-reciprocal altruism

-eusociality

-parent-offspring conflict

-between related individuals

-vampire bats (same % of pre-fed weight will add 16 hours to a starving bat that would add 6 hours to non starving bat... so more valuable to those genes)

reciprocal altruism- altruism between NON-KIN

-for selection to result in reciprocal altruism:

1)cost to donor must be less than or equal to benefit to recipient

2)recipients that don't reciprocate are punished (no cheating)

likely to evolve when:

1)stable groups

2)multiple opportunities

3)individual remembers donor's behaviour

4)altruism is bidirectional

extreme form of reciprocal altruism

social system with:

1)cooperative care of young

2)reproductive division of labor

3)over-lapping generations

-common in insects, also found in snapping shrimp and naked mole rats

Hamilton proposed haplodiploid systems are predisposed to eusociality

-hymenoptera (bees, wasps, ants)

-sterile female workers (2n)

-males (n) from unfertilized eggs

-if single father, r within generation > mother-daughter

(sisters .75 related insead of 0.5, but 0.25 to brother instead of 0.5)

-females in haploid systems benefit more through inclusive fitness, rather than reproduction.

1)females increase fitnes by helping queen produce sisters

2)relatedness to sister (0.75) is higher than to brother (0.25), predicts 3:1 F:M ratio, BUT queen invests equaly to produce sons and daughters.

-who wins? workers or queen?

Termits caste system is regulated by pheromones produced by king and queen

-inhibit workers of the same sex from molting into reproductive adults

-death in the royal family or an increase in the size of the colony decreases pheremone concentration

-sex-specific soldier pheromones regulate numbers of male and female soldiers

Wood ant offspring ratio

-queens produced eggs 1:1

-at hatching female biased

WHAT ABOUT EUSOCIALITY?

-haplodiploid is important, but is it the reason why so many hymenoptera are eusocial? (decrease level of relatedness)

1)predict workers favour production of females, assumes same father

-most multiple sires (17.25 [mates with 17 males on average]) average r of workers is <0.3 (less than parent/offspring)

2)multiple queens

3)phylogeny

-not all haplodiploid organisms are eusocial and vice versa

*eusocial behaviour evolved multiple times

-not present among all haplodiploid insects

-appears to also coincide with nest-building behaviour (not causal.. simply a correlation)

-cold blooded mammals

-not moles or rats

-elaborate subterranean tunnels, colonies of 70-80 with single queen and 2-3 reproductive males

-female workers not sterile (benefit?)

-2N, XY sex determination

-1.4:1 M:F

Did DNA fingerprinting

-band sharing as high as 0.88-0.89 (identical twins is one)

-85% matings are parent offspring or fullsibs

-average r=0.81 (other non-eusocial mole rats r=0.46..still really high!)

-eusociality in naked mole rats due to high inbreeding? (poor dispersal abilities)

Naked mole rat social structure may be produced and maintained by intimidation imposed by the queen

-non relatives shoved ad intimidated much more

siblicide- in birds and mammals it is common for siblings to kill each other while parents seemingly do nothing

-blue-footed booby

-facultative siblicide

-smaller sibling is killed only when food is scarce

-extra reproductive value

black eagle

obligate siblicide

-smaller sibling is always killed regardless of food availability

-insurance reproductive value (what if one egg doesn't work?)

Can parents reduce siblicide?

-when above birds crossed, and parents and offspring all unrelated, masked booby (obligate siblicide) encourage siblicide by holdig back food

-parents and chicks responsible

-in facultative siblicide, an increase is observed.

PLAYING FAVOURITES
-unequal distribution of food

-are there advantages to siblicide? (surviving offspring benefits)

-removing badgenes

PARENT-OFFSPRING CONFLICT
-ill isbling gains future offspring for one offpspring

-parent net loss of future descendents

-tradeoff

Aspects of the natural history of an organism that are related directly to survival and reproduction.

Life history traits include:

-age of first reproduction (maturity)

-number of reproductive events (parity)

-number and size of offspring (fecundity)

-longevity  (life span)

"timing is everything"

"Should I breed or should I grow?"

Energy allocation:

total energy = maintenance + storage + growth + reproduction

trade-offs: resources used for one function cannot be used for another.

