Speciation Flashcards

Question

Example phylogenetic tree

Answer 1

See 7 groups of varaition = 7 species Seems objective --> Take in genetic varaition -- if evolution is about genetics then this seems useful Problem = NOT USED OFTEN

Answer 2

Gives an Incomplete lineage story --> Part of reason why varaition in genes doesn't always match varaition in species - Variation in ancestrak Might get one allele in one popultion and another alleles in other popultion BUT don't know if it will end up that way - Ancestral vraiation is evoloving -- which alelles goes to fixatino changes Get different answer for phylogeny based on gene used = NOT objective

Answer 3

Start -- 3 types of flies - 3 groups of drosphila with different morphs -- we suspect they are different species The phylogenetic relationship is different based on 2 different genes --> the two genes gives two answers regarding the flies relationships to each other - Might get one answer if lookat one one gene or another -- NOT reliable way to deleniate if something is the same species

Answer 4

Useful -- If species do not interact with each other Example -- looking to see if they vary genetically + if they are different phylogenies from different clades) - Look across genome regions = name 2 species in group that was thought to be one Good if have seperation between organisms -- can conclude that they are not exchanging genes BUT we do not know if they were in the same habitat if differences would break down ***Phylogeny might be the best in some cases even if not the best

Answer 5

Overall: Species are co-occuring organisms that occupy different niches (Adaptive zones) - Popultions that are adapted to particular combination of resource bases, predators/parasites, and envirnmental factores in a particular place - Organisms in the same habitat but different nuche --> Have different requirements (Ex. Different predators) - Different set of ecological charachteristics = seperate ecological popultion = difefrent species IDEA = comes from niche exclusion - If niche is the same then one will go to extiction - If niches are different = niche that dirves discontuniuty = drives species level diversity

Answer 6

States that two popultions that completley overlap in niches cannot coexist in the long term - If overlap = can't co-occur through time

Answer 7

1. It is impossible to define a niche extrinsilcally of the popultion occupying it - Can't define niche without organisms that occupy --> only can define for organism that exists in that space 2. Niche are not like parking spaces 3. Species do drive each other to extiction due to intense competition BUT does tat mean they weren't species to begin with ***Not used over the years

Answer 8

Application in asexual organisms Used in things like prokaryotes - Useful in some cases -- shows how to miantain discontuniuty + drives discontunity in asexual organisms

Answer 9

Overall: Species are groups of interbreeding populations that are reproductively isolated from other such groups - Discontiunity has to do with connective gamete pools of reproductive systems IF they are exchnaging alleles THEN this is no longer the case --> no longer reproductivley indeoendent = discontinuity is harder to maintain - If popultions are not reproducing they become evolutionary independent Variation is discontinous because reproduction is discontinous

Answer 10

Not very useful for understanding process of speciation --> Not used by evolutionary biologists for understadning how species arise BUT they are useful when in limited situations

Answer 11

Species are meaningful levels of biologic organization that drives discontinuity in biology

Answer 12

Much more used + get to the crux of what speciation is about

Answer 13

Articulated from after the modern synthesis -- formed the basis of a lot of speciation reserach Important reveleation in understanding what species are + gets to idea of how species form Start to couple pattern + process

Answer 14

Variation is discontinous because reproduction is not continous Different species remain different because they are not exchanging genes through reproduction

Answer 15

The popultions are no reprodcuing with each other + no migration connecting them --> means the evolutionary forces acting ion popultions or within species are independent of each other - Drift + migration are indepent = species are in independent evolutionary trajectories - Forces in one popultion does not affect the other ***If popultions are not reproducing with each other they become evolutionarily independent

Answer 16

Evolutionary indepence --> closest thing we have to a unfied species concept When we talk about discontinuity -- see different groups that are evolutionarily independent -- different trajectories through evolutionary time

Answer 17

1. Requires absolute complete reproductive isolation 2. Species designations are alwats relative -- interbreeidng popultions that are isolated from other groups 3. If we are basing this on the potential for interbreeding its hard to say anything about popultions that aren't actually in contact

Answer 18

In intial incarnation -- people held closley that it requires absolute reproductive isolation in order for them to be considered different species and anything less is not speciation -This is a high hurdle to set for discontinuity if it requires absolute barreiers to gene flow - This does NOT match with what we see in nature reproductive Isolation = Different species are incapable of prodcing fertile offspring with each other in the wild

Answer 19

Doesn't match what we see in nature --> Hybridization is common in nature between groups that otherwise stay seperate -- NOT blending together - Real species can have hybrids + gene flow

Answer 20

Means that the evolutionary forces acting on a popultion do not have any baering on the evolutionary outcome of another popultions

Answer 21

Species designations are always relative --> you are reproductivley isolated from ANOTHER group (not just looking at one group -- looking at two groups relative to each other) - Looking at how they are relative to each other NOT intrinsic about a group itself Makes BSC less than satisfactory

