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This 13 page Bundle was uploaded by Mickayla Notetaker on Wednesday November 11, 2015. The Bundle belongs to BIOL 1001-001 at University of Minnesota taught by Annika Moe and Craig Packer in Summer 2015. Since its upload, it has received 93 views. For similar materials see Evolution and Ecology in Biology at University of Minnesota.
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Date Created: 11/11/15
Lectu re 14 Evolution of Sex Monday ctober 26 2 15 1 2 3 AM Costs of sexual reproduction Fundamental processes that nust be explained in terms of individual advatnage Sexual selection Sexual reproduction Some species have separate m and f Some are both m and f Some only have female Sex fusion of genes in more than one individual Reproduction doesn39t always mean sex but also mitosis Dandelion seeds are genetically identical to parent39s cells Many insects clone themselves Why Sex Bacteria reproduce without sex Have sex without reproduction Reproduction replication of chromosome elongate and end up with two daughter cells identical to mother No sex Conjugating bacteriasex without reproduction A tube forms between them and after the conjugating they exchange chromosomes but has most of its original chromosome Sexual reproduction is costly Sex must benefit those individuals who engage in it not the species as a whole individual advantage is able to get more copies of its genes into the next generation Costs of Sex Courtshipshowing off proving to the ppl A lot of energy being spent to do this Finding a mate can be hard to find a compatible mate asexuals can just split into two STDsSyphilis chlamydia gonorrhea HIVAIDS Costs of meiosis asexuals don39t go through meiosis they just clone their cells to make an offspring Sexual females discard half their genetic material to produce an offspring Twofold costs of merosrs For sex to be common the short term benefits must exceed costs Most multicellular species are sexual Asexuality arises but doesn39t persist Asexual geckos have arisen recently older asexual lineages died out Benefits of Sex Historically sex was viewed as a trait that beneffited the species as a whole Sex generated genetic diversity allowing species to evolve But traits can only evolve if they benefit the individual that possess them Good for the individual and not the species as a whole Not all speccies are strictly male and female Simultaneous hermaphrodite each individual produces both sperm and eggs Take turns fertilizing each other Sequential hermaphrodite each individual produces sperm and eggs at different times in its life Changes sex after a time Born a female and after a certain amount of time they change into males at a certain size Blue headed fish female gt male Shrimp male gt female New Section 1 Page 1 All mammals some insects some plants xx xy All birds strawberries zw 22 Some insectsboth sexes diploid xx x All wasps bees some aphids diploidfertilized haploidunfertiized Many fish and reptiles hot male When distantly related phylogenetic groups show similar traits evidence of convergent evolution Different speices subject to similar evo pressures Trait is likely to be adaptive to species Haplodiploidy unfertilized eggs mature to be mature Fertilized eggs mature to be female Is an adaptation of some sort Mothers to control offspring sexratio Enviromental sex determination sex determined by environmental temp during incubation Cooler male Warmerfemale Female fitness is better when incubation through warmer temperatures Crocs and gators opposite Coolerfemale Warmermale Patterns of sex change and sex determination confer strong individual advantages They benefit the individuals Fish benefit by becoming a male later in life when they can dominate other smaller males Better to be a certain sex in different temps so they become that sex Benefits of sex bacteriaopportunity to spread genes to other individual Selfish conjugationone bacterium imposes its genes on another DNA repair Transformationbacteria can repair their DNA by having sex with the dead Getting spare parts in order to survive after the insult Shortterm advantage in diploids Mutation deletion Asexual when producing offspring the mutations that the mother has acquired during lifetime are all passed onto the offspring Sexual Meiosis can delete these mutations bc through meiosis not all of the mutations would be passed onto our haploid gametes Hostparasite coevolution sex allows diploids to quotescapequot parasites Parasites find our cells and can infect us Asexual once the mother is infected with the parasite it gets increasingly eaiser for the parasite to infect subsequent generations Therefore asexuals are more sensitive to parasites Sexual person acquires a parasite but if they can find a mate who happens to have a resistance gene to that parasite they can pass it to their offspring Therefore the offspring would escape the disease that one of the parents has As hosts become adapted to parasites parasites will evolve new lines of attack Sex allows host lineages to adapt more quickly Ex Bacterial infections in nematodes through time the sexual lineage is less bothered by the bacteria and the asexual lineages are more bothered by the bacteria Sexually reproducing hosts evolve to become more resistant to infections Bacteria evolve to become more infectious to asexual reproducingthe genome never changes