Co-evolution Flashcards

Question

Change in AT mindset

Answer 1

Before = thinking of AT As static -- species adapted to static set of fiotness conditions --> This assumes that things stay the same from one generation to the next BUT in co-evolution we think about changing AT NOW = looking at how the AT of one species affects the AT of the other species -- In co-evolution At become dynamic

Answer 2

Overall: Static --> Dynamic AT Evolution in one species (movement along their AT) changes the shape of the other species AT - Peaks change -- change because different species change - As one population changes = optimal genetic combination for other population changes over time NOW -- the fitness peaks change through time in response to change in other popultions -- back and forth change = increases complexity in system

Answer 3

Much more difficult to quantify BUT you can quantify it Quantifying is an extension of pop gen --> Meshes popultion genetics + ecological interactions

Answer 4

Connection between ecology + adaptation -- Lotka Voltera Model of predator prey dynamics Image: Chnage in prey density/Chnage in time - V = rate/density of Prey - r = rate of reproduction - P = rate/density of predator c = capture rate b = birth rate Shared parameter = c --> capture rate (how often prey are being killed) - c = drives the sucess of the prey or predator --> can run through C - c = function of traits of predator and traits of prey - What controls the success of predator = function of the trait of predator + function of trait of prey Prey do good if decrease C Predator do good if Increase C - Both optinmize C through own traits BUT optimizng C in opposite directions - Predator/prey = comes down to rate for C - evolution = interact with each other in complex manner

Answer 5

Evolution of traits that affect capture rate are going to alter the fitness dynamics of the interacting species --> predator prey co-evolution results from evolutionary struggle over C

Answer 6

An ecologic interaction in which one species kills and consumes another - Prey = necessarily killed - Includes Predator prey + Parasistoid NOT including parasites

Answer 7

Predation is ubiquitous in nature -- across all ecosystems - Organisms are heterotrophs that kill other organisms Predator prey = easy to understand

Answer 8

Defensive traits are ubiquitous in nature -- also everywhere - Defense to predation through behavioral traits + venom + stings + running fast MEANS -- have predation everywhere + have many defensive traits --> might be result of co-evolution

Answer 9

Look at selection affecting defensive traits Example --> looking at lizards with hrons + birds (predators) - Purching birds -- have no talens = to kill prey they impale it on spike in tree (put prey on spike) - reserachers measured horns on lizards to see defensive traits and see which lizards were killed by birds -- looked at horns of killed liozards vs. horns in overall popultion of lizards to see if have selection on defensive traits Results: Lizards killed have smaller horns = have different trait values = trait is under NS

Answer 10

Have evolution of one species (evolution in lizards) BUT need reciprical evolution to be co-evolution (Evolutionary response to evolution in another popultion) - Here we have adaptation in one direction but do not expect chnage in birds because the birds can eat other things --> Therefore the chnage in lizards to be more defensice = does not have a big influence on the fitness of birds = birds won't change

Answer 11

Rough Skinned newts -- reciprocity is investigated Backgroun -- had a case of 3 people in Orgean that all died -- tehy found newts in coffee pot - Looked ot see if the newts were toxic --> grind newts and put in mice --> Small amount of new killed many mice = toxic --> has a lot of nuerotoxin Why have toxin on skin --> Found garner snakes who had eaten newts -- shows some snakes can eat them and sepcialize to eat them --> snakes adapted to eat organisms Snakes have chnage in Amino Acid in sodium channel that prevents TTX binding = can't hurt them - Molecular adaptation in predator + Adapatation in toxicity in newt --> coevolutionary arms race between species

Answer 12

Toxin itself = people didn't think that organsims should be able to evolove defenses to it Toxin = Tetrodotoxin (TTX) --> Dangerous because nuerotoxin --> Binds to all vertabres -- attatches to voltage gate sodium chanel on nervous system - Toxin shuts them down = attaches important part of nervous system -- conserved part of nervous system

