Flashcards
Population Genetics
Cards in this deck (69)
- 1Why do we study genes in populations?Gene frequency/population size affects the fitness of individuals
- 2What are population genetics?The body of Mathematical principles that explain how genetic variation changes in populations over space and time.
- 3What are the two attributes of a population?Gene frequency
Gene pool - 4What is gene frequency?The proportion of an allele in a population
- 5What is gene pool?The sum of all the alleles in a population with the potential to contribute to the next generation.
- 6What is the result of interbreeding?Heterozygotes disappear from a population and the proportion of homozygotes increases
- 7What is the effect of migration on heterozygote numbers?Migration increases the proportion of heterozygotes in a population.
- 8How do you calculate allele frequency when there are two alleles at a locus?Frequency of homozygotes + 1/2 (frequency of heterozygotes)
- 9What did Hardy and Weinburg prove?Allele frequencies do not depend on dominance/recessiveness but remain unchanged from generation to generation.
- 10What does the Hardy-Weinburg Principle show?It explain why recessive genes don't disappear over time in a population. At equilibrium, both gene and genotype frequencies remain constant from generation to generation. It is the gene frequencies of the parent population that determine the genotypes of the next generation.
- 11What are the Hardy-Weinburg equations?p2 +2pq + q2 = 1
Where:
p2 = frequency of the dominant homozygote
2pq = frequency of heterozygote
q2 = frequency of recessive homozygote
p + q = 1
Where:
p = frequency of dominant allele
q = frequency of recessive allele - 12What are the assumptions of the Hardy Weinburg Principle?1. Large population >10 000
2. No mutations
3. No migration
4. No selection
5. Random reproduction - 13How do you calculate the number of individuals in a population with a specific genotype?Multiply the genotype frequency by the total population size
- 14What type of allele do people with blood type O have?Double recessives
- 15What are rare recessives?The 'carrier' heterozygotes are present at high frequencies e.g. albinism
- 16What causes changes in gene frequencies?1. Natural selection - alters reproductive success
2. Mutation - alters DNA sequence
3. Migration - gain/loss of individuals that make up the genome
4. Genetic drift - fluctuation in gene frequencies due to small population size - 17Why do deleterious alleles remain?1. Late onset - no effect on reproductive success e.g. Huntingtons
2. High mutation rates e.g. Duchenne muscular dystrophy
3. Heterozygote advantage e.g. CF - 18What are the applications of population genetics?1. Deviations from HW principle
2. DNA fingerprinting
3. Genetic counselling - 19What is a theory?A hypothesis that has been verified/supported by facts
- 20What is consilience?Different sources of evidence agree with one another
- 21What is temporal change?Change over time by which organisms come to differ permanently from their ancestors with respect to any heritable traits/characteristics
- 22What does Heritable mean?Characteristics passed on/transmitted from parents to offspring
- 23What is Anagenesis?Change within a single lineage.
Usually the ancestral form disappears as the entire species changes to a new form (transformation). - 24What is Cladogenesis?Division of a single lineage due to genetic divergence (splitting/branching)
- 25What does a division event result in?Two new lineages or just one new lineage in addition to the original.
- 26What is phylogenetics?The study/reconstruction of phylogenies
- 27What is Microevolution?Evolution at the population level i.e. within-species evolution (intra-specific evolution).
- 28What is speciation?Formation of a new species. Occurs mainly through cladogenesis.
- 29What is Macroevolution?Evolution at the species level and above i.e inter-specific evolution which involves splitting of lineages and divergence of species and higher taxa
- 30What are Characters?Any measurable item of an organism e.g. height
- 31What is Character State?Alternative variants of a character e.g. eye colour
- 32What is the genotype?The information stored in all of the genes of one individual/ the combination of alleles at one or more studied loci in one individual.
- 33What are Kinetoplasts?A mass of mitochondrial DNA lying close to the nucleus in some flagellate protozoa
- 34What examples of 'junk DNA' proved some of it is functional?miRNAs - micro small non-coding RNA
snRNAs - small nuclear RNA involved in splicing - 35Why is true junk DNA useful to evolutionary biologists?It is assumed to not be subject to natural selection
- 36How does a single nucleotide polymorphism affect a nucleotide base sequence?1. They are termed different alleles of the same gene
2. The locus is said to be polymorphic
3. There can be many more than two alleles - 37What is the Phenotype?The observable characteristics of an organism
- 38Give an example of an extended phenotype?Nests
- 39What non-genetic factors can give rise to variation?Wear/trauma
Disease
Somatic mutation - 40What was the effect of cloning potatoes of just one variety?The population was not genetically diverse therefore P. infestans caused a famine.