-energy for metabolism and repair used throughout life, while emphasis on growth early in life and reproduction later in life

-as brood defence (i.e. parental investment) increases, parental survivorship decreases but offspring survivorship increases... another tradeoff.

-balancing presents investent with future reproductive efforts

-must consider future and present reproductive success when considering investment

-sexually mature at birth

-continually reproduce

-high quality offspring

-large number of offstrping

-live forever

thrips egg mites... females produce once, sexually mature at birth

senescence: decreased fertility and probability of survival

-aging should be opposed by natural selection

-theories on why aging occurs

...rate of living theory: populations lack genetic variation to respond to aging

...evolutionary theory: trade off between reproduction and repair

-individuals selected to maximally resist cell damage and repair cell/tissue (i.e. at physiological limit)

-if true, predict:

1)because cell/tissue damage byproduct of metabolism, rate of aging corresponds to metabolic

2)because selected for max. repair, can't increase longevity through further selection

PREDICTION 1: all species have same amount of energy through their life

-some spend it slowly, and others quickly

-so... species with higher metabolic rates have shorter lifespans? (NO!)

-compare bats with species of same size.. no correlation.

PREDICTION 2: can't select for longer life span as already at max

-natural population brought in lab selected for... early reproduction and late reproduction

-longevity in late reproducing selected lineages significantly higher

-but did it also affect metabolic rate?.. first 15d only

Not clear if differences in metabolic rates explain differences in longevity

-idea that organisms age as result of intrinsic physiological limits has persisted

-cumulative effects of cell divisions

---each cell has set number of cell divisions (other than germline, cancer, stem)

---telomeres

-repeating units at ends of chromosomes

-100-1000 telomere sequences on the ends of each strand

---humans TTAGGG

-during each replication, telomere sequence will be lost, but this allows 100-1000 divisions before main body of DNA affected

Telomerase

-telomerase enzyme contains an RNA fragment with the complimentary sequence

-essentially replaces lost sequence from 5' end

-present in germline cells

-telomere length in humans negatively correlated with age.

-in Leech's storm petrel, positive correlation

-if natural selection can increase longevity, why  hasn't it?

-aging results of inability to repair damage

-deleterious mutations

mutation accumulation hypothesis- effects of natural selection late in life are weak, aging alleles only mildly deleterious

-trade-off between reproduction and repair

antagonistic pleiotropy hypothesis- mutation affects two different life history characters

MUTATION ACCUMULATION HYPOTHESIS

-allowed adults to reproduce for 4-5 days , used offpring to start next generation

-late acting deleterious mutations not allowed to affect individuals, those alleles should act neutrally and increase in frequency

-accumulation of alleles does have an affect

ANTAGONISTIC PLEIOTROPY HYPOTHESIS

-what if a mutation causes an individual to reproduce sooner AND die youner

C. elegans age-1 gene

-hx546 allele increases longevity by up to 80%, otherwise "normal

-no change in frequency of hx546

-what happens in natural conditions?

-mimicked natural conditions and fed every 5 days (about 2 generations)

-used eggs produced in first 24h to start next generation

BUT.. upon closer inspection, eggs used were from yonger adults and indirectly selected for + allele (got opposite of expected.. frequency of hx546 decreased)

-inadvertently selecting for wildtype

Collared Flycatchers

-first year breeders have lower reproductive success later in life, although their lifetime reproductive success was higher

When should an individual start reproducing?

How many offspring should an individual have?

-why don't some species maximize each reproductive event?

How often should an individual reproduce?

**Drosophila... premature death at old age has little effect on fitness, can compensate by laying one more egg early on (as survival probability is so low at high age)

Selection favours clutch size that produces the largest number of surviving young

-assumes probability of offpsring survival decreases with increased clutch size

-no trade offs

Great tit. highest survival% clutch size is at 12..., but mean clutch size is 8.5... why aren't they laying more eggs?

Why lay fewer eggs than you can support??

-future reproduction

-inclusive fitness

-survival/health

**The smaller the mothers clutch size, the larger the daughter's!!!!

Care and incubating energy..

precocial- ready to go (longer incubation)

altricial - (very dependent

albatross lays 1 egg every 1-3 years, start at age 8-14!