Answer 13

Question = why not just fully resistant sweep through population Answer: There is a strong fitness tradeoff - making sodium channels resistent to TTX binding also makes them bad at being sodium chanels If can eat newts when available it is good to have resistence when can BUT have strong fitness tradeoff - Snakes with resistnace have a less efficent nerous system (clumpsy + slow) - Newts are slow = resistent can be resistent but they are more vulnerable to other predators Reason = Antagonist pleotropy

Answer 14

Antagonist pleotropy -- Alleles on sodium chanel = affects different traits INcrease resistence to TTX but decrease speed of nervous system

Answer 15

Which way they evolove = depends on the ecological envirnment Different in predator or different if in high newt envirnment --> plays out in complex ways How the tradeoff is resolved (what is the optimal balance between next toxin susceptibility and speed) comes down to the overall ecological context of the interaction

Answer 16

SPACE -- co-evolution relationship varies stringer across space

Answer 17

Co-evolution relationship varies stringer across space regions where newts are highly toxic = overlaps in regions where have high resistent snakes - Matched by variation in predators + varaition in resistence Leads to hotbeds correspinding to process across space SHOWS -- that looking in difefrent subdivided popultions = gives window into process

Answer 18

Geographic change in evological structures = basis of empircal framework to study Because -- looking at subdivided popultions gives us a window into process

Answer 19

Co-evolution interactions vary strongly across space -- spatial varaition is crucial for understanding process of co-evolution - If co-evolution is occuring --> can we make inferences about chnage from one popultion Hard to study co-evolution --> We are limiting to tracking evolution through time -- hard to track through time

Answer 20

Time is a limiting factor for studying co-evolution --> the reciprical dynamic nature of co-evolution plays out over many generations - Hard to study co-evolution --> We are limiting to tracking evolution through time -- hard to track through time Question we ask in studying = Is reciprical evolution taking place in popultion?

Answer 21

Example -- Parsnips --> defended from insects by producing a compund with with smell BUT have insects that specialize in eating parsnip leaves - Parsnips = have furanocoumarins in leaves --> the compund goes ebtween DNA to cause cell death - Most insects can't eat the leaves but have a worm that can attack because has high Cyt p450 detoxification Reserachers = go to feild and look at parsnips (look at furan levels) + look at worms (look at Cyt p450 levels) - Might see both are high and both are low What does this tell us -- expect that this is a back and forth process but we do not know where in process we are looking - over time we might see shift in fitness of organisms (parsnip increases and warm decreased -- as warm increased then parsnip decreases then parsnip increases and worm decreases thne have chnage in worm again) - we expect this to play out across genertions but when looking at one time point in generation you might have high fitness in parsnip and low in warmn BUT this tells you nothing about co-evolution process

Answer 22

If we study a particular population and find very high furanocoumarin levels in the parsnip and highly upregulated P450 in the caterpillars, what does that tell us? Answer: We expect this to play out across genertions but when looking at one time point in generation you might have high fitness in parsnip and low in warmn BUT this tells you nothing about co-evolution process

Answer 23

Looking across more species Example -- Looking at pigeons + bird lice --> look at traits of birds + traits of lice --> does this tell us about co-evolution driving intercation Answer: NO - can have traits that match but doesn't tell us if traits evolove due to co-evolutionary response - Could be that lice happen to have structure ro attack birds - Doesn't tell us if driven by co-evolutionary process SHOWS -- hard to know if driven by co-evolution

Answer 24

Fixed differences among species make it hard to generate testable hypotheses about the dynamic nature of coevolution -- hard to say if something is driven by co-evolution

Answer 25

Can generate testable hypothesis if look at varaition in between the hypotehsis of adpation within popultins and fixed differences among species (variation in middle of these allows us to construct better hypothesis about dynamics of co-evolution) -- varaition across subdivided popultions in difefrent ecological envirbnments tells us about hypothesis to study Previous hypthesis about co-evolution focused on adapation withon popultions or fixed differences among species --> focus on these hindered development of framework to study co-evolution