Answer 22

One of the biggest when thinking about diagnostic --> the BSC functions poorly because it is hard to test whether things are caopable of reproducing with each other if there were in contact - If we are looking at groups that are not interacting this is hard to determine EVEN if do an experiment in lab --> they might not breed in the lab or they might BUT even if they do breed in the lab they might never in nature because of the nature of where they live - Means that applying BSC in a lot of situations where people think about two things being diverged gets hard in practice

Answer 23

Pointed out in 1990s -- documentaing rayes of hybridiztion in wild for organisms that we otherwise consider species (match strong discontinuity and functional evolutionary independence)

Answer 24

1. Polar baers + grizzly baers

Answer 25

1. Polar baers + grizzly baers - They are very different (easy to tell apart) --> We theerfore call them different species and they mainatin discontinuity (speciation) BUT they can hybridize and their hybrids are fertile - Seen in zoos (mate readily) - NOT just done when in caoptivity --> happens in the wild -- occuring at increased rates as climate chnage is the blending the linkes of habitats -- they are pushed together into the same range and ar hybridzing at significant rates BUT we are not seeing them collapse as one baer -- still have discontinuity even though they are exchanging genes in nature Shows: Things we think of as good species that match discontinuity and evolutionary independence can still form hybrids and do so in anture + shows that the species can be phylogenetically distant and still mate 2. Ducks + geese -- can find hybrids easily - 76% of duck and geese in britain form hybrids with other spcies in nature (form fertile hybrids) 3. Chicks + guinea Foul -- shwos get hyrbids from things further in ohylogentics distances - Produce hybrid offspring even though they seperated 35 million years ago - Example = Sturgeon + American paddle fish -- mate --> get hybrid offspring (don't know if it is fertile) BUT the species have been seperated for at least 200 Million years

Answer 26

Shows that discontinuity can be maintained even if have some amount of gene flow Shows: Things we think of as good species that match discontinuity and evolutionary independence can still form hybrids and do so in anture + shows that the species can be phylogenetically distant and still mate

Answer 27

If hybrids/fertile hybrids are seen in nature --> MEANS we need to soften our view on BSC Means we do not need absolute barriers to gene flow because we can have some amount of gene flow and discontinuity can persist Result: Led people to make different version of BSC that softens view point

Answer 28

Says that species are groups that are mostly reproductivley isolated - Less satisfying than an objective idea of what species are

Answer 29

Hybrids can become own species -- often occurs in plants

Answer 30

First idea of complete reproductive isolation = most problamatic Complete repdouctive isolation often does not match up with the discontinuity seen in nature --> hybrids are fairly common and many are fertile YET discontinuity exists Solution -- often soften BSC to mostly reproductively isolated

Answer 31

Overall: Species are genetically distinguishable groups of individuals with few or no intermediates when in contact with other such groups - Came because of rapid nature of hybrids in nature - Thinking about organisms occupying diffrent genetic spaces Gets close to idea of evolutionary independence

Answer 32

1. Still relative -- have to compare to another group 2. Somehwat wishy/washy -- "few or no"

Answer 33

Genetic varaition that no longer overlaps between species because evolutionary forces in one popultion do not act on evolutionary forces of the other BUT STILL the differences are mainatined in the face of some gene flow GSCS = gets closer to idea of evolutionary independence

Answer 34

Effect = to homogenize allele frequencies between populations High migration = we are not able to maintain genetic differences --> cam't maintain genotypic clusters unless there are other forces acting STRONGLY against migration

Answer 35

If there is some migration and they are not collapsing (they still have discontinuity) --> tells us that migration is not meaningful - If popultions are able to maintain discrete genotypic space even if some reproduction is still going on migration is no longer consequential THEREFORE the popultions are evolutionarily independent Means the two popultions are still evolving independently without needing absolutely no gene flow - One popultion does not effect the other depsite some potential continuity

Answer 36

Example: Start -- have two groups in two environments (in two niches within the same envirnmnet) Start = only red + blue (no intermediates) IF exchange some genes --> NOW have some purple - Migration acts to hemogenize allele frequencies SO if we have exchange of genes why doesn't migration do that? Occurding to BSC -- The purple (result of gene flow) would be sterile = they can't make offspring = get some hybrids BUT the hybrids can't go anywhere BUT what if we have fertile hybrids --> They do not have to be sterile they just ahve to be lower in fitmess - Lower fitness could be due to reproductive abvility (decrease in fecundity) --> People focused on things that deal with repdoruction because thinking about reproductive isolation as sole driving force of isolation BUT there are ways of affecting reproduction that doesn't have to do with repdouction directley - Instead -- indiviuals could just be ecologically unfit --> could be infit in envirnment - Example -- The purple might not camoflouge as well = stands out = gets eatten - OR Hybrids could have lower fitness because hybrid genomes are not as well adpted as parental genomes would have been Selection of intermediates = important way we view process of speciation rather than just looking at reproduction system directley Overall: Hybrid just needs to have low fitness --> if pruple does poorly alleles aren't liley to spread between blue and red = popultions can stay distict

