BIOL 201 1st Edition Lecture 8Outline of Previous LectureI. Additions to last lectureII. Mating Systemsa. Monogamyb. Polygamyi. Polygynyii. PolyandryIII. Operational sex ratioIV. Male-male competitiona. Ways males can competeb. Traits that formV. Female choice- direct selectiona. definitionb. ExamplesVI. Female choice- indirect selectiona. definitionb. Good genesi. Handicap hypothesisii. Parasite hypothesisiii. Arbitrary male hypothesisOutline of Current LectureI. Arbitrary male hypothesisa. Sensory biasb. ExampleII. Graph explanationIII. Runaway sexual selectionIV. Units of SelectionV. Selection between genesa. ExampleVI. Selection between organellesa. ExampleVII. Selection between cellsVIII. Group selectiona. ExampleIX. Species selectiona. Exampleb. Speciation and ExtinctionX. Inclusive fitnessXI. Kin selectiona. ExampleXII. Coefficient of relatednessa. EquationXIII. Hamilton’s RuleCurrent LectureI. Arbitrary male hypothesis- like opposite of good genesa. Sensory bias: idea that female sensory system may be biased to noticing certain cues which may lead to accidental byproduct of mating more with males who have those cuesb. Example: eye spots on male peacock feathers; eyes are important to look for in general so these draw females ini. Explains how arbitrary male preference may originateii. Reason it evolves has to do with genetic association between preferences and these arbitrary traitsII. Graph explanation- slide 17 or lecture 7a. Red line: natural selection optimum for male traitb. Blue line: if male traits evolved just to female preference alone; sexual selection optimumc. Black line: balance between the 2, equilibrium for male trait valuesIII. Runaway sexual selection: exaggerated arbitrary trait and preference that comes from indirect selection by femalesa. Female’s offspring will have preference or the trait that they prefer. Genetic association continues as time progresses.b. Female preference evolves up because the trait evolves up; until hit line of equilibriumc. All this occurs in the absence of good genesIV. Units of Selection- things as small as a gene and as large as a species can compete in natural selectiona. 4 components: traits show variation, some variation is heritable, individuals differ in fitness, and there’s a correlation between fitness and phenotypeb. need these 4 for a population to evolve.c. Can’t notice other units of selection unless they overtake individual selectionV. Selection between genes: different genes can compete evolutionarily which can counter individual selection; when certain alleles are overrepresented in gametesa. Example- mietotic drive at t locus in house mousei. Driving allele: allele that’s overrepresentedii. This allele can prevent other alleles from getting into the spermiii. Driving allele at t locus are bad for individual’s survival when they are homozygous but continue to survive when they are heterozygous.iv. This keeps driving allele from fixing in population. Selected against as far as viability but still have reproductive advantage at level of the geneVI. Selection between organelles- some organelles reproduce like mitochondriaa. Example- red mutant aspergillai. There are wild type and red mitochondria and the red type are replicating much more than wild type.ii. Red type are overrepresented but they don’t produce the genesthat wild type do so aspergilla can’t get all genes from just red mitochondria.iii. Individuals with only red will die but red replicates faster so red is favored at organelle level but disfavored at individual level.VII. Selection between cells- like cancer which is the out of control replication of cancer cells that are outcompeting other cells; bad for individual but good for cellsVIII. Group selection- was though of wrong in the 1960s; wrong ex: birds change how much they eat as food supply dwindles to ensure that more survive so that flock of birds are selected for instead of neighboring flock who doesn’t changei. This is wrong because it requires every single bird to change behavior in that group. If one didn’t then their genes would prevail due to higher fitness.ii. There has to be enough constraints on the system for selection occur despite cheating.b. Example- slide 6 on ppti. Each group is a flour bag with beetles in it indicated by numberon blockii. Group goes extinct if they eat all of the flour before the next delivery.iii. Assume that group with more than 8 beetles can’t survive on one bag of flouriv. Next gen, 7’s outcompete the 5’s because there are more of them and in final gen, the 8’s outcompete the 7’s for the same reason.v. If a 10 pops up in an 8 bag it will win in that bag but if it takes over then the whole bag will go extinctIX. Species selection- a. Example- 2 types of snails= nonplanktotrophic and planktotrophici. There are more nonplanktotrophic ones especially in more recent times when looking at fossil recordii. Have higher speciation in nonplank than plank which compensates for the higher extinction rateb. Speciation and Extinctioni. Speciation: species reproduction; one species splits into 2ii. Extinction: species deathX. Inclusive fitness: direct fitness + indirect fitnessi. Direct: get from reproducing themselvesii. Indirect: get from fact that you share your genes with non-descendent kin [like siblings or cousins] and can sometimes influence their reproductive successXI. Kin selection- promotes aid to descendent and non-descendent kini. Descendent: direct fitnessii. Non-descendent: indirect fitnessb. Example—family tree on slide 10 shows connection between two siblingsi. Top is parents and bottom is offspringii. Everyone has 2 lines going up because everyone has a mom and a dad geneticallyiii. All kids get half of their genes from each of their parentsiv. One sibling doesn’t necessarily share the same 50% of genes with their siblingv. To get probability that 2 siblings share a specific gene you multiply .5 times .5 for genes from mom and do the same for dad. Then add the 2 values together to get 0.5vi. Sibiling share ½ of their genes.vii. Which is equally evolutionarily beneficial relationship as one between parents and offspringXII. Coefficient of relatedness: the probability that a gene from one individual is identical by descent to one from another individual; used to calculate how related you are to someone elsei. Identical by descent means it’s not a coincidence; is specific gene that had shared descendent copies