-quail lay way more

semelparous-

-reproduce once and die (no future reproductive costs)

-annual plants, salmon

iteroparous

-more than one brood uring lifetime, fewer yong

-balance current investment with future costs

-eg. perennial plants, bears

intergenerational time is very important!!

-assuming same lifespan (1yr) and same number of offspring (3)...

-if breed every 3 months, end up with 120 offspring, if breed every 12 months, get 3.

Lots of small offspring or fewer large offspring

-assume trade off between size and number of offpsring

-larger offpsing have increased survival

-selection on offspring size

A study of hatchery-raised chinook salmon..

-Equilibrium egg mass for hatchery fish is less than that for wild fish. Selection for smaller egg size by hatchery practices?

-The more they supplement, the more dramatic effect on egg size.

Some interesting conservation implications:

What happened when hatchery ish were used to supplement natural populations???

-do not survive if egg volume is low!!

Delaying reproduction: Use energy for growth and significantly increase egg prouction

-exponential increase in fecundity with carapice width in New Zealand paddle crab.

In birds species with younger age at maturity (ducks, quail) have lower annual survival, while seabirds and albatrosses are high in both categories

r-K selection has been applied to discuss life history variation within species or between species. THey are extremes.

r-Strategist

-small

-rapid reproduction

-short-lived

-large number of offpsring

-semelparous

-unstable environments

-weak competitor

-precocial young

K

-large

-slow repreoduction

-long-lived-

-few offspring

-iteroparous

-stable environments

-good competitor

-altricial young

-genomic imprinting

-risk spreading

-phylogenetic constraints

Depends on whether allele is paternally or maternally inherited.

Less than 50 traits

-most autosomal

-critical for embryonic development

During gamete formation allele for specific gene is silenced.

Pattern of imrinting differs in males and females (erase od imprint)

eg. lgf2 (insulin-like growth factor)

-if female, both get shut off

-both heterozygous.. depends on if it came from mom or dad (whether or not expressed)

-slide 4, life histories, page 11

Mammals

IGF-2

-paternal allele expressed

-encodes hormone that stimulates cell division

CI-MPR

-encodes protein that binds IGF-2

-maternal allele expressed

tug of war: male IGF-2 max. rate of cell division (use female's resources), female CI-MPR binds to excess IGF-2 to reduce cell division

Does this happen in animals without gestation? (eg frogs, chickens).. NO

-CI-MPR binding to IGF-2 originated after placenta

-genomic imprinting also found in plants

Parental investment in male and female offspring

-expect 1:1 ratio when random mating, external fertilization and no parental care

-male and female offspring have equal chance of success

SEX DETERMINATION

genetic

-sex chromosomes

heterogametic (XY, WZ: male mammals, female birds)

homogametic (XX, WW: female mammals, male birds)

Sex determining genes

-on multiple chromosomes

Haplodiploid (haploid unfertilized.. usually male if fertilized then female)

Environmental

temperature

-turtles.. males at lower temp

-alligators.. males at higher temp

-crocodiles.. males at intermediate temp

social interaction

-higherst ranking individual is male

-if dominant male dies, femal becomes male

-sequential hermaphrodites

-protogyny (female first) : evolves when small female produces more offspring than small meales

-protandry (male first) - evolves when size/age advantage; eg. larger female produces more eggs

OFFSPRING SEX RATIO

-adjust offspring sex ratio?

red deer: higher raning femals have more male

parasitoid wasp (genetic sex determination)

-emale lays female eggs when preyhost is large

-male eggs in small prey/host

-size of prey/host is relative, based on previous encounters

-small males lose less in reproduction than small females

-largerfemale = healthier

-males make sperm.. large or small does not matter

-pathogen wants to use host to produce more pathogens

-host wants to kill pathogen

-quicker evolution in pathogen allows rapid evolutionary response:

-larger pop size

-high mutation rate

-short gen time

What is the role of the human immune system in evolution of influenza A?

3 global pandemics:

-1918 (20% world's population, 50-100 million deaths)

-1957

-1968

INFLUENZA A

8 single stranged RNA

-encode 11 proteins (polymerase, structural proteins and coat proteins)

Coat proteins

-hemagglutinin...