Answer 37

Lower fitness could be due to reproductive abvility (decrease in fecundity) --> People focused on things that deal with repdoruction because thinking about reproductive isolation as sole driving force of isolation BUT there are ways of affecting reproduction that doesn't have to do with repdouction directley Instead -- indiviuals could just be ecologically unfit --> could be infit in envirnment - Example -- The purple might not camoflouge as well = stands out = gets eatten OR Hybrids could have lower fitness because hybrid genomes are not as well adpted as parental genomes would have been

Answer 38

Selection of intermediates = important way we view process of speciation rather than just looking at reproduction system directley

Answer 39

Hybrid just needs to have low fitness --> if pruple does poorly alleles aren't liley to spread between blue and red = popultions can stay distict

Answer 40

In practice genotypic clustering is not very different from soften view of BSC --> two sides of the same coin BUT considering them sepertlet allows us to look at pattern vs. Process Pattern = what are species Process = how do species evolove

Answer 41

Species are genetically distuiguishable groups of individulas maintained in contact with other such groups --> this pattern is driven by the evolution of reproductive isolation - Discontinuity = driven by diffrent forms of reproductive isolation to keep them apart BUT not absolute barriers to complete genomes

Answer 42

Complicated

Answer 43

No one species concepts is perfectley applicable across all of the varaition we see

Answer 44

Have issue of dealing with purley asexual organisms _ the range of sexuality in other organsims - Main limits of either end that many species concepts run into Concpets = only work whenb there is the right amount of sexual reproduction going on IN BSC -- issue of sexuality = if have too much sex or not enough sex

Answer 45

Issue when have too much sex (rapid hybirization) OR not enough sex - Issue = some groups do not conform to biologic continuity that we epxect on species levels Examples that are probabmatic for any of our species conepts: - Have many exmaples in plants because they are self pollinating (Asexual linages) + Hybridize between unrealted forms = complex varaition 1. Hawthorns -- 180 species OR 2000 spoecies in the world --> because hard to know what is reproductivley isolated when have a huge range of varaition from asexual to sexual on a regular basis 2. Oaks -- have asexual and rapid hybridization -- makes drawing boarders between species hard

Answer 46

Speciation poses a bit of a paradix for evolution by NS For a whgile was a paradox for evolutionary biologists --> Hard to know how this happens - Issue = breakdown of reproductive compatability that used to be able to interbreed -- why should this happen Paradox: Shouldn't NS favor inivividulas caopable of breeding with everyone + How do popultions go through a phase of limiting reproductive options

Answer 47

Breakdown in reproductive compatability = causes decrease in reproductive sucess = reduces fitness --> Why evolove to be not compatable if ancestors were -- breaks down an important part of fitness

Answer 48

Thought about how to go through phase from interbreeding to stage of being incompatable Do we need string ecological divergence or absolute reproductive isolation -- how do you breakdown the compatability Led people to start thinkning about geopgraohic context of speciation

Answer 49

For a long time biologists were hung up on geographic context of speciation - Emphisis on this has fallen out of favor (partly because reality is more nuanced) BUT it is still important to discuss Looks at how the ranges of popultions relate to eachother throughout the process of speciation

Answer 50

Has string consequences for ease ordifficulty of speciation

Answer 51

Issue = two species ranges now might not reflect the ranges when they were diverging - What we see now might not be the context that organisms diverged in BUT we want to know what is the context of divergence - The current distrubution of completley reproductivley isolated taxa doesn't necessarily tell us about the nature of their divergence

Answer 52

1. Allopatry (Vicariance + Peripatric)

Answer 53

Complete geograohuc seperation of popultions during divergences -- seperated range NO migration at the start (m = 0) -- totally different regions during divergence Two forms: 1. Vicarance 2. Peripatric

Answer 54

Seperation of a large popultion into two parts --> one large popultion that gets cleaved into two - Seperation of an otherwise connected population - Seperates what was one larger interbreeding popultions into two seperate popultions Could happen if a barreier appears OR if organisms shoft range around a geographic barrier Example -- if near a mountain range --> might go over and split across the mountain range -- NOW they evolove indepentley because seperated and by the time they come back into contact they may no longer be compatible

Answer 55

Allopatry caused by colonization of a distant habitat from a larger popultions - Started as a big popultion and founded a small satelite popultion - Founder events will play a role Example -- On a mainland --> have an island off of coast and maybe have one pregnant female goes to island and starts a new popultion in island (now seperated)

Answer 56

Drift -- have strong effects at the start of the process - Strong founder effects causing rare alleles in the samll popultions might be important - Only issue in periparty If found a new satlite popultion with few indivdiuals = involves a lot of drift from the start

Answer 57

If have flies on mountain and have a satelite mountain range (there is a big seperation between the two) and happen to get one individual on the other mountain that founds a new popultion Strong founder effects causing rare alleles in the samll popultions might be important

