BIO 1M03 Test 1 Questions With Correct Answers

Criteria for natural selection - Answer variation, heritable, influences fitness natural selection acts on __________ and evolutionary change acts on _____________ - Answer individuals, populations Artificial selection - Answer driven by humans selectively breeding How fast/far can artificial selection go? - Answer FAST -depends on how many genes -how much the phenotype is controlled by the environment FAR -presence of deleterious trade offs -limits of the genetic variation available Non-tree like parts of the tree of life - Answer -hybridization -lateralization -sex -endosymbiosis Why do giraffes have long necks? - Answer -not for eating off high trees because they forage lower to the ground -long necked males win more fights than short necked males so they produce more offspring and pass on the gene Naked mole rats - Answer -eusocial and fossorial -highly inbred -community latrine Darwin and Wallace - Answer -changes in species over time is due to natural selection acting on heritable variation -evolution is decent with modification (species change through time and are related by common ancestry) Evidence for change through time - Answer -fossils -extinction -ancient DNA -transitional forms -vestigial traits -artificial selection -speciation Geographic continuity - Answer -extinct fossil species are generally succeeded by similar species in the same geographic region (ancestors and descendants) Geographic relationships - Answer -galapagos mockingbirds are more related to each other than species from the mainland -monkeys on Sulawesi have strong geographic structure Vestigial trait - Answer -lost their ancestral function but still remain -human coccyx, appendix, mole rat eyes, whale foot bones, snake hip spurs Homology - Answer similarity that exists in a species that was inherited from an ancestor Genetic homology - Answer -similarity among species in genetic aspects that is due to shared ancestry -storage of genetic info in DNA -plasma membrane -transcription and translation -ribosomes and ATP -chimps and humans differ by only 1.5% of nucleotides -eyeless and aniridia genes determine where eyes develop in fruit flies and humans Developmental homology - Answer similarity among species in embryonic development that is due to shared ancestry (humans, cats, chickens) Structural homology - Answer -same arm bones in humans, cat, bat, whale -toxins affect other species in similar ways -medicines can be tested on different species Evolution - Answer change in allele frequency in a population over time Antibiotic resistance - Answer -initial bacteria population was polymorphic -one strain was resistant and proliferated after antibiotic treatment -natural selection acted on the population and changed allele frequencies BMP4 gene - Answer -influences beak development -high expression means bigger beak -ectopically expressed in chickens Myths about evolution - Answer -goal directed -hierarchy -optimal phenotype Why doesnt evolution produce the optimal phenotype? - Answer -fitness tradeoffs (ie peacock tails, morning sickness) -genetic correlation (changing one feature can change another; ie suboptimal tooth arrangement in humans because of smaller jaw) -historical constraint (species have to evolve from ancestors) -formal constraints (physics) -temporal constraints (mutation is slow) Factors that change allele frequencies - Answer -natural selection: increase or decrease in frequency of certain alleles -genetic drift: causes allele frequencies to change randomly -mutation: modifies allele frequencies by introducing new ones -gene flow/migration: introduces alleles from a different population HWE assumptions - Answer -no gene flow -no genetic drift -no biased mating -no natural selection -no mutation HLA locus - Answer -chromosome 6 -encode for proteins that bind to antigens -females preferred males with different HLA (not a good study) -not in HWE -must be natural selection or biased mating Heterozygote advantage - Answer -alleles must be codominant (have a phenotype that is different from either homozygous) Directional selection - Answer changes the average value when one extreme is favoured Stabilizing selection - Answer less extremes, reduces variation (ie birth weight) Disruptive selection - Answer favours the extremes, increases variation Negative frequency dependent selection - Answer fitness is higher in rare phenotypes