...initiaes infection, binds to sialic acid on host cell

...host 'remembers' hemagglutinin type, specifically antigenic sites

...mutations at antigenic sites confer advantage for virus

12 different Hemagglutinin

9 diferent Neuraminidase

How Quickly can Influenza A mutate?

-hemagglutinin genes from viruses collected from 1968-1987

-20 human years for a virus approx 4x human-chimp common ancestor!!

Found....

1)constant rate of evolution

2)most samples represent extinct side branches

-surviving lineages less diverse

WHY?

-host immune system wipes out most

-bottlenecks from human resistance and vaccines

MUTATIONS

Where did mutations occur and what type of mutation?

-nonsynonymous

-antigenic sites

Predict surviving lineages have more a.a. substitutions at antigenic sites.

-surviving 33/43 (75% more)

-extinct 31/66 (~50%)

Looked more closely...

-found 18 codons with significantly more non-synonymous substitutions... under positive selection

Can we use this information? Flu vaccines..

vaccination: infect dead virus to trigger immune system to produce antigens; later infections have quicker host response IF use the right strain of virus vaccination

Examined 18 codon positions under positive selection to see which strains survived

-9/11 predictions correct

-but can't predict next year's strain

ORIGIN OF PANDEMIC FLU STRAINS

-can the virus create new hemagglutinin and infect everyone (a super virus)?

-what if different strains recombine?

Influenza A can mutate each year to re-infect the same population (H2N1)

antigenic drift- gradual mutations resulting in subtle changes in entigenic phenotype

antigenic shift- sudden change in antigenicity resulting from recombination of the viral genome

-creates to strain of virus (H2N1 to H3N1)

nucleoprotein (WP) genes (host specificity)

-5 clades (include 2 avian)

-in each clade H closely related as are N

H2N2 and H3N2 cluster together because recombination ocurrs between hemoglutanins.

Pre 1968 human influenza no H3

-recombination of non-human straing (H3) responsible for 1968 outbreak

Does cross species transmission of viruses occur frequently?

-1918 virus resurrected from permafrost tisue

-related to contemporary swine influenza

virulence: how harmful is the pathogen?

-evolution of virulence..

-3 hypotheses including trade-off hypothesis: lower virulence allows host to survive

-determined by how much pathogen needs host to survive

Direct transmissions (cold, flu), and indirect (malaria)

-directly transmitted have much lower deaths per infection, as host must be alive..

-vector borne has much higher % deaths per transmission.

Do antiever medicines have any effect on the course of the common cold?

Takes longer to get better if you trick your body into thinking that you aren't that sick! Reduced immune response.

HIGH VIRULENCE=FAST REPRODUCTION (and use all host's resources)

LOW=SLOW

Interface of genomics and evolutionary analyses

Examines and compares entire genomes

-gene order

-# genes

-gene function

proteonomics: temporal differences in gene expression

HGT - horizontal gene transfer - lateral gene transfer

-between individuals.. not vertical transfer

Genome Size

-fruit fly 180million bp

-ameoba 670billion bp.. mostly junk

-human  billion bp.. 1.2% coding, 44$ transposable elements (genetic parasites)

Transposable elements replicate themselves... do not need a coding region

-help "move" DNA

-flanking regions (encode enzymes for moving, repetitive DNA)

Class 1 (use RNA intermediate, reverse transcriptase), and clas II, (DNA to DNA)

Retrotransposons (class I)

1..DNA of the mobile element is transcribed into RNA

2.RNA is reverse transcribed into cDNA, which then inserts into the recipient site

Conservative Transposition (class II)

-element moves from one site to another

-cut and paste

-element moves from one site to another

Replicative Transpositon (copy and paste)

0the transposable element is copied, and one copy remains at the original site while the other inserts itself at a new site

-like jumping genes with corn

-potential to duplicate large chunks

Transposons in bacteria

-mobile elements carry the transposase gene

-enzyme cuts the trasnposon from the flanking DNA and inserts it into the target DNA site

-may carry antibiotic resistance genes

-ie. ampicillin and tetracycline (can transfer resistance)

IMPACT of Transposable Elements

-can turn genes on/off through interference

If transposable elements are parasitizing the genome, how can natural selection slow the spread?

-preventing spread... eukaryotes: methylationa add methyl group)

-positive impact of transposable elemtns..