Answer 58

BOTH -- have a geographic barreier from gene flow form the start -- no genes exchanged because the two popultions are physically seperated - BOTH -- results in absolute barrier to gene flow between popultions BUT it is worth having them as seperated because only peripatric has drift

Answer 59

1. Panama -- Vicarinace -- seperates from pacific from atlantic between NA and SA --> before had one mass contecting the two (befoe the waters were connected) -- THEN have a land mass that sperates them -- now different species on sides of land mass because reproductivly isolated when land mass rose - Example -- snapping shrimp seperated 2. Bambies + Chimps -- diverged due to vicarinace --> Seperated form each other after popultions were seperated by the congo ruver - They ae bad swimmers = popultions seperated - Now evolove independently 3. Example peripatry --> Hawaii - Because we know the timing well -- we know about how peripatric divergence occurs - Spiders are different species on the different islands 4. Drosphilla in Marchyus Vs. seychells -- two different species - The mainland insect goes to island and now is three species NOT one - Peripatry = includes many model systems for geentoc basis of reproductive isolation

Answer 60

Many have to do with island colonization

Answer 61

DRIFT -- plays an important in peripatric divergence

Answer 62

Snapping shrimp seperated

Answer 63

Geographic seperation BUT not complete isolation -- often occuring in adjoining habitats - Alongside each other (Adjoining habitats) - NOT seperated ranges -- have adjacent ranges --> ranges touch + could overlap to some gree in the middle HERE -- m>0 -- Divergence still occurs even in the face of some inital gene flow

Answer 64

m>0 -- > not complete geographic isolation - Overlaping individuals can mate Divergence still occurs even in the face of some inital gene flow

Answer 65

m>0 -- > not complete geographic isolation - Overlaping individuals can mate Divergence still occurs even in the face of some inital gene flow

Answer 66

Might have flies adapted to different habitats that vary by elevations - Might have high and low eleveation ones -- they ate geographically isolated because they stau in different habitats but the habitats touch each other -- range where the habitats are next to each other Seen in Andes with buterflies thta are low and high land that are likley in some contact

Answer 67

No geographic seperation among diverging popultions - Diverging occurs in complete overlap of popultion ranges - More restictive for speciation to occur

Answer 68

m > 0 --> Over 0 for all individuals in both popultions Have some emergence of discontunity while still conneted

Answer 69

Divergence begins as polyphenism that eventually leads tp evolution of some reproductive or genetic incompatability that leavds to discontinuity in a single habitat - Have some emergence of discontunity while still connected

Answer 70

Modes of geograohic varaition = range of potential migration and gene flow in the process

Answer 71

Easy to explain speciation at m= 0 BUT as increase potential migration = gets more restrictive to explain how speciation occurs in the face of more gene flow

Answer 72

Ways of classifying context of speciation BUT also classifying the traits involoved in the process - Look at ways phenotypes can affect evolutionary independence of popultions - Looks at ways the gene flow can be restricted in popultions More nuanced view -- covers a range of migration levels

Answer 73

Need to think about when in the life cycle gene flow can be restricted and when gene flow can be restricted in formation of zygotes - One of the ways to classify isolating mechanisms is by the timing of their action along the life cycle

Answer 74

1. Premating -- no mating - Isolation occurs before gametes are exchnaged 2. After mating but before zygote formation -- mating but no zygote - Isolation due to unsucessful fertalization 3. Post zygotic -- have zygote but have an issue in zygote that prevents effective gene flow across popultions - Isolation due to problems with the offspring's genotype

Answer 75

1. Behavioral Isolation -- Might be because of difference in mating behaviors that make two organisms unattracted to each other - Organisms fail to attarch each other as mates 2. Mechanicam isolation prevents reproductions -- geneticals do not fit toegther - Reproductive structures are incompataible for mating Example -- Bird with corkscrew fallace 3. Ecological traits -- Divergent adaptation leads to decreased mating events across popultions Example --- Peackock dancing spiders --> do a dance - Two species might not exchnage genes because do not find the dancing attarctive - MIght not be impressed by dance

Answer 76

Ecological traits could play a role in premating isolation - COuld have an ecological adaptation that prevents gene flow 1. Example -- Different polinators -- flowering plants polinated by different insects (one might be polinated by an insect and one might be bat polinated) --> pollen won't flow from one to the other 2. Could have different mating areas -- one might dance in open and one might dance in isolated area 3. Could have different reproductive seasonality (different mating seasons) - If one mates in jine and one mates in augast = have barrier that keeps them apart

Answer 77

Most occur when gametes themselves are incompatible (sperm and egg can't make zygote) - Often gametic isolation --> Gametes are transfered byt fail to form a zygote Might be because of incompatible cell types -- not reacting right to get gene in egg cells (Fail to react properly) or the sperm might not be able to survive the female reproductive track Example -- Gemete incompatability for broadcast - Sessile organisms that don't move -- cast ganetes out into the ocean and hope they mix and form zygote --> might spew spew out but when sperm and egg comes together nothing happens (seen in Sea urchins)