Answer 26

1. Interspecific interactions vary across populations - Co-evolution varies across popultion - Have lots of varaition (like variation in degree of sepcialization in popultion) 2. Coevolution of species interactions will also vary among populations 3. Populations differ in their degree of specialization 4. Differences in the outcome of species interactions and specialization in different ecological contexts scale up to a form a geographic mosaic of evolving ineractions

Answer 27

Used to study co-evolution

Answer 28

Used to study co-evolution -- context of how co-evolution is studied

Answer 29

Biotic + Abiotic

Answer 30

For moasic -- look at any one tile and doesn't say anything but look at all popultion and tells you more about overall dynamics of system Key to the picture = differences among popultions viewed from a higher perspective

Answer 31

We see “hot spots” and “cold spots” in the arms races In some populations the players are equally matched, when this snake/newt interaction is at the forefront of fitness for both populations In other ecological contexts -- other factors are more important for driving population dynamics so the arm's race isn't as strong

Answer 32

In predation/Prey -- We are looking at something that was always a life or death situation -- predators are evolving more effeicnetely to capture and kill prey while prey are evolving to espcape cature or defened themsleves --> It is inheritley an arms race situation - No other way to go --> constant antagonsim Similar arms race with parasites -- parasites are evoloving to take better advantage of the host's resources while the host is evolvong to defend itself against the parasite BUT there are other options on the table

Answer 33

Might have an arms race BUT not needing to be killed (like in predation) opens up other ways to play out Way adaptations affect traits that make routes of coevolution more diverse

Answer 34

Instead of escalating antagonism parasites can evolove to get along with their hosts Result: Complexity of parasite lifecycle can result in tradeoffs between different component of fitness -- Dynamics can form tradeoff in parasite

Answer 35

Fitness of parasite's growth and reproduction with host Vs. Fitness of parasites ability to be transmitted between hosts For parasites to be successful they need to leave to another host -- creates tension where have within host vs. between host dynamics - Tradeoff in different part of lifecycle is important

Answer 36

If a parasite is able to use more of the host's resources it will have a growth and reproduction advantage within the host BUT making the host too sick or killing it too quickly can negitivley affect the parasite's chances of passing offspring to anew host making the current host a dead end - Genotypes that are successful in exploiting host = might be most successful within the host BUT the genotype can be a dead end where it is good at reproducing within the host BUT might kill host before offspring go to another host Example -- Within the host --> The most virulent strain might win out within the host

Answer 37

Between host transition outweighs the within host adapataions because it is critical trait Fitness = 0 IF can't go to a new host

Answer 38

Antagonist Pleitropy drives within vs. between in adaptation - Most adaptations = driven towards getting out of host and into another

Answer 39

High fitness in host drives the host to be in bad shape that limits the offsrping going to a new host --> kill host before transmit offspring to other host = evolutionary dead end ***Shows fitness within vs. Fitness between

Answer 40

1. Selection on parasites to infliuence the phenotypes of the host in way that increases tranmission --> Extended phenotypes - The phenotypic effect in other organisms can cause selection to act on the allele frequencies of the carrier organism - Many examples in nature --> many where the parasite affects the physiology or behavior of the host

Answer 41

The phenotype affects of a gene aren't limited only to the organism that carries the gene - Effect of alleles extends beyond the organism that contains the allele The phenotypic effect in other organisms can cause selection to act on the allele frequencies of the carrier organism Example - Gall size -- extended phenotype of insect

Answer 42

1. Gyardia --> Gives you symptoms that are to get you to put the bacteria back into the water supply = extended phenotype of organism 2. guinea worm --> Larvae stage gets to the legs --> very painful --> only thing to make it feel better is to put leg in water --> the warm leaves the leg to go back to water to get eggs in water 3. Cortifects --> behaviral manipulation of host - Fungues grows in brain of ant --> makes ant leave the colony --> goes to branch and bites onto leave --> eventually spur grows out of ants brain and goes to ant mass - Maximize transmision of parasite into nest ***Humans are suceptible to behavrial manipulation of parasites

