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
-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
-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
-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)
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
-mimic jumping spiders to deter predation by them
-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
-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