in asexuals The nematodes are more likely to reproduce sexually when the parasite evolves to better match the host Sex in host is favored when infected by parasites sex only persists when parasites also evolve One pathogen can infect everything New Section 1 Page 2 Sex in diploids empirical data suggest that there are strong individual advantages from both mutation deletion and parasite resistance Theoretical models suggest that together these advantages can be gt2fold thus overcoming the costs of meiosis Many fundamental aspeccts of bacterial sex clearly confer individual advantage opportunity to spread genes to other individuals DNA repair Advantages of diploids mutation deletion hostparasite coevolution New Section 1 Page 3 Lecture 15 Evolution of cooperation Wednesday ctober 28 2 15 937 AM Innate instinctive behavior inborn genetically programmed and difficult to alter Hardwired Bees two components of hygienic alleles in separate loci Cross a hygienic bee with nonhygienic bee All offspring are nonhygienic females Cross that female with a hygienic male and the offspring are a mixed genotype with different specialized workers The behaviors are hardwired Learned behavior acquire or changed as a result of some experience Whitecrowned sparrowsA wild bird has a distinct pattern to its call A bird that is domesticated will also sing but because it hasn39t ever heard the distinct call its song is unique to each bird A deaf bird will also sing but because it has no feedback from its ears the song is all over the place Instincts are not purely genetic learning is not purely environmental almost all behavior phenotype involves an interaction between genes and environment quotselfishquot trait can spread even if its damaging to the species as a whole Honeypot ants division of labor Some workers hang on the ceiling and become the receptical for nectar being a living honeypot Darwin described the sterile castes of social insects who work on behalf of a queen as quotone special difficulty which at first appeared to me insuperable and actually fatal to my whole theoryquot Altruistic behaviorselfsacrificing act that benefits the recipient at the expense of the donor Lowers the reproductive success fitness of the donor while raising the fitness of the recipient How can altruistic traits evolve trait appears alturistic but donor in either being selfish or manipulated Mutualismboth parties gain immediate benefitsants and acacia treetree provides a gall for the ants to live and the ants repel leafeating insects Parasitismbroodcuckoo eggs are placed in the warbler39s nest and the warbler thinks it is her egg when it s a different species The warbler will take care of the cuckoo not because of altruism but because it was manipulated to believe the cuckoo was its offspring Indirect kin selection via inclusive fitness altruism directed at relatives 1 Direct fitness personal reproductive success 2 Indirect fitness increased reproductive success of relatives as a result of quotaltruistic behaviorquot weighted by coefficient of relatedness Kinship parentoffspring and full sibling r12 and halfed for each generation Coefficient of relatednessr probability that another individual shares an allele by common descent Hamiliton39s rule rBgtC the coefficient of relatedness times the benefit to recipient out weights the cost to the donor rBgtC being nice to someone rgtCB being nice Altruistic behavior can evolve by kin selection when 1 Relatedness between two individuals is high 2 Cost is low 3 Benefit is high New Section 1 Page 1 quotkindnessquot most common between close relatives Eusociality cooperative brood care looking after the larvae Reproductive castes queens and workers overlapping generations Eusocial quottruly socialquot insects al ants many bees and wasps termites some aphids amp beetles Ex Leafcutter ants a leafcutter cuts the leaves another ant carries and another is the sentry who makes sure no one is following them or trying to steal their leaves then they put it in their fungus garden where ants tend to it and cultivate food for the hive All at the service of the queen These altruistic insects come from the halploiddiploidy sex determinism branch Honeybees workers feed the pupa and uncap the eggs and do otherjobs in service to the queen They are all female so diploid Drone male haploid They are getting ready to go out into other nests and spread genetic material to other hives and mate with the queens Honeybee Castes amp Haploidiploidy Unrelated Drone X Queengt queen makes eggs She will make workers who are fertilized drones who aren39t fertilized and eventually new queens who are fertilized and can reproduce When a new queen is produced she will take a proportion of her mother39s workers with her to start another hive Sisters are related to each other by 34 motherdaughter12 sisterbrother14 Workers help their mother produce more sisters sisters are more closely related to each other than to anyone elseeven their own offspring 34gtCB HD is not essential for eusociality to evolve Termites are diploid and so are naked mole rats Both have queens and workers that tend to different jobs around the nest Ecological constraintsif a young animal is unable to breed successfully on its own its best option will be to act as a fulltime helper With nothing to lose C is zero since direct reproduction is impossible Ex Fairy wrens Inside the breeding