Answer 43

Opption 2 = complex lifecycles involving vectors --> to go between hosts and to get resource from host - Can be complicate life cycle with many hosts + multiple vectors Example -- Vector mediated disease - Malaria -- maquitoes are the vector (intermediary host) - Chargas -- Vector by kissing bugs --> insect takes blood and lays egg in host --> when bite they defecate where they feed -- bite itches = rub the feces into the cut = Parasite gets into body = disease

Answer 44

Intermediate hosts involved in parasite transmission - Intermediate system

Answer 45

Contol parasite by controling vector insect

Answer 46

Attenutaion of virulence --> parasites can evolove exploitative restraint if it maximizes between host tramission - Parasite can evolve to get along with the host to increase chance if going to other organism - restraint in exploitation = the host stays healthy = parasite can get to other host By becoming less virulent they can weaken the fitness consequneces for the host -- weakens the selection pressure for defenses

Answer 47

If parasite starts relaxing fitness affect on host -= decrease pressure of host resistence on parasite = host will not develope resources to fight pathogen = can evlove to tileratre --> NOW go from severe disease to having some fitness consequence but not major - Tradeoff you can expect in an emerging disease

Answer 48

Rabits + Myxoma Rabits - were a big problem in Australia -- popultion exploded --> many attemptes to control rabits - Had European rabits (European rabits in America got very sick rom Myxoma virus -- leads to rapid tumor growth in rabits --> kills rabit) Idea = use pathogens (parasites) for control pruposes --> get leath diease and infect rabits in australia --> should sweep through and get rid of disease Start = infected 100 rabits --> inject with virus -- IT WORKED well at first (50,000 --> 50 rabits) - All rabits left had not been infected -- no rabits infected live (lethality = 99.9%) - Population of rabits decrease Rabit popultion became much less dense and the limiting factor for virus became transmission BUT THEN rather than going to exictiction --> effect leveled out quickly - At 25% of popultion = NOW rabits are less dense = limiting fcator is hosts ability to infect others -- as popultion decreases the probability of infecting others decrease END = have chnage in selective pressure on virus

Answer 49

Rather than going to exictiction --> effect leveled out quickly - At 25% of popultion = NOW rabits are less dense = ability of virus killing host completley = limits fcator of hosts ability to infect others -- as popultion decreases the probability of infecting others decrease END = have chnage in selective pressure on virus Over time virulent strain decreases in popultion -- Changes so that the strain that is most common = when rabits live longer - Highly virulent virus becomes extict and most starins only kill 50% of the time but rabits loive longer --> rabits now have time to get other rabits sick

Answer 50

Shift occurs on parasite side In example -- rabbits are somewhat more resistent BUT this is small affect + not at all of the virus had't chnaged first - Easy to prove with experiment ***If virus didn't change the rabits would be extict

Answer 51

Austalia = Still have rabits + Myxoma BUT they are at a stalemate because of attenuation --> can't transmit = favor phenotype that case the host to be less sick to be able to be transmitted

Answer 52

Vector hosts do not have to worry about fitness tradeoff --> as long at the vector is alive doesn't matter how sick the host is

Answer 53

Less dense host popultion should lead to rapid attenuation in parasite

Answer 54

The strain of Myxoma introduced had >99% mortality and no infected rabbits lived more than 13 days Within 2 years, the population dropped by more than 75% Rabbit populations become much less dense – and the limiting factor for virus fitness became transmission This led to the rapid evolution of less virulent strains –allowing rabbits to live longer, and be more likely to transmit the virus to new hosts in the new, sparser populations The control effect of Myxoma leveled off, and in 5 years, the highly virulent strain was almost non-existent

