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02/15/2012°Biol1001 Wednesday February 15, 2012Fitness Fitness is compared between individuals oGenotypes/phenotypes within a population oDepends on reproductive success relative to other organisms Genotype vs genotype Comparing individuals within the same population oOr two populations that belong to the same species Ex. Fruit FlyoYou cannot determine fitness without information without the environment Fruit flies that can survive wi/o food for a long time vs those that survive a short time without food You don’t know how much food is available in the environment, therefore you don’t know if the onesthat survive shortly die Fitness depends on the specific environment that the organism livesin °°Adaptation Any trait that allows an individual to out reproduce individuals without that trait oAdaptation, verb and nounProcess by which organisms become better matched to their environment Can be a structure or behavior
As long as it is genetically heritable °°Case Studies °Galapagos Finches Is beak size heritable? oTo figure out: measure trait in parents, measure traits in offspring, see if there is a relationship Took average of beak depth of parents, measured beak depth in offspring, Found that parents with deep beaks produced deep beaked offspring Did beak size correlate with food? oLarge beak resulted in better large seed consumption1977 -> Drought, rain decrease Plant diversity changed oHard shell protects better against water loos in plant seeds 660/751 birds diedocompare the ones that survive and the ones that died ones with deeper beaks survived better that ones who could notdue to being able to break those hard shell seeds that survived the drought the ones with not as deep beaks could not break the shell and died off Natural Selection: Directional one phenotypic extreme was selected against and one phenotypic extreme was selected for
Directional selection The entire bell curve graph shifts so that the average goes toward one of the previous extremesFixed -> 1 allele survivesWe see zooplankton moving from larger phenotypes to smaller ones because larger ones are more easily hunted Fish start producing much earlier because the larger ones are eaten , so they reproduce before they get too big A extreme rainfall happens Small soft seeds prevail Change in beak depth occurs Smaller beaks reproduce more -> increased allele frequency Average stays the same °°°Natural Selection Stabilizing Selection reduces both extremes of a population oNo change in average value of a trait over time oReduction of genetic diversity Premature babies vs Extra Large babies Premature babies aren’t fully developed (risky Extra large babies risk immune system fuction, diabetes, getting stuck in the vag (super risky)So these two types of babies don’t survive as much ?
oMedical Technology allows a lot of these babies to survive (against natural selection) o