territory of the wrens there are three individuals a breeding male and female along with a male helper which is their son All the helpers stick around and help the parents with offspring The females can easily find a mate but because there are so few females there are a surplus of males Naked mole rats constrained by the fact that they can39t live outside their tunnels and the tunnels are already full of other relatives so they cannot reproduce except for the King and Queen Reciprocal altruism unrelated individuals that can recognize each other and will reciprocate Altruism based on future favors c cost to altruist b benefits to recipient bcnet benefit of reciprocation f bgtc then altruistic patners do better than nonaltruists Reciprocity only favored when cheaters are excluded from further exchanges Ex Two individualsgt one is nice to another C B then some time later the other is nice back BC BC Now they are equal Each person has incurred a cost by participating but also benefitted from the nicety On the other hand one is nice to another C B But the other doesn39t reciprocate back still C 3 The one is lucked out by not getting any benefit from the altruism New Section 1 Page 2 Requires individual recognition and good memory Recognizing the individual as someone who will reciprocate and remembering them in case they don39t and won39t make the same mistake Common in insects birds and mammals Many species show highly developed systems of kin recognition Reciprocity only confirmed in humans and possibly a few primate species With really good cognitive abilities Human kindness humans seem kinder than what the biological model can predict Heroism runs pretty deep in humans Fairness expectations in 15 month old kids toddlers are shown movies that hide the distribution of cookies to two recipientsand are then shown a slide with either an unfair or fair outcome The kids stare longer at an unfair outcome But if people are being treated unfairly Human kindness is in our nature And it is what truly distinguishes us from the animals Could partially be our high levels of cognitionbut could be something else stay tuned to find out New Section 1 Page 3 Lecture 16 Selfish genetic elements Tuesday November 3 2 15 92 AM Selfishness at the molecular level Have a evolutionary advantage to replicate themselves even if they are damaging to the organism Meiotic drive unequal representation of each homologous chromosome in the gamete sexlinked genes benefit from distorting sex ratio Egyptian mosquito y chromosome destroys the X chromosome so the mosquito can only have sons NucleusDNA and chromosomes are there Mitochondriahave own DNA Reproduce separately from the cell Only transmitted in cytoplasm of egg or ovule Not in sperm or pollen Selfish mitochondria kill off the Y chromosomes so that it will be passed on to the daughters of the organism Chloroplastshave own DNA Reproduce separately from the cell Only transmitted through the cytoplasm of egg or ovule not in the sperm or pollen Transposonsquotjumping genesquot that spread themselves throughout the genome Indian corn The gene D jumps down the genome onto the C gene and instead of producing a normal purple kernel it produces yellow Much of the junk DNA has been randomly inserted by transposons Spread between individuals Plasmids reside inside bacterial cell Like Transposons and can insert itself into the main chromosome And can also transfer from one bacteria to another Repressor genes protect against P elements contagious transposons in Drosophila Selfish genetic elements can move from one area of the genome within organisms or from one individual to another Virusesselfish genetic elements that quothijackquot the molecular machinery of a host to manufacture a phenotype The phenotype improves the virus39s ability to infect new hosts Consists solely of DNA material in a protein coat they have no metabolism Attacks a cell by injecting its DNA into the cell uses the nucleus to make more of its own DNA breaks down the hosts nucleus uses the host39s mechanisms to create even more of its DNA and the protein coat and finally when it leaves it kills the host cell Bacterial defense against viral infecction restriction enzymes cut DNA at specific sites that are found in Virus39s and it gets rid of it therefore surviving the attack Humans virus comes into the cell the macrophage detects the virus and captures the virus inside itself the macrophage activate helper t cells which activate T and B cells B cells form plasma cells which make antibodies which bind to the viral antigen antibodies attach directly to viruses and to infected body cells and signal their destruction Clonal selection theory Clonal formation of trillions of different immune cells each one recognize a specific protein Immune cells that attach to quotselfquot are destroyed Cells that detect foreign proteins antigens proliferate via mitosis Plasma makes the antigen and stores the information in case host is attacked by same virus Viruses are polyphyleticmultiplt origins many viruses are more closely related to their hosts thatn each aother Viruses are classified by host then by genetic material DNA RNA Viruses have repeatedly New Section 1 Page 1 evolved from transposons virus transposons with a pheonotypes Viruses arise from selfish genetic elements that develop phenotypes to assist their movement from one host to another Transposons and viruses