- 41How was the problem of Black Sigatoka disease in plants made worse?Only a few varieties of banana were cultivated
These varieties were cloned
Genetic variability of fungus allowed it to evolve resistance to fungicidal chemicals. - 42What are Continuous Traits?Intermediates exist between two extremes.
Often represented by a line graph.
Many gene loci involved with small effect.
Many alleles involved.
Harder to discern the contribution of the individual alleles to the phenotype.
Environment often plays a role.
Examples are height, milk yield. - 43What are Discontinuous Traits?No intermediates exist.
Often represented by a bar chart.
One or a few gene loci involved with major effect.
Usually only a few alleles involved.
'Allele-for-trait' effect clearly evident in the phenotype.
Environment has little effect.
Examples include eye colour, ear lobe attachment. - 44How is continuous variation examined?Take a measurements from a large and representative sample
- 45How is discontinuous variation examined?Scoring
- 46What statistical test can be done to compare the mean and variance between samples?T-test
- 47What is the order of most common to most rare types of mutation?Most common: Point substitution
Microdeletion
Microinsertion
Mobile element insertion
Inversion - 48What processes introduce genetic variation?Mutation
Recombination - 49What processes remove genetic variation?Genetic drift
Natural/Artificial selection - 50What is genetic drift?Random changes in allele frequencies due to a small population size. Causes a loss of heterozygosity and increase in homozygosity.
- 51What is genetic bottleneck?Random reduction in the number of breeders
- 52What is inbreeding?Mating between relatives
- 53What is Linkage Disequilibrium?Non-random association between loci. Shows a linear correlation on a graph.
- 54What is Linkage Equilibrium?Random association between loci.
Shows a horizontal line on a graph. - 55What is adaptive evolutionary change?Under natural conditions, the genetic variant conferring higher fitness increases in relative abundance within the gene pool.
- 56How does an insecticide-resistant insect evolve under insecticide-free conditions?1. Variant has a shorter average life span
2. Leaves fewer progeny
3. Variant is less fit so is rare throughout generations
4. Variant is more likely to become extinct - 57How does an insecticide-resistant insect evolve under insecticide application?1. Non-resistant individuals die and are less fit than variant
2. Variant has a longer life span
3. Variant leaves more progeny
4. Proportion of variant increases within the next generation
5. Variant has a selective advantage - 58What are everyday examples of adaptive evolutionary change?Insecticide resistance in head lice
Warfarin resistance in rats
Antibiotic resistance in bacteria - 59What is Artificial Selection?Mimics natural selection in terms of causing adaptive evolution however the breeder decides which trait has the highest fitness. It is correlated with a higher reproductive rate.
- 60What are selectively neutral genes?Neither adaptive nor maladaptive.
They are not influenced by natural selection.
Undirected (random) evolutionary change.
Neutral genes known to 'hitch-hike' with genes that have an adaptive function could be subject to selection.
Some are expressed in the phenotype and others aren't.
Examples include: markings on clover leaves, markings on cone shells. - 61What is the function of adaptive genes?Have either a positive or deleterious effect on fitness.
- 62What is Pleiotropy?Multiple phenotypic effects of an individual gene.
- 63What is antagonistic pleiotropy?In males, testosterone can give increased fitness in early life but can lead to prostate disorders in later life.
In females, pregnancy and lactation decreases bone mineral density and causes osteoporosis later in life but gives higher fitness in early life. - 64What is phenotypic plasticity?The phenotypic expression of the genotype is often environmentally determined.
- 65What constraints are there upon evolutionary change?1. Insufficient genetic variation in the gene pool
2. No selection pressures
3. Sufficient selection pressures but there are constraints on changing the 'design'. - 66Give examples of design constraints in insects that suggest why they will never be large.1. Terrestrial animals need to shed their exoskeleton and if their bodies were very large, their bodies would collapse under their own weight at the shed.
2. A system of air-carrying tubes would not be efficient in insects if the maximum body size were much greater than it is. - 67Give examples of brief phases of un'adaptedness.1. In a population colonising a new habitat e.g. genetic drift
2. If the habitat changes rapidly - 68What is the Red Queen hypothesis?Organisms must constantly adapt not to gain reproductive advantage but to survive in an ever-changing world.
- 69What is the Teleological view?Religions and philosophies teach that there is a purpose and that humans are its intended end product.
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- Undergraduate Genetics and Evolution Flashcards on Population Genetics, created by Olivia Hearn on 11/05/2019.
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- Olivia Hearn · May 2019
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- May 11, 2019
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