-antibiotic resistance

-exon shuffling

cuts in wrong place during transposition and large segment which contains exon is transposed

Read about shuffling.

vertical: parent to offspring

horizontal: from on species to another

-NOT hybridization

HGT results in major inconsistency in phylogenies from different genes

-evidence of HGT b/w bacteria and vertebrates (gene trees vs species tree)

-antiiotic resistance

Most foreign DNA acquired through HGT

MECHANISMS OF GENE TRANSFER..

1)transformation: uptake of dNA rom environment, potential to transmit DNA b/w distantly related organisms

2)transductionL dNA transfer by viruses

3)conjugation: plasmid transfer b/w bacterial cells

4)endosymbiosis

-multiple membranes around organelle

-4 membranes after secondary endosymbiosis

-genetic code for cl and mt dif from nuclear

-size and shape (circular)

-look at GC content

How many bacterial species are there?

-in 1988, ~3,500/1.4 million species

-in 1995, ~10 million/11million total species

What is a species and why should we care?

A species is the smallest evolutionarily independent unit.

Identify "Units of Conservation" in Natural Populations

-tuatara

-ancient reptilian lineage

-restricted to 12 island groups off New Zealand

-for conservation puroses all populations classified as belonging to one species (S. punctatus) despite earlier work suggesting multiple species

-analysis of phylogenetic relationships among individuals using allozyme (protein) loci

-3 phylogenetically distinct lineages identified

-1 previously unrecognized species restricted to single island - so special status

"Bad Taxonomy Cna Kill"

About 20 species concepts (can be used in combination)

BSC (Biological Species Concepts)

-species are groups of potentially interbreeding populations which are reproductively isolated from other such groups

-produce viable and fertile offspring

-PROBLEMS?

-asexual species (how do you know if isolated?)

-unisexual

-geographic barriers (allopatric)/intrinsic barriers

-legal definition for Endangered Species Act

MORPHOSPECIES

-based on phenotype

-limitation fossils

-no soft tissue (don't see color, etc.)

-no behaviour, song, etc

-cryptic species

PSC (phylogenetic spcies concept)

-monophyletic group composed of the smallest diagnosable cluster of individual organisms within which parental pattern of ancestry and descent

-genet rees vs species trees

-identify monophyly (based on characters used)

-no reference to reproductive isolation (benefit)

-for monophyly to occur requires no gene flow for considerable amount of time

How different do two popiulations need to be beforet hey are distinct species?

-

-can't just use a percentage

-archaea and bacteria

-transformation

-species with 16% difference in DNA sequenes can exchange genes (vs 2% in eukaryotes.. mice and humans not same species)

-gene flow can be unidirectional

Tempo of Speciation

gradualism model- morphological change is gradual.. elephants

punctuated equilibrium model- sudden bursts of speciation.. colonization/bottlenecks

How do species form?

1)populations become isolated

2)traits diverge

3)reproductive isolation

Eventually enough differences and cannot reproduce

Populations phsycially isolated (ie rivers or mountains)

-geographic isolation precedes ivergence

-reproductive isolation only observed on secondary contact

-through dispersal or vicariance

If dispersal, predict:

-closely related species found on adjacent islands

-branching events correspond to order in which islands formed,

Vicariance..

-Isthum of Panama rose ~3MYA

-did this cause gene flow to stop?

-examined 7 pairs of species.. found 3 cryptic spp

-why was the timing of the split not the same for all species????????

Shallow water spp can move until barrier complete

-deep sea spp split first

Populations are not physically isolated, but are reproductively isolated

-divergent selection (eg Killer Whales)

Mechanisms of Divergence

-What factors cause populations to diverge?

-genetic drift (bottlenecks/colonization)

-sexual selection

-natural selection

Rhagoletis fly dependent on hawthorn or apple to mate

-appls introduced to North America <300 years ago

-flies court, mate and lay eggs on/in fruit

Host Shifts

phytophagous insect Rhagoletis

-1864 found in aples

-2 host races

How did the two host races originate from a single host population?

1)natural selection through preference for food source then 2 genetically distinct groups of flies

2)flies use apples or hawthorns depending on availability then 1 population of flies

both apples and hawthorns are now found in similar areas

-examined allele frequencies at six protein loci in the two host races

-significantly different... how did this originate?