Answer 78

Have some amount of gene flow -- when mate they make zygotes but some isolation makes zygote not effective gene flow between popultions - Hybrids might be bad at reproducing or bad at surviving or both Can have: 1. Sterelity 2. Inviablity -- fitness is low

Answer 79

1. Intrinsic 2. Extrinsic

Answer 80

Context independent -- doesn't matter what environment - Independent of the environment They are bad no matter what

Answer 81

Decrease in fitness = depends on the envirnment - the lower fitness is due to envinrment In a lab they might be fine

Answer 82

1. Grizzly Baer + polar baer--> They are fertile -- might be extrinsic post zygotic that keeps them apart Intermediate is not good at being a polar baer + not godd at being a grizzly baer --> they are only bad in the envirnment (not in the zoo) = extrinsic - In the zoo it is fine It is only bad in envirnment = exitrinsic 2. Hybrids that are steile -- MUle --> intrisic becaise doesn't matter where the Mule lives they are always sterile

Answer 83

Not often one mechansims that keeps genotypic clusters apart -- as speciation proceeds often have more than one mechanism acting in different parts of the life cycle -- act in a sequential pattern - Multiple mechanisms can work together in a sequential fashion Example -- have 80% isolation due to premating = only 20% gene flow after THEN can reduce that even more to create repdouctive isolation

Answer 84

Overall: Have reduction from full compatability at each stage Example -- have 80% isolation due to premating = only 20% gene flow after THEN can reduce that even more to create repdouctive isolation Can measure the strength of reproductive isolation for different mechanisms in system in organsms and measure them indepentley - Can go into the lab and say that you have some traits that causes 65% reduction in potebtial matings and of the matings that occur 55% reduction in ability to form zygotes and after mating the offspring that form from those zygotes have 90% reduction in fitness - Shows different measures of mechanisms + how their act in a sequential fashion Overall: Have 65% further reduced by 55% which which is further reduced by 90% -- cumalative reduction to 84.25% at post mating and 98% reduction by the end SHOWS -- any one factpr by itself might not be very good but the different traits acting toegtehr limit to less than 2% because of the way that they interact with each other

Answer 85

In the absence of any gene flow -- incompatibilities are easy to eexplain -- easy to explain that given time these incompatabilities are almost ineviatble - If they are seperated geographically then they evolove indpenetley then when they come back together there has been enough time that they become incompatable = speciation is complete

Answer 86

Use Dozbhnzke Muller model --> key is to explain how reproductive incompatability evoloves in the absense of gene flow Considers incompatiblility evoloving at multiple genes

Answer 87

Explains how incompatabilities form --> key is to explain how reproduction incompatability evoloves in the absence of gene flow Consideres incompatibility evolving at multiple genes - Considers interaction between more than one locus (epistasis) Overall: Given amount of polygenic traits + Amount of epistasis in nature -- if two popultions evolove independently = end with epistatsic differences in different contexrs

Answer 88

Explains Inevitable model of reproductive isolation is driven by inevitable buildup of epistatic incompatibilities between organisms Example -- Have a post mating Pre zygotic isolation mechanism -- have sperm + egg issue - IF you have locus A that is a cell surface protein on the sperm and locus B for receptor protein on egg surface Start = A and B are compatible with each other in intial population THEN you separate the two populations physically = evolve independently -- if evolve independently = mutations in one population will not occur in the other population -- the timing of mutations + what mutations occur might be different In one population might get a varient in A --> now have individuals with a not A -- and a needs to be compatible with B gene IF have a change in A and both A and a are compatible with B (this needs to be the case otherwise a would not rise in population - a works with B = increase in a Then the second population is fixed for A (they never have the mutation) BUT in the second population you get B --> b -- b needs to be compatible with A -- eventually get fixation for p NOW Pop 1 = foxed for a Pop 2 = Fixed for b WHEN population 1 and 2 come back together = have an issue because a is not compatible with b (a is compatible with B) = breakdown in compatibility in fitness Overall: Given amount of polygenic traits + Amount of epistasis in nature -- if two populations evolve independently = end with epistatic differences in different contexts

Answer 89

Overall: Given amount of polygenic traits + Amount of epistasis in nature -- if two popultions evolove independently = end with epistatsic differences in different context Different popultions eveoloving indepentley sets the stage for downstream evolution = get some incompatabilities that effect many things (effects all stages) --> Indendent evolution cuases genomes to be incompatible because of inevitable buildup of epistasis