are important in genetic engineering and gene therapy Genetic engineering cutting DNA with a restriction enzyme Where the DNA has been cut the ends want to latch onto something sticky ends and if we insert DNA from another organism they will latch onto the new DNA Introduce the modified plasmids to target bacteria Plasmid inserts new gene into bacterial chromosomes Can have bacteria produce human proteins or value human growth hormone Viral vector inserts the DNA into the cell which transcribes the DNA The virus doesn39t integrate into the host cell the inserted DNA only stays there as long as the cell stays alive Genetic engineering harnesses the quotselfishnessquot of plasmids and viruses to promote the production of beneficial proteins Smallpox has killed 100million people in the whole world over 3000 years until it was eradicated in 1977 survivors enjoyed lifetime immunity from the virus Major had a 27 mortality while minor had 8 Chinese found out if they infected themselves with the minor form and had a smaller chance of dying of it would be immune for the rest of their life Smallpox has DNA as its genome which is really stable which means it doesn39t have very many mutations and doesn39t evolve as quickly as other viruses will Smallpox only infected humans so once everyone was vaccinated it no longer exists HIV selectively attacks helper T cells a vital component of the immune system HIV is an RNA virus that mutates very rapidly Reverse transcriptors convert RNA into DNA and inserts into host DNA leading to permanent infection Spanish flu 19181919 killed 50100 million people in 2 years and the high mortality rate for 1534yr oldsusualy these people are the least effected by disease RNA virus Two types of surface types on the cell Reassortment when two flu viruses attack the same cell but when they leave they leave with all the RNA and mix together creating a new virus that had never existed before in nature Vaccines don39t work for that new virus because the virus is so different from what the vaccine attacks Resistance depends on the virus Small pox two outcomes either die or survive and have lifetime immunity stable without many mutations so antigens can detect and effectively eradicate it HIVRNA Virus integrates permanently into host genome attacks immune system and evolves rapidly so cant accurately attack it FluRNA Complex pattern of recombination Prior exposure doesn39t protect against the newer strains bc they are so different from one another Selfish genetic elements Meiotic drive Y chromosome and mitochondria distort sex ratio in their favor Transposons spread across individual39s genome and also between individuals Viruses selfish genes with a phenotype which allows it to better infect other hosts Defenses against selfish Meiotic Drive countered by supressor genes Transposons countered by repressor genes New Section 1 Page 2 Viruses restriction enzymes in bacteria cut away the virus In humans numerous mechanisms attack the virus New Section 1 Page 3 Lecture 17 Origin of Life Monday November 9 2 15 128 PM Early Ideas Which came first RNA DNA or proteins Can life really come from nothing or are all organisms come from preexsisting forms World39s first controlled experimentFrancesco Redi 1688 Flies with rotting meat Previously thought flies came from rotting meat But what about scum and slime that always appear to come out of nowhere Experiment on solution and is isolated from the open air Scum happened on the one open to the air All living things are descended from direct ancestors Life doesn39t generate from inanimate objects but life did come from somewhere Origin of the Earth Our solar system formed abt 5 bya Earth formed 457 bya via accretion of smaller bodies The bombardment generated so much heat that lighter elements were vaporized and consisted only of heavy elements Early atmosphere was thick with ammonia Vast amounts of volcanoes and lightening in a soupy sky This lighting can synthesize organic compounds amino acids and nucleotides Origin of macromolecules Clay crystalsmicroscopic sheets each point on each surface has a slightly different electrical charge They may have provided the template for the first nucleotide chains Each nucleotide attracted by a specific charge Nucleotides bonded together in a chain along the clay crystal Monomers individual nucleotides Abiotic RNA strandsindividuals that are close enough to create a strand Selfreplicating eventually it was able to replicate itself RNA can act as an enzyme that assists its own replication and promotes protein synthesis Protein synthesis with enzymes are more accurate RNA capable of selfreplication specialized RNA molecules improve the efficiency of replication Compartmentalization Once replicators developed a toolkit to enhance selfreplication they need a toolbox Find safe havens between sheets of mica Mica has high levels of potassium The first cell walls could have selfassembled from fatty acids Single nucleotides can permeate the quotcell wallquot but the RNA strands cannot leave the protocell RNA World Sites essential for translation consists entirely of RNA In the world there are RNA ribosomes and protein They can selfreplicate and create two identical cells Selfreplicating RNA that come into contact with lipid vesicles and have a quotshelterquot away from the rest of the world Through evolution they develop reverse transcriptase which