1)preference for host plant heritable

-both sexes have preference for natal host

2)mating occurs on host plant - non-random mating

-6% matings between host racs (HUGE in terms of gene flow)

-high enough to homogenize populations

-?strong natural selection?

Hawthorne fruit matures 3-4 weeks after apples and larvae experience cool period before pupating

Are there alleles that favour cool period?

-hawthorne pupae exposed to warm-cool-war cycle to mimic change of seasons

-examined adults that emerged (surviving adults only)

Changes occurred in a single generation

-hot and cold alleles were present in the population before the apple plant was introduced to North America

read about this... Speciation, page 5.

Promotes divergence because it affects gene flow directly

-drosophila silvestris and heteroneura have different heads... some males butt heads, while some stand and fight.

One Possible Scenario...

Ancestor with normal head, lek mating system, females mate with winner of competition

-mutation in 1 population, head-butting males

... lek mating system, females mate with winner of competition (head-butting)

-mutatnt allele increases to fixation, other traits develop

-leads to mals with wider spaces eyes

-ancestral population led to males with normal eyes

-in D.heteroneura, wider head = more copulations!

Tilapia

-5 forms, considered 1 species

-2 of them are near end of speciation process

-common ancestor 10kya, same breeding colouration, time and sites

-size assorative mating (small males mate with small females, and large /w large)

PREZYGOTIC

-geographic

-ecological

-temporal

-behavioural

-mechanical

-gametic incompatibility

POSTZYGOTIC
-hybrid sterility

-hybrid breakdown (reduced viability in subsequent generations)

-hybrid inviability

Gamete Recognition...

-sporophyte self-incompatibility in brassicaceae

-adhere sperm to egg in sea urchins

-egg envelope sperm, mammals

RI

-random changes

-adaptation

-selection

RI=(S-O)/N

S=matings with same species

O=matings with other species

N=total #

0=no RI

1=complete RI

Allopatric taxa will show gradual increase in RI with genetic distance.

Sympatric taxa will show extremely strong selection for high RI or will just merge back together (high RI immediately, low D, or genetic distance)

Chromosomal rearrangements

-meiotic disjunction (chromosomes not separated properly.. lead to triploid offspring)

-lower hybrid fitness

-lower recombination

Changes in mating systems

-self-incompatible>self-fertile>spp'n

-timing of reproduction

-polyploidization (change in ploidy)

Ploidy

Common in plants (70-80% plant species result of plyploidy)

Types of plyploidization:

autopolyploidy: meiotic failure in parent

allopolyploidy: hybridization

homoploidy: (sunflower).. normal hybrid infertile or low fertility. If chromosomes recombine, fertile

IE. Allopolyploidy...

Hybrid of Cabbage (2n=18) and Turnip (2n=20) is Rutabaga (2n=38).

(ie. sunflower)

-homoploidy

Genome becomes stable or fixed.

Identify blocks of parental genome.

Sections of Chromosomes non-random... natural selection

-adaptive evolution and evological divergence

co-evolution: Evolution of two or more interdependent species, each adapting to changes in the other

-i.e. predator-prey, plant-pollinator

co-speciation- parallel evolution of two associated taxa (such as a host and a symbiont), such that speciation events in the two taxa are coupled.

Co-evolution can occur from mutualism, competition,

or selfishness, but not commensalism

All other things being equal...

Partners with the

1)shortest generation time

2)sexual reproduction

3)higher levels of genetic variation

...will evolve more rapidly.

Circumpolar area of both hemispheres (wide distribution.. good chance of interaction)

>50 seabird host species (generalist parasite)

-seabird hosts found in dense and predictable colonies

-every year return to same colony

-northern hosts are gulls and penguins, southern hosts are penguins

-8 microsatellite loci

-existence of sympatric tick races specialised on each host

-ticks very remote in microsatellites... little gene flow

-would not see this pattern with high levels of gene flow

-no structure geographically

-high levels of gene flow b/w birds

-Because they are only attached for two weeks, breeding season

-birds stay local at this time

-chances of falling off onto another island is ow

-cuckoos, cowbirds

-egg mimicry

-different levels of matching

different birds reject eggs to different extents.