Answer 90

Easy to see in Allopatry because mutations don't occur in context of each other Example -- Have a diploid organism with 6 chromosomes THEN have seperation barrier (because allopatry) --> mutation in habitat 2 in locus a AND in other popultion have D --> d -- NOW have subsequent changes in bases The The mutation occured in indiviuald popultions and went to fixation that leads to genome wide seperations - Mutation in one popultions might be favored in both habitats but only occurs in one and stays in one because they are seperated IF you take away barrier -- if exchnage genes might get initial chnage in one popultion in one habitat thats a works well with d BUT NOT D --> Ability to get estabiloshed is reduced

Answer 91

If lock A and a on the same chromsome = always inherited together but still hvae gene flow -- HAVING SEX = have recombination = put incpomatible getes = hard for sepeciation to get started

Answer 92

People thought that speciation requires allopatry (requires geographic seperation) -- because if have any gene flow = harder to explain genetic popultions for spceiation = easy tp say that it will only occir if have barriers to gene flow driven by geography

Answer 93

Stopped thinking about other geographic modes (not considering modes of speciation) BUT this is now changing

Answer 94

DM type isolating mechanisms evolve easily when no gene flow BUT they are harder to evolve in situations with more migration They are almost inevitable in pure allopatry given enough time, but the conditions for reproductive isolation to evolve in sympatry are much narrower

Answer 95

Figure: Shows genotypic clustering -- Groups of ants that form distict clusters in genomic space Overall -- looks at genomic varaition in seed dispersing ants in eastern NA SHOWS -- variation in genomic space across 284 colonies of ants thought to be one of two species - Showed that the species designation based on morphospecies is inaccurate with genomic data In Genomic clustering model -- have 3 species and a whole other set of less distict clusters that represent some earlier phase of speciation process before string reproductive isolation and evolutionary independence is completed

Answer 96

Distcit discrete clustering -- what we expect to occpuy spcies level divergence -- get few or no intermediates between individuals in genomic space vs. other groups of colonies that have a lot of intermediate indivoduals indicative of ongoing hybridzation

Answer 97

If geographically seperate popultions (have allopatry) = not exchanging genes with the other AND if we allow enough time --> THEN the independent evolution occuring in isolated popultions will inevitably lead to epistatic incompatabilities that result in breakdown of reproductive compatability between popultions

Answer 98

For epistatic incompatabilities -- requires epistasis

Answer 99

requires epistaisis --> changes in a couple of genes that interact with each other that allow breakdown of reproductive compatabiulity

Answer 100

Answers how should a breakdown in reprodycrtive sucess evolove if a fundemental poart of NS is the ability to repriduce with memebers of popultion Answer in DM = if they are seperate popultions and evolove indepentley (mutations in one popultion occur in one and not the other or occur in different orders) = sets the stage for subsequent evolution = get inevitable buildup of epistatic incompatabilities

Answer 101

Functinons best in complete absence of gene flow or migration = best in pure allopatry

Answer 102

Was such a sucessful model that is became the null for understanding how new species arise for decades Many thought that because DM incompatabilities occur so readily in isolated popultions that perhaps this explains ALL of biodiversity (that geographic happenstance in seperated popultion either through viracariance or allowparty) might explain all species diversity because process happens automatically given seperation and time Came out of Modern synthesis

Answer 103

Might not match biodeiveristy in all contexts --> is diveristy at species level reaoly just because of rivers and mounatins splitting popultions -- doesn't match with understanding of how biodiveristy is structyred + importance of ecological interactions in maintaining biodiveristy

Answer 104

Explains how reproductive isolation can evolve in the absence of hard geographic barriers HERE -- speciation can occur when ecology is driving force between seperation of popultions

Answer 105

Overall: Shows how ecological adaptation can result in reproductive isolation = have speciation if no geographic component separating populations Background: Fruit flies --> lay eggs in ripe fruit -- larvea developes feeding in fruit --> -- THEN triggers the fruit to drop and larevae crawls out and gies to soil --> When there is hawthron in the fall the next year = the flie leaves the round and starts again - Life cycle is synced with avalibility of ripe fruit -- intamiate relationship between insect and host plant - Before = all adapted to infesting hawthorn fruit THEN colonists introduced apples to NA -- didn't affect flies for a while BUT in 1850s in NY some of the flies shifted from attacking Hawthrons to attacking apples Entomologosts documenting this shift were reading Dawrins work and started talking to Dawrin about this being a potential case of formation of a new species in action -- Dawrin agreed BUT the entomologost was hit by a train and everyone forgot about the story until some reseracghers picke dit up and started looking to see if this was a case of formation of a new species NOW -- this is well studied and is the best supported case of ecological speciation in nature

Answer 106

Shift = required adapatation in 2 Phenotypes 1. Chemosensory response to fruit volitle -- find host by smelling them - Know the apples prefer the complex voltile blend of apple odor and hawthrons prefer hawthron odor - As they look for host plants where they will find mates and lay eggs apples to to apple trees and hawthrons go to hawthorn tree 2. Life history Time - Apples fruit 3-4 weeks earlier than hawthorns --> Apple flies come out of ground 3-4 weeks eariler than hawthorn = shirfts the mating sead of the two insects apart through time - flies only have a single life cylce per year = need to be tightly synced around windows of avalble host resoruces - Even if on the same host plant they are out at different times -- as hawthron hatch the apples are dying

