Evolution Lecture 14 Study Notes.docx

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Western University
Microbiology and Immunology
Microbiology and Immunology 3300B

Evolution Lecture 14 Study Notes **READ 1. What are adaptations? -adaptations are traits that have evolved due to persistent natural or sexual selection (over many generations) in response to an agent of selection -if a trait is proposed to be an adaptation we ask: what is the adaptive function and genetic basis 2. Distinguish between adaptation and local adaptation. -adaptation is a phenotypic difference among species -local adaptation is a phenotypic difference among a population -can be a noun or a verb to describe an adaptive process 3. What are some models to test for adaptive functions? -selection experiments (selection operating on a specific trait) -comparative methods (comparing between species or between populations which is within species – comparing a difference in a particular trait; relating this difference to an ecological selection factor) – could be with or without phylogenetic correction -tests of adaptive hypotheses – i.e if its an adaptation it must have a function 4. What is an example of a selection hypothesis? -studies that relate the phenotype to fitness 5. What is an example of a comparative method with no phylogenetic correction? -among species; bats that live in larger groups tend to have a larger testes size -probably due to male-male competition (phenotypic – environment correlation) -agents of selection could be biotic or abiotic factors in the environment 6. What is phylogenetic dependence? -traits are more closely related to each other then others -if you have a phylogeny where ABC and related and DEF are related; same trait = adaptation evolved independently – only using extant species -2 groups; plot; only 2 points to show that a larger group size = larger testes size; not enough data to statistically support that 7. What is phylogenetic independence? -if we instead use sister species shown in phylogenies that we can get more reliable data -study the contrasts between them instead of studying a group with a common trait -have extant and ancestor species -instead of asking teste size, ask when they diverge/why -use sister species as a separate point -plot the group size vs teste size for each sister species -4 points; see that there is a correlation (if the contrasts are correlated then can conclude that a larger teste size = large groups) *figure 10.13 8. Discuss the comparative method with corrections. -without phylogenetic correction: only using extant species; get a positive correlation between social group size and teste size -with phylogenetic correction: not as steep a slope and not as many points but its stronger because it is phylogenetic independence -shows a stronger adaptive response 9. What is a comparative method within species? -compare phenotypes across environments to test adaptive hypothesis -studying body size between salkeye salmon -bigger size is more attractive to females; more likely to mate -but this inhibits swimming -hypothesis: bigger body size in beaches (male-male competition) -large hump is a sexual selective trait – metamorphose -local adaptation = reflection of body depths 10.What are some experimental tests? -jumping spider and fly (has wing markings and a particular waving motion) -deters the spider 11.What are the alternative hypothesis? -do not mimic spiders and don’t deter predators -flies mimic jumping spiders but behave like this to deter other non-spider predators -mimic jumping spiders to deter predation by them 12.Results? -had 5 different treatments -tested each hypothesis with the jumping spider and other predator 13.Discuss the experimental quality. -can discriminate multiple hypothesis -have well designed controls -handle control and experimental groups similarly -minimize confounding effects -sufficient replication -consider how the data will be analyzed 14.What were the results? -retreated in control and when wings were cut and re-glued -stalked/attacked/killed when house fly had real fly wings, real fly had no wings and with a house fly 15.How do we test for a genetic basis? -use a common garden experiment -testing for a particular adaptation -different genotypes in a common environment; if they’re different then its genetic 16.How do we know if it is due to genetic basic or phenotypic basis? -page 11 on slides ** -positive slop to the right (2 different lines) -shows genotypic variance and phenotypic variance -population 2 has a better phenotype in both its environment population 1s environment compared to population 1 -also does better when its in one environment compared to the other environment -2 separate lines horiztonal -genotypic variance; doesn’t do better in one environment or the other just better than population 1 -lines together; positive slope = phenotypic variance -lines together horizontl = nothing 17.What were the reaction norms in achillea? -low elevation in Stanford and high elevations in mathers -have similar phenotype in own environment (around 30 stems) but when transplan
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