local population by introducing alleles from its neighbors 5. Random mating of individuals • every individual has an equal likelihood of mating with another individual -sexual selection can lead to changes in a gene pool over successive generations-sexual selection is a form of natural selection that depends on an individual’s ability to obtain a mate-females may choose males for their traits-males may compete with each other for access to mates• no population can ever be in strict Hardy-Weinberg equilibrium-meet all 5 conditions-all natural populations are evolving-provides a baseline from which to measure evolution• evolution is a generation-to-generation change in the gene pool-taken over many generations, evolution can result in the gradual adaptation of species to the local environmentChanges to the genetic makeup of a population can arise via two mechanisms 1. mutations: random changes to DNA which can create new genes2. sexual recombination: during the formation of sperm and eggs, chromosomes can exchange pieces of DNA, shuffling genes Why is genetic diversity important?• Greater variation greater chance of survival• A diverse gene pool gives a population more flexibility to survive in a changing environment• The more genetically diverse a population is, the more ways it has to adapt • Nonadaptive evolution: is caused by mutation, genetic drive, and gene flow • Sometimes a change in allele frequency does not lead a population to become more adapted to its environment • Inbreeding is mating between closely related individuals• Inbreeding does not change the allele frequency within a population• It increases the proportion of homozygous individuals to