Answer 107

The two traits (life history + smell) = forms the basis of pre-mating isolation - Difference in chemo repsone = causes them to go to difefrent trees + have different phenology (seasonal timing) --> driving mating season apart = creates strong but incomplete reproductive siolation

Answer 108

Incomplete --> premating isolation limits portential gene flow to 4-6% per year --> Means the strength of reprductive isolation = 94-96% 4-6% migration = BIG reudction from random breeding but migration is a string evolutionary force that is able to homogenize allele frequnecies between popultiomns exchanging genes MEANS -- even in the face of 4-6% migration rate --> THE difefrence still persistnce because also have post zygotic dilution on system - Post and pre allows differences to cause consistent allele frequencey difefrences to build up between the popultions when in sympatry - differences are genome wide - Know there is no geographical compoenent because we know where the shift occured

Answer 109

Even in the face of 4-6% migration rate --> THE difefrence still persistnce because also have post zygotic dilution on system - Post and pre allows differences to cause consistent allele frequencey difefrences to build up between the popultions when in sympatry - differences are genome wide - Know there is no geographical compoenent because we know where the shift occured

Answer 110

Looked at chemo sensing -- looked at pre mating and post mating level Figure -- Looked at strong phenotypic differences in chemo behavior Have apples + hawthron in wind tunnel that has a blend of volitle that makes apple odor - Apple respond positivley to apple -- Hatwhorn have limited response to apple Have Apples + HAwthron in wind tunnel that makes Hawthorn odor - Hawthorn respond positivley to hawthorn Y axis -- looked at phenotypic response of upwind flight SHOWS pre mating component of phenotype -- if apple preferntially go to apple and hawthrons go to hawthorns = seperating where flies find theor mate and lay eggs

Answer 111

Looked at chemo sensing -- looked at pre mating and post mating level Figure -- Looked at strong phenotypic differences in chemo behavior Have apples + hawthron in wind tunnel that has a blend of volitle that makes apple odor - Apple respond positivley to apple -- Hatwhorn have limited response to apple Have Apples + HAwthron in wind tunnel that makes Hawthorn odor - Hawthorn respond positivley to hawthorn Y axis -- looked at phenotypic response of upwind flight SHOWS pre mating component of phenotype -- if apple preferntially go to apple and hawthrons go to hawthorns = seperating where flies find theor mate and lay eggs

Answer 112

1. Dominance -- Heterozygotes between apple and hawthron just prefer Hawthron (hawthron effect masks the apple effect) OR apple is dominant to hawthorn phenotype - Here = get initial reprodtive isolation from pre mating BUT when have hybridization event have substantial gene flow back into one popultion = if this was teh case (if apple is dominant) = woulod have a lot of hawthron genes going into apple popultion in hybrid that is behavirally apple 2. Co-dominance -- lead to hybrid flies likeing both --> repsonds positivley to both - POOR barrier to gene flow - If all hyrbrids were just able to move between hawthron and apple mating popultions = increase gene flow between them -- if indiviuals can respond to both why shoudl they adapt divergentley why wouldn't they all be generalists between hawthron and apple if that opens more ecological oppertunities for them

Answer 113

Took F1 from 3 populations and compared them to initial apple and hawthorn blends + have some mixes of different groups of volatiles Result: Found that there was no response of hybrids to apple or hawthorn blends -- ONLY small percent response to some mixes of blends - Go form 100% response of upwind flight in pure bred to complete lack of behaviral response = hybrids seems to be inert MEANS -- hyrbids prefer neither --> if can't respond behaviorally to either of teh fruit smells in feild in nature = can't find matyes = can't ocaposit = very low fitness = reason why this is strong post zygotic isolation

Answer 114

Hyrbids prefer neither --> if can't respond behaviorally to either of teh fruit smells in feild in nature = can't find matyes = can't ocaposit = very low fitness = reason why this is strong post zygotic isolation - Hybrids = intert = no response = can't find mates

Answer 115

If put hyrbids in cage with males and females = can get them to mate in the lab -- means that they are not intrinsically sterile they are ecologically sterile -- in context of ecological envirnment they will never be able to find mates

Answer 116

Seen in feild experiment looking at differential trapping of apple and hawthron based on odor blend in nature Experiment -- Have two bated sets of lores -- has shiny red christmas ornaments in sticky material to trap flies - Some of parafin lure that releases the volitle (apple or hawthorn odor) + have a control trap with blank paraffin Looked at Apple in Apple orchord and hawthron foron in stands of hawthron trees and visa versa - Seeing how hawthorn flies react to apple in their envrinment and visa versa Results: See percent of flies caught on sticky odor rather than blank control - Expect 50/50 -- if catching by chance - In apple orchard = caught more than expected by chnace in trap with apple odor - Hawthhrn odor in hawthron trees = catch more hawthron than expected by chnace compared to control - Hawthron in apple area AND apple in hawthorn area --> get far fewer flies on baited lure than by chnace -- catch more on blank SHOWS -- not just a matter of phenotype about prefermaces not that hawthrons like the smells of hawthron and apple like the smeel of apple --> SHOWS that they avoid the smell of alternative host fruit (nit only about preferance but about avoidance behaviuors too)

