Something to break up the studying for my fellow bio students: http://www.upworthy.com/van-goghs-starry-night-was-re-created-with-bacteria-its-as-cool-as-it-sounds?c=ufb1How many lectures have we had? I’ll post the dates for the ones I do have. Here is the link to the video I recorded of the second half of the review session. https://drive.google.com/file/d/0B-Ks9xtgQTbPaUZ4YmJwMzIteUE/view?usp=sharingPlease add notes from review session, I added a lot of lecture notes and would appreciate someone returning the favor! aZAlso, if we could add notes from the readings that would be awesome! I will start adding my lecture notes.Lecture Notes:2/9 Natural Selection (Part 2)Natural selection causes traits to evolve in a way the makes the mean fitness of the population to increase-Fisher’s Fundamental Theorem of Natural Selection = the mean function increases at arate equal to the genetic variance (VG) for fitness-Key Assumptions = 1) relative fitness are constant in time 2) other evolutionary forces (mutations, etc) are weak2/16Evolution by random genetic driftGenetic drift: random changes in allele frequencies caused by sampling of genes● Sewall Wright○ Frequencies equally likely to go up or down○ One allele will ultimately become fixed○ Genetic variation is lost over time● Eventually all copies of a gene will be descendants of a single copy of that gene in an ancestor● All human mitochondria descends from a single female that lived ~150,000 yearsago○ Despite the fact that she was not the only female at that time● Drift generates differences between populations that are initially the same○ Drosophila drift exlperiment■ 8 f and 8 m chosen at random to reproduce■ Follow frequency of brown eye mutation through generations● After 1 gen, frequencies of mutation differ between populations● Differences get larger with more generations● Ends up with almost all at 0 or 100%● Drift causes populations that are genetically similar to become more different-this is right, it’s in my notes too-You’re thinking of gene flow. ← the whole point was that these CANNOTmigrate bc of a physical barrier created by the road so it cannot be gene flowFactors that affect Ne●2/18Migration and gene flow.Spatial variation in traits is common. ● clover - frequency of cyanide producing forms○ defense mechanismWhat determines how traits vary in space?● Selection acting differently in each population● Random genetic drift○ snail - in college station, found all snails they could and brought them back to the lab and found that the alleles had a lot of different loci, in two city blocks showed that 25% had in one block and the other block relatively none had the allele■ so what is going on? There’s a road that separates both blocks. This causes strong isolation and very little movement between populations. ● Gene flow/migration○ movement of individuals that changes frequencies in a population■ mixes population■ can also introduce novel gene into a population that doesn’t have it■ not all movement leads to gene flow■ salmon breed with salmon born in same stream● Clines : a smooth change in a trait mean or gene frequency in space■ white tail Deer get larger as you go north. Relatively small in Texas but size increase as you go north, such as in Montana where the deer are several sizes larger○ clines can result from a balance between gene flow and selection ■ Drws y Coed, Wales (pronounced Dr-oos uh c-oy-d)■ mines that have vast amounts of copper.■ only one plant grows —> Agrostis tenuis○ plant has evolved ability to grow on copper rich soil (copper istoxic!!!)■ Adults are more tolerant than the seeds the closer you get to the mine.■ Seeds are more tolerant than adults as you get farther away from the mine■ Why? —> Wales is very windy. Not only seeds get blown around, so does the pollen. Copper tolerance is bad if you don’t have copper present. (because it inhibits growth) ● How to measure migration○ The migration rate, m: The proportion of individuals that arrive in each generation. ○ migration-selection balance■ fitness advantage +s, fitness disadvantage -s■ m relative to s■ if m <<s■ selection much stronger than migration■ populations different, reflecting pattern of selection■ if s<<m■ migration much stronger than selection■ genetic differences will be erased by migration ○ migration-drift balance■ m<<1/Ne■ drift much stronger than migration■ populations drift apart■ 1/Ne << m■ migration much stronger than drift■ populations stay genetically similar○ Measuring migration in continuous populations■ Ex. Grassy hills■ imagine you could find where a seed germinated and know where thekids will germinate. Follow from generation to the next where the individuals were born.■ could build a distribution of how far the kids are born from parent■ sigma^2 = variance in location of where a mother is and where her offspring is born■ Migration = sigma squared = 120 msquared■ units for sigma squared are (distance)2■ selection coefficient s=0.1■ width of cline= sqrt(3sigma^2/s) = 60 m■ cline gets stretched out where gene flow is.○ mutation-selection balance○ the equilibrium frequency of deleterious mutation : pa=u/s ○ mutation rate = u= 10^-5○ typical selection coefficient: s=0.03○ equilibrium frequency of deleterious mutation:■ pa=10-5/0.03 = 3x10-4○ Deleterious mutations carried by a typical person:■ about 250 loss-of-function mutations■ a few hundred non synonymous mutations■ a few hundred mutations in noncoding regionsEvolution and cancer● what is the role of mutations in causing cancer?○ accumulation of mutations, fast reproduction; as the most fit cells, outcompete the rest● Which of those mutations are inherited by the next generation?○ fast producing○ resistance● Why do most animals have separate soma Lecture 2/23● Leaf cutter ants○ Do not have the ability to digest cellulose○ Carry cut leaves back to the next○ Farmers■ Chew up leaves and feed leaf mass to farm inside nest■ Farm is basically fields of mushrooms <- ?○ Only 1 can reproduce in a colony (queen)■ Example of altruism● Altruism: A behavior that increases the fitness of another individual at the expense of theactor○ Sterile castes of insects are the ultimate example■ Queen makes all offspring while the majority are worker ants that spend their lives helping the queen to