Answer 55

Atenutation of virulence indicative of general dynamics we expect with emerging pathogens - If host decreases = have different pressure on parasite where expect that they will get along better with host Process -- pathogens evloving to survive grow and spread in a new popultions In the long term attenuation of virulence is a likely outcome but we can't relay on that in human epidemics

Answer 56

Issue = can't bank on human pathogens without massive mortality = need decrease in host BUT we have norms to force through our own actions To decrease without people dying = can limit contact during time of emerging pathogens Example - Omicron = less suck but more transmissible --> happened without people dying but with policy to limit transmitability

Answer 57

Something we pay attention to now -- how we model Epidelogical models come from co-evolutionary models of host parasite

Answer 58

Determined by reproductive ratio (R0) R0 = BN/Gamma + alpha + delta N = size of host popultion B = transmission rate to suceptibe hosts alpha = mortability due to infection Delta = natural host mortality rate gamma = rate of recovery from infection

Answer 59

Expected numver of secondary carriers from each primary case of infection --> how many other people will be infected by that first infection

Answer 60

R0 > 1 = can cause epidemuc --> can grow effectivley R0 < 1 = pathogen requires adapation first before foothold in popultion -- can't cause an epidemic - Many bad diease <1 Example - MERS = <1 --> only get from cammals (no human to humans)

Answer 61

Reproductive ratio = function of transmission rate (B) of parasite to host multipled by the size of the host popultion (rate of getting transmission) THEN deivided by naturalo mortality of host + death due to infection + recivery from infection Can increase R0 by increase B or decreasing alpga or gamma - Traits can be under selection to drive emerging and increase tramsnisaboloty but decrease mortality and decrease ability to recover (less sick but more sick for longer) -->THIS is the evolution we expect for Adapative topographies of pathogens through time

Answer 62

Decrease mortality and decrease ability to recover (less sick but more sick for longer) --

Answer 63

Context dependent (NOT for pathogen as a whole) - Host affects transmissability + rate of recovery --> R0 is NOT fixed parameter for pathogen

Answer 64

Humans can directley manipulate many of the factors driving R0 - try to dirve Ro down by limiting transmisability + limiting host density (policy came out of parameter for understadning co-evolution of pathogens)

Answer 65

Look at coverage of vaccine to see when will viryu change to reimerge to epidemic levels

Answer 66

Extended phenotype of virus --> when had less deadly (sick but less dyring) we stopped health measured when didn't help as much This invcreased the transmisability because less distanced = policy to increase or decrease distancing is based on the genotype of the virus = extended phenotype of the virus on us as host

Answer 67

Shoes that antagonist interactions exist on a continium

Answer 68

We can see examples of decrease in fitness determinetal of parasite to host --> continium of lethal to enetriley neurtal (commensalism) BUT the continum does not stop at zero instead it goes from nuetral to benefical interactons - See parasites + mutalists on continum with each other BUT they are connected Example -- In Myxoma see shift from lethalioty to less degree of lethality

Answer 69

Parasitism + mutalism exist on the same continuum--> if can go from lethal to moderate thne can go (evolove) from anatagonist to cooperative relationship There is pressure of to be less lethal over time AND for mutalism an organism could give resources but if cheat benefit then evlove towards lethal towards parasitic relationship = co-evolutuionary frameowrk predicts that many specialized interactions exist in the middle ambigous zone between parasite and mutalist

Answer 70

Co-evolutuionary frameowrk predicts that many specialized interactions exist in the middle ambigous zone between parasite and mutalist - Place in middle = expect place to occupy in long term

Answer 71

Joen was studting cyto-nuclear stabilty using Ameobae (removed nuclei to understand function of cell compnents) -- THEN some of his labs strains became infected with a parasitic bacteriam Intially almost all of the ameoba died and those than survived showed decreased growth and fitness Jeon nursed the infected strains for 5 years and the infection persisted BUT the ameoba got better (fitness recovered) - Ameoba increased fitness even though still infected - Before had a big die off then those thats tick around have less health issues = meybe ameoba increased resistance or had less virulent bacteria BUT it is not attenuation BUT this was NOT just the case of attenuated virulanece