can produce DNA which becomes the quotlibraryquot of genetic information DNA is more stable than RNA so this was beneficial to acquire RNA viruses have more mutations than DNA Molecules subject to the same laws of ns as living organisms New Section 1 Page 1 RNA molecules that were best able to selfreplicate became more common Proteins that assisted RNA replication became fixed Enzymes improved efficiency of replication Proteins manufactured the cell39s own lipids to ensure stable environment for replication DNA molecules preserved favorable RNA Early life Life appeared on Earth abt 3835 bya they were bacteria and archaea Archaea thrive in extreme habitats most similar to the early volcanic ventsand obtain metabolic energy from heat Oceans formed 44 bya thermal vents in the deep oceans 350 degrees C Archaea occupy harsh environments with little or no oxygen The earliest liked heat and weren39t good in oxygen but then the world changed bc the bacteria thrived on Sunlight instead of heat They used photosynthesis to create a sugar and gave off an oxygen molecule This changed the atmosphere forever Oxidationburning Burning iron to rust by exposure to oxygen New Section 1 Page 2 Lecture 18 Diversity of Life Tuesday November 10 2015 1145 AM Symbiosis and the evolution of organismal complexity Evolution of EukaryotesgtFungi animals and plants Struggle for survival usually implies competition But the history of life includes many examples of cooperation Mutualism any relationship in which both parties gain immediate benefits Symbiosis Where two different species live together in direct contact Endosymbiosis Where one species lives inside the cells body of another species Eukaryotes Animal and plant cells Mitochondria and Chloroplast are only passed in egg or ovule The mitochondrion Primary site of cell metabolism Aerobic Contains its own DNA Circular chromosome Reproduces by binary fission Closest relative is alphaproteobacteria After oxygen was more plentiful in the atmosphere the Eukaryotes Somehow the achreabacteria took in the eubacteria but didn39t digest it and through evolution the Eubacteria evolves into mitochondria This engulfing but not digesting gave rise to Eukaryotes Protistssingle celled eukaryotes Large enough to have the mitochondria live inside them Multicellularity Larger size division of labor btw cells and greater potential for physical complexity Colonial bacteria can move as a unitmotiity depends on how well cells stick together Slime molds single celled eukaryotes that can merge to form colonies of gt20000 cells First Eukaryotes to live on land A sexual reproductiongt spores gt emerging amoebagt meiosis gt sexual reproductiongt sexual fusiongt aggregated amoebasgt migrating colonygt fruiting bodies Amoebas are separate cells Surface proteins are so complex that clones can only stick to each other At this point there is a division of labor within the quotstuckquot amoebas Some become the stalk of the slime mold while others stay within and remove bacteria from inside the slug Acellular slime mold haploid spores and fertilization then mitosis at this point amoebas fully merge plasmodium then a mature plasmodium then finally a mature sporangium Heterotrophs have to eat other organisms to survive Fungal external digestive organs Goes into the cells of a plant and eats the plant 1st multicellular land organisms Myclium turns dirt to humuspant food Produces antibotics Largest organism in the world is a mushroom that covers 2384 acres and has been alive for 1000s of years Origin of animals Arose from protists as well but a different branch Earliest ancestor of the animals Choanoflagellate colonial protist produces lots of cells and they reproduce by cell division Colonial protistsgtholow spheregt cell specializationgt infoldinggtprotoanima New Section 1 Page 1 Trichoplax when it finds something to eat they bend around the thing and the cells temporarily turn into digestive cells AutotrophsOrganisms that can produce their own organic nutrients Protists and Cyanobacteria were evolving side by side until a protist engulfed but didn39t digest it Evoloved into a chloroplast These are the ancestors of multicellular plants that are alive today Arise as the levels of oxygen were increasing in the atmosphere Endosymbiosis explains the origins of mitochondria and chloroplasts allowing anaerobic organisms to become aerobic and heterotrophs to become autotrophs Multicellularity evolved seperately in fungus animals and plants allowing division of labor and larger snze Endosymbiosis gut symbionts termites have protozoa in their stomachs that take in the wood chips and the bacteria in the stomachs of the protozoa breaks it down into cellulase that the organism uses to survive Bacteria in our guts helps to digest our food Antibiotics kill off good and bad bacteria In order to restore the good bacteria stool transplants are the best way to go Bacteria in different areas of our body helps protect us against harmful things we take in over our lives Symbioism is fundamental to the health of multicellular organisms Lateral Gene transferantibiotic resistance can transfer from one hospital pathogen to another Resistance in animal pathogens can transfer to human pathogens Bacterian have exsisted for gt3 billion years so LGT must have happened before on the tree of life New Section 1 Page 2
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