EEB 2245W 1st EditionExam # 2 Study Guide Exam type question:Which of the following is/are necessary for evolution by natural selection to occur?1. Environmental change False2. Variation among individuals True3. The best possible variant exists in the population False4. Variation among individuals is heritable True5. Different variants leave different numbers of offspring True6. What is best for the species is what is best for the individual FalseDefinitions and concepts:Adaptation: an adaptation is a characteristic that enhances the survival or reproduction of organism that bear it relative to alternative states. For a trait to be adaptive it is usually complex, designed for a certain purpose, and experiments should prove that it enhances survival or reproduction or performance.Altruistic trait: a feature that reduces the fitness of an individuals that bears it for the benefit of the population or species-cannot evolve by individual selectionAltruism: the reduction of the fitness of an individual for the benefit of the population or speciesAssortative mating: mating preference for phenotypically similar individualsDirectional selection: extreme form of natural selection where one phenotype is greatly preferredover another. Allele frequency shifts to the direction of that phenotype.Disassortative mating: mating preference for phenotypically different individualsDisruptive selection: type of selection where extreme values for a trait are preferred over intermediate values. Population is divided into 2 groups that are highly varied from each other.Evolution: is the change in the genotype (change in allele frequencies) of the populations over time leading to changes in their phenotype and behavior. Lecture notes:These 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.1977 drought-Severe drought- 2 mm (< 20% of normal rainfall)-Effect on adults was around 1200 finches and 180 finches (85% male)-Effect on fledglings: born in 1976 and 1 survived -Effect on reproduction: no fledglings -Drought favored one type of fish survival over the otherNatural selection in the wild:1- Environment isn’t constant: varies across space and time2- Any change in environment can change selection pressures3- As long as there’s heritable variation, population will respond to changes in environment: 1 evolve as a result of changesFisher’s Fundamental Theorem (Fisher was a statistician) The mean fitness of a population will increase (or remain constant) in every generationNatural selection increases fitness and increases adaptation Offspring are fitter than parents Directional A1A1 A1A2 A2A2Fitness 1 0.9 0.8Frequency 0.522: 5: 5 0.52P=0.5 0.25 0.5 0.25Mean fitness 1x0.25 + 0.9x0.5 + 0.8x0.25= 0.90.9 is the average (relative) survival probability of an individual in the populationActivity 81. Under disruptive selection, moves up whichever slope it’s on (selection short-sighted- no way of predicting what will happen)2. Under stabilizing selection still have homozygotes even though fitness is lowerFitness landscapes- genotypes (1 locus, 2 allele model) If there is a min/max then the selection is disruptive or stabilizing.Fitness landscapes- Phenotypes- Stabilizing selection- very common- Human birth rate is the trait. Mean phenotype in population has highest survival probability (=highest fitness)- Extreme phenotypes have lower probabilities of survival- Mean stays the same, variation changes- Disruptive selection- has a fitness minimum. Small and large beaks are in the same population. The beaks that were far from the mean survived better. Low survival for beak sizes close to the mean. - In the beaks case, it is an unusual outcome of disruptive selection. Big and small beakmating, offspring will have in between beak sizes; coupled with assortative mating (small beak male mates with small beak females; large beak male mates with large beak female).- Evolutionary consequence of disruptive selection: normal effect of disruptive mating selection. Evolution towards one peak (Fisher’s Fundamental Theorem) Directional Selection:Fitness advantage for individuals greater than the mean Genetic basis of traits(1 locus, 2 more alleles that explain the variation; multiple loci- height in humans: 180 loci affect variation in height. Mice: 6,000 loci).Consequences of multi locus genetic basis1. Continuous in traits2. Large number genotypes, but fewer phenotypes3. Same phenotype with different genetic basis4. Environment also contributes to variation 5. -A and D are strong selection.6. -Phenotype results from the interaction of genes and the environment.7. H2= Vg/Vp= varioation of genotype/variation of phenotype8. Genes are inherited, then through development from environment, the phenotype is obtained. The phenotype is not directly inherited. 9. Hight h2 means there is a strong resemblance between parents and offspring 10. Low h2 means there is a weaker resemblance11. -h2= 0 means there is no tendency for traits to be inherited12. -h2= 1 means there is no dependency on the environment, the trait is only dependent ongenes.13. -R= difference in mean phenotype (response to selection) of offspring from selected individuals vs. all individuals. 14. R/S is the slope: measure of how strongly offsprings resemble parents. This liets us predict how much evolution will occur. R/S= h215. Sexual selection: variation in traits that affect ability to set a mat. Or the quality of the mate. 16. Male-male competition is intrasexual selection17. Femal choice is intersexual selection (preferences to certain male traits)18. Widowbirds:19. -African grassland bird with around 17 species in genus20. -varying desires of traits for males. Glossy black plunage, bright feather patelos, tails of entire length. Male widowbirds establish territories, buld nest frames and then display. -Mitochondria and chloroplasts are inherited from egg/female line. This is good for the mitochondria gene but bad for other genes since they’re not being equally inherited. Mitochondria, unlike nuclear DNA, is not divided equally-Two sexes, with maternal transmission of organelles may have originated to eliminate this source of genomic conflict. Nuclear genes police the DNA. This is good for the mitochondria, not good for the individual. Males have great reproductive advantage in