Lecture 20- Population Genetics Flashcards
True or false: Phenotypes are either represented or not represented. There is no in between.
False; phenotypes often occur in a gradient (contrary to Mendelian genetics)
What are the two ways in which a population can end up very small?
The bottleneck effect and the founder effect
True or False: Rapid asexual reproduction often has frequent mutations
True
What is consanguineous mating?
Mating between individuals who are closely related
What does p represent in the Hardy-Weinberg equation?
Dominant homozygous frequency
What is gene flow and what does it result in?
Movement of genetic information (alleles) between populations (tends to reduce the differences between populations over time)
What is a fixed allele?
A fixed allele is an allele that is the only variant that exists for that gene in all the population (a fixed allele is homozygous for all members of the population)
What does q represent in the Hardy-Weinberg equation?
Recessive homozygous frequency
True or False: The recombination of chromosomes that occurs during sexual reproduction leads to new alleles
False; the only source of new alleles are mutations
What is the founder effect?
The loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population (limits number of alleles in the next generation)
What is stabilizing selection?
Type of natural selection in which the population means stabilizes on a particular non-extreme trait (occurs when the extremes of a trait are selected against)
What does pq represent in the Hardy-Weinberg equation?
Heterozygous frequency
What is a gene pool?
All alleles of all genes in a population
What is non-random mating?
Occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of individuals (some choice/preference)
What is allele frequency?
Relative proportion of a specific allele in a population
True or False: Hardy-Weinberg equilibrium describes a population that is evolving
False; the Hardy-Weinberg equilibrium describes a population that is not evolving
What is directional selection?
Mode of natural selection in which a phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype
What is a silent mutation?
Change in DNA sequence without a subsequent change in the amino acid or function of the protein
What is the difference between the two Hardy-Weinberg formulae?
One formula yields the frequency of organisms (individuals) in a population whereas the shorter formula yields the frequency of alleles
What is random mating?
Describes a situation in which all individuals of one sec are equally potential partners of all members of the opposite sex (mate choice has nothing to do with genotype)
What is disruptive selection?
Type of natural selection that selects against the average individual in a population. This population would show phenotypes if both extremes but have very few individuals in the middle
What is genetic drift?
Variation in the relative frequency of different genotypes in a small population (alleles are lost/ random events can dictate who survives/reproduces)
What is the bottleneck effect?
Sharp reduction in the size of a population due to environmental effects (catastrophic event can lead to few survivors and subsequently limits the number of alleles in the next generation)
What effect would the lack of gene flow have on population?
No gene flow (isolated populations)-> accumulation of differences between populations
True or False: Allele frequencies in a gene pool tend to stay constant until altered by an outside force
True
What are the differences between microevolution and macroevolution?
Microevolution refers to the shift of allele frequencies over generations (small gradual changes), whereas macroevolution results in changes significant enough to transcend the boundaries of a single species (taxonomic group)