Answer 72

After 5 years survivorship shifts = increase growth rate -- still infected but to lower extent NOW = have strain of ameoba that are infected with lower fitness AND have initial uninfected lines Exp -- swaped nuclei (move genetic material) to other --> swap nuclei between infected and not infected + did the same in infected - Infected --> unifected = fitness decreases - Swap infected for non-oingfected = 93% Survival rate (infected nuclues in no bacteria presnet cell = 6.6% SR) Found: Bacteria are obligate oarasites of the ameba -- had genetic change in ameoba to coorportaion with parasite End = have highly deleterious pathogen to a situation where bacteria is depended on host but host is dependent on bacteria --> evlove to cooporate and utilize the pathogen (get parasitsm --> oblogate cooperation)

Answer 73

Mutalistic endosymbiosis are very common in nature -- many may have evolved out of parasitic relationships - Commonality of symbiosis in nature suggests that they are more common than we think - Have long term relationship where organsisms live in cells of others

Answer 74

1. Aphids -- bacteria to be able to eat plant cell - Intracellular + vertically transmitted + start life living with bacteria in cells 2. Mixoctricha paradox --> lived in termites to digest cellulose - Mixonctricha by itself is build of endocymbiotyic interactions --> Not just one organism (have bacteria on outside of it that function as cillia -- involoved in motility of organisms through termite + have bacteria inside that could function instead of mitocondria)

Answer 75

Mother --> offspring

Answer 76

1. Chloroplasts --> look like cyanobacteria 2. Mitcondria --> Look like plha proteobacterium ***Thought to be derived from endosymbiosis -- derived from bacteria that have symbiotic relationships with Eukroyotes

Answer 77

Initial similarity = from microscope but then took seriously when saw mitocondria have their own genome that look like prokayotic genome --> Shows result of long term endosymbiotic relationship

Answer 78

In animals – only 35 functional genes (with very few exceptions) all occurring in the same order - genome is highly conserved --> high specilization of genome = strong pressure to stay this way Most genes functioning in mitochondrial processes now reside in the host genome – but they are of mitochondrial origin - Don't just use 35 genes -- most genes are needed for job are now houses in host genome -- prokyotic genes but in nucelar genome = shift of mitocondria genes in nuclear genome = hroizontal gene transfer

Answer 79

Don't just use 35 genes -- most genes are needed for job are now houses in host genome -- prokyotic genes but in nucelar genome = shift of mitocondria genes in nuclear genome = hroizontal gene transfer Mitcondrial genome --> host genome -- Get some exchange of genes across phylogenetic branches

Answer 80

Movement of heritable genetic material among individuals other than parent-offspring relationships - Exchange of variation within species BUT across unrelated indiviuals ***In many cases this is across species barriers ***Mitcondria transfer = one of most important

Answer 81

Hard to do: - Need whole coding region (inract coding region has to be inserted) - Inserted into place where would cause problems - Needs to be inserted in a way that it will be transvcribed +_regulated - Have big difference in geentic code (mitcondria have different code) = need to change to match code

Answer 82

Happened a lot of time but wasn't always successful --> lots of random shift won't fulfill the requirments BUT when it does NS can act fast to keep it conserved across all animal life

Answer 83

Most genes in nuclear genome = mitondiria as independent organisms seed control to lifecyle of hist --> prevents mitocndria from backslideing on continium -- can't evolove indenentley = can't backslide - Otherwise mutatios in mitocodnria in cells that is independent for growth + reprdouction -- we can expect it to cheat and stop giving cells --> prevented by horizontal gene transfer

Answer 84

2 organisms fusing to be one that NS acts on as a whole Got mitocondria from long term mutualistic relationship with bacteria

Co-evolution Flashcards

(108 cards)