Evolution-Exam 2 questions and answers 100% guaranteed success.

Evolution-Exam 2 questions and answers 100% guaranteed success. genetic drift - correct es genetic variation results from random sampling faster rate in a small pop (alleles become fixed) genetic bottleneck - correct genetic drift by drastically reducing population size rare alleles are likely to be lost ie elephant seals founder effect - correct answers.a type of genetic drift random sampling founding a new population with very few individuals new population can differ greatly from source pop ex. organism moving from mainland to island (random allele) i.e. Huntington diesease brought to SA from Europe fitness - correct reproductive success of an individual with a particular phenotype components: survival to reproductive age, mating success, fecundity related to NS--not random compared to other individuals in pop relative fitness - correct ss of a genotype standardized by comparison to other genotypes a specific genotype fitness divided by average fitness of pop average excess of fitness - correct rence between average fitness of individuals with allele vs population average measure of how much more fitness a trait confers natural selection vs genetic drift - correct is weaker/NS stronger in large popilations small advantages in fitness can lead to large changes over long term adaptation - correct answers.a feature that enhances the fitness of a biological entity that possesses it relative to those that dont "anything that enhances fitness" negative selection - correct es that lowers fitness positive selection - correct es that increase fitness additive allele - correct s twice the phenotypic effect when two copiers are present at a give locus than occurs when only one copy is present not influenced by the presence of other alleles (no dominance) reach fixation in population directional selection - correct form is more favored than the other then shift to one direction or another variance = same mean = will go up or down depending what determines whether an allele becomes fixed in a population? - correct ance initial allele frequency selection coefficent selection coefficient - correct t by which the fitness of the genotype differs from the other genotype how is variation maintained? - correct flow mutation-selection balance balance selection conflicting selecting pressures gene flow - correct ent of alleles from one population to another decreases genetic distance between pops (makes populations more alike) magnitude depends on movement (physical features, characteristics of species i.e migratory birds) mutation-selection balance - correct of war between mutation and selection mutation is a random error that occurs, natural selection will act against negative alleles but not prevent negative alleles persist BECAUSE of mutation THROUGH natural selection balancing selection - correct tion favoring more than one allele maintains genetic diversity in a population by keeping alleles at frequencies higher than will chance or mutation alone heterozygote advantage negative frequency dependent selection heterozygote advantage - correct tion favors the heterozygote individuals over either the dominant homozygote or the recessive homozygote ie sickle cell anemia protects for malaria balanced polymorphisms (both alleles persist because of fitness of hetero) negative frequency dependent selection - correct genotypes have higher fitness than common genotypes maintains genetic variation within a population examples of how selecting pressures may conflict - correct ck feathers--trade of between reproduction and predation consequences of natural selection depends on: - correct ionship between genotype and phenotype (no evo occuring if phenotype isnt heritable) relationship between fitness and phenotype (features do not evolve by NS unless it affects reproduction or survival) limitations to natural selection - correct acts on existing variation pleiotropy (effects can be deleterious, beneficial or both) (selection acts on entire net effect) pleiotropy - correct e gene affects many phenotypic traits can be beneficial, deleterious or both selection acts on net effect human gene- fecundity and menopause antagonistic pleiotropy - correct ion with beneficial effects for one trait also cuses detrimental effects on the other trait i.e. Huntington Disease -- causes neuro to break down, also causes higher fecundity interbreeding - correct random mating does not alter allele frequency DOES alter genotype frequency Why does interbreeding make fewer heterozygotes? - correct ases chance of getting the exact copy of the alleles Why does interbreeding reduce fitness? - correct ed heterozygotes, also increases deleterious recessive alleles in homozygotes interbreeding depression - correct answers.a reduction in the average fitenss of inbred individuals relative to that out outbred individuals this arises because rare, recessive alleles become expressed in homo stat where they can detrimentally affect the performance of individuals interbreeding coefficient (F) - correct answers.(F) probability that two alleles at any locus in an individual will be identical because of common descent measure of how likely you have same allele because of common ancestor genetic distance (Fst) - correct answers.(Fst) measures the amount of population subdivision by comparing frequencies of heterozygotes a measure of inbreeding increases more rapidly in small populations uses neutral alleles (not under selection) Fst = (Ht-Hs) / Ht allele - correct of any number of alternative forms of the DNA sequence of the same locus allele frequency - correct answers. fixed allele - correct allele that remains in a pop when all of the alternative alleles have disappeared no genetic variation exists at fixed locus within a pop because all individuals are genetically identical at that locus epistasis - correct s when the effect of an allele at one genetic locus are modified by alleles at one or more other loci landscape genetics - correct answers.a relatively new field of research that combines population genetics, landscape ecology, and spatial stats mutation - correct change to the genomic sequence of an organism population genetics - correct study of the distribution of alleles within populations and the mechanism that can causes allele frequencies to change over time broad sense heritability (H2) - correct proportion of the total phenotypic variance of a trait that is attributable to genetic variance, where variance is represented in its entirety as a single value