-cost to host parents

-cost to host offspring

-fairy wrens always abandon nests IF detect cuckoo eggs (abandon entire clutch)

-adaptive shoulder blades to push other chicks out of nest

-calls at same frequency... but same number of calls as 3 chicks. grows much faster.

-edible mimic noxious spp.

-maintained by high costs to predators and frequency dependence of mimics

-ei. swallowtail

-can't have too many non-toxic or predators won't care

-frequency dependent sel'n

Leafcutter ants

-collect leaves for mulch to feed fungus

-food fungus produces food for ant larvae, but food fungus can be attacked by microfungal parasite

-ants produce bactera on specialized body parts to make antibiotics to inhibit microfungal parasites

-antus, food fungus, microfungal parastic, and bacteria

-negative, positive, indirect interactions

Do mutations occur at a fixed rate?

-universal mt clock 2%/MY

Clocks calibrated using fossil data and geological data

-ie. rise of the Isthmus of Panama

-**asumes area colonized immediately and no subsequent gene flow

-2 spp separated 500kya and 10/500bp are different

-rate of evolution = 2%/500ky or 4%/MY

PROBLEMS

Mutation rates are not constant over time.

Small differences in rate estimates have major impact on divergence estimates

-ie. difference of 0.5%/MY

-5% divergence b/w species A and B

-1%/MY diverged 5MYA

-0.5%/MY diverged 10 MYA

What about non-coding vs coding DNA?

-control region ~20%/MY, cytb ~2%/MY (vertebrates)

-generation time?

-population size?

-taxonomic group?

BMR?

cyt b variation...

California newt 0.8%/MY

Bamboo viper 1.1%/MY

shrew 1.36%/MY

-cold blooded have slower sequence divergence than warm blooded, and large organisms are also slower.

Metabolic Rates

-low BMR, low rate of cell turnover

-high BMR, fast turnover, more replication errors

Generation time

-assumes individual's cells divide similar numbers of time during lifetime

-short generation time= more generations in sama time period than individuals with long generation time

-eg. blue whale generation time 20-25 years, mouse 10 weeks.

net divergence b/w Atlantic and Pacific clades 0.6%

-rise of isthmus 3MYA

-level of divergence 10x less than predicted

WHY?

-lower rates of evlution in turtles

-subsequent gene flow around S. America or Africa, perhaps during Pleistocene (travel beneath Africa)

RELATIVE RATES TEST

-does not require calibration point (ie. no fossil data)

-branch lengths are additive

In the last 570 million years, as many as 20 mass extinctions.

-end of Ordovician, Devonian, Permian, Triassic, and Cretaceous

-big five responsiblefor 4% of all extinctions

-over 50% of families extinct in Permian

The larger the geographic range, the lower the extinction rate, and the higher % chance of survival

ORDOVICIAN (440 MYA)

-jawless fish, plants and terrestrial arthropods present

-marine invertebrates: 22% families and 60% genera extinct

-glacialmaximum exposed sea sheles and flooding of shelves with freshwater from melting.

PERMIAN (250mya)

-llarget... 49% marine animal families, 63% terrestrial organisms

-Pangea formed at that time

-ocean cirulation poor.... low oxygen in water

-deep water enriched with methane and hydrogen sulfide

-as ocean currents started again, released large amounts of CO2 into atmosphere

-volcanic activity in eastern Russia (area the size of Gulf of Mexico)

-all of this resulted in increased temp of 6C

-took about 100MY for biodiversity at family level to return to pre-extinction levels.

CRETACEOUS (65mya)

-50% of extant genera became extinct

-invertebrates affected

-dinosaurs already declining

-large scale fires

-soot deposits several cm thick

-seed plants survived suggesting major fires were short lived (ie. dormant seeds)

-meteor impact.. Yucatan Peninsula

-may predate extinction by 300ky

-ejected debris into atmosphere, tsunamis, fires

meteor 10-15 km wide

-high levels of iridium found in meteors

-180km wide crater

-ocean floor where meteor hit had large amounts of anhydrite (CaSO4)

-vaporized releasing SO2 and water (H2SO4)

-acid rain and global cooling (particles scatter light)

-extinctions occurred up to 500ky after impact

Following mass extinctions, 'direction' of evolution changