BIOL 3040 test 2
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What is genetic variation?
Possessing different phenotypes within a population
What is environmental variation?
Environment that an organism lives in
What is genotype-by-environment interaction?
The way genotypes interact with environments
What does genetic variation, environmental variation, and genotype by environment interaction lead to?
Phenotypic variation: set of traits exhibited by an individual
What is an inducible defense?
- A phenotypic defense that can be expressed depending on the environment.
- Ex.) Daphnia pulex's armor growth in the presence of phantom midge kairomone
What is a reaction norm?
- the pattern of phenotypes that an individuals may develop under different environmental conditions
- One genotype does not necessarily give you one phenotype. The level of expression depends on other genotypes as well
What is phenotypic activity?
- different phenotypes in different environments
- caterpillars exposed to heat shock...
What is a synonymous mutation?
Base position change but no change in amino acids
What is a nonsynonymous mutation?
point mutation that results in an amino acid change
What is a nonsense mutation?
When a stop codon is coded for in a mutation
Besides mutation, where do new genes come from?
- unequal crossing over: an error in the genetic recombination that happens during meiosis
- Retrotransposition: When intronless RNA is reverse transcribed into dsDNA and it usually becomes a psuedogene
- Inversions: breakage of chromosomes and the reannealing of chromosomes
- Genome Duplication: plants becoming polyploidy
Order the following types of mutations from most frequent to least frequent: lethal, deleterious, neutral, beneficial
neutral, lethal, deleterious, beneficial
What are mutation accumulation lines, control lines, and recovery lines?
- benign (optimal)environemt propagated from a single individual at each generation
- propagated from Ig number of individuals and each generation
- start with single individual from mutation line, then propagate as control
What happens when the initial allele frequency is equal to the final allele frequency?
population is at genetic equalibrium
What is the Hardy-Weinberg equilibrium principle?
Allele frequencies are at equilibrium, no chande so no evolution. only if there is no selection, no mutation, no migration, no chance events, and mating is random
How does selection effect the alleles in the environment?
Certain phenotypes die off and allow for higher ratios of allele in the population.
How do new mutation frequencies change over time?
High initial frequencies and selection lead to increase in allele frequecies. High and low lead to lead to an equilibrium, and low and low lead to no frequencies
When is a population evolving?
Allele frequencies (p and q) will change over generation
What migration do we talk about in genetics?
What is random genetic drift?
Sampling error in the production of zygotes from a gene pool.
What is the founder effect?
The allele frequencies in the new population are likely, simply by chance, to be different from what they were in the source population.
How does genetic drift and selection affect populations?
smaller populations are affected more by genetic drift and larger populations are affected more by selection.
What is Kimura's neutral theory of molecular evolution?
most molecular evolution is a result of drift not natural selection. Deleterious mutations lost to natural selection. Some beneficial mutations are lost at low frequecies due to drift. Some are fixed via natural selections. Much more neutral mutations are fixed as a result of drift
What is coalescence?
The merging of genealogical as we trace allele copies backward in time
What is the most common form of nonrandom mating?
inbreeding: mating among genetic relatives
What is inbreeding depression?
Among the most important consequences of inbreeding for evolution. results from the exposure of deleterious recessive alleles
What are quantitative traits?
- Characters with continuously distributed phenotypes
- Determined by genotype and the environment
What is QTL mapping?
Using marker loci to scan chromosomes and find regions containing genes that contribute to quantitative traits.
What are the equations for broad-sense heritability and narrow-sense heritability?
(Genetic variation)/(Genetic Variation + Variation due to the environment)
(Additive genetic variation)/(Additive genetic variation + Dominance genetic variation + Variation Due to the environment)
How does one measure the strength of selection?
- measure survival and fitness
- Quantify trait of interest in those who survived + reproduced vs. those who did not
How can fitness be defined?
- number of offspring weaned
- number of seeds produced
- survival to age of breeding
How do you predict the response to selection?
Predicted response to selection = heritability times the selection differential
What is directional selection?
selection that favors one end of the spectrum and disfavors the other end of the spectrume
What is stablizing selection?
selection that favors the intermediate phenotype rather than the extremes
What is disruptive selection?
selection that favors both extreme phenotypes over the intermediate
How is genetic variation for fitness maintained?
- Most populations are not at equilibrium. Steady trickle of mutations lead to genetic variation in fitness related traits.
- Most populations balance beween deleterious mutations and selection for most QTLs, effect on trait is small, so selection on alleles will be weak which leads to genetic variation will persist
- Disruptive selection may be more common than recognized.
What is adaptation?
a trait or suite of traits, that increases the fitness of an individual compared withindividuals without the trait.
Why are differences among populations always adaptive?
- Traits can be fixed b/c of drift
- some of the traits are completely neutral
- not every trait is an adaptation
- adaptations aren't always perfect
What are the three way to find whether a trait is adaptive?
- Conduct an experiment
What is phenotypic plasticity?
individuals with the same genotype may have different phenotypes in different environments
What are the limits on adaptive evolution?
- functional constraints
- Lack of genetic variation.
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