Answer 117

Not just a matter of phenotype about prefermaces not that hawthrons like the smells of hawthron and apple like the smeel of apple --> SHOWS that they avoid the smell of alternative host fruit (nit only about preferance but about avoidance behaviuors too) NOT unexpected based on the kind of chemo sensory ecology of insects in general --> specialized insects need to navigate a chemcially noisy world -- many plants making many voltiles that might overlap = need to make the right decision on roght plant smell to follow for getting a good host plant

Answer 118

Example = crab apples --> very acidic = the flies can't survive on them = if the flies makes a mistake and follows the smell of crab apples rather than hawthorn or apples = they will ovaposit into the crab apple = that will give low fitness = insects are wired to prefer a good habitat BUT also wired to avoid bad habitats

Answer 119

Found based on genetic cross Likely have 4-5 genes involoved --> have a mixture of pro apple loci or pro hawthorn loci AND anti apple or anti hawthron loci - Apple flies have genotypes to prefer apples BUT also activley avoid hawthorn blend - hawthrons have pro hawthorn and anti apple genotypes ***Know the nueorophysilogy of the phenotyope well for how the brain is wired

Answer 120

When Apple and hawthorn come together in hybrids NOT the prefernace for specific fruit that matters it is the avoidance part where the hybrids end up avoiding both --> Avoids hawthron and avoids apple = casues teh flies to ebcome ecologically sterile -- flies with genotype for anti apple and angti ahwthron end up ebing anti to both

Answer 121

Driving the strong post zygotic isolation is NOT just the effect of single loci it is the compbination of preferance and avoidance alleles = what overall phenotyope there is and therefore what fitness you have is not just based on alleleic state of one locus -- it depends on the allelic state of multiple loci = epistasis

Answer 122

Kinds of ecological barreiers in order for them to be effective = they are also epistatic too Have epistasis even in cases where have ecology driving reproductive isolation and speciation - Have epistasis in the same way have epistasis when have allopatry in DM model MEANS the most effective isolatinmg mechanism often evolve epistasis

Answer 123

Since have epistasis -- on AT = see two different potential high fitness outcomes (one specializes in apple and one in hawthron) with some fitness valley between the two Means have one popultion specialized at one peak and the one specialzied on the other peak -- generating few or no intermediates because have such low fitness

Answer 124

Have morphologically residential flies in genus that infest a wide numver of host plants where fly poputions are divergnetly specialized on the same kinds of traits involoved in chemo sense + life cycle timing in a way that have different species of flies attcking different host plants Apple flies = have being doing this for 160 years BUT others have been opccur the past 10,000 or 100,000 years Have range of ongoing levels of divergenes that indicating of adapting radiation More recentley -- some of flies where introduces via apples in 1970s and have shifted to hawthorn populations there - see not just evolution of speciation in past century but in the past few decades

Answer 125

have divergent ecolgical specialization and speciation not just in teh case of a single new species being generated but a whole diversification of a group of organisms based on tehse kinds of ecological speciation process

Answer 126

When ecologic oppertunities post fitness tradeoffs that generate epistatic incompatabilities in ecological phenotypes the process of ecologically driven speciation and adpative radaition might be pretty common in nature

Answer 127

Speciation is process of taking varaition in popultion and splitting it into varaition at species level -- into different evolutionary independent lines

Answer 128

Can think of speciation as the interface of micro and macro evolution

Answer 129

Thinking from allele freq change within population to type of larger scale evolutionary change between populations or between species Speciation is connection between two levels of thinkning about evolutionary change

Answer 130

Thinking from allele freq change within population to type of larger scale evolutionary change between populations or between species Speciation is connection between two levels of thinkning about evolutionary change

Answer 131

Idea of adaptive radiation is not limited to the fruit flies -- a lot of major studies understanding evolution process driving diversification have takem place to understadn adaptive radiotion in general Example -- Figure --> study of Adapative radiation of lizards in Greater antilles → difefrent ecoligcall oppertunities on islands lads to different diversification of lizards into different ecological groups through time

Answer 132

Not one speciation event BUT have multiple speciation events based on adaptations to many ecological environments Example -- Lizards --> specialized based on ecological opportunity to increase biodiversity - Have different islands + difefrent ecologies = different behaviors + phenotypes --> Causes to diversify in many ways

Answer 133

Adaptive radiation puts speciation at the interface between micro and macro evolution (variation within species to between species variation to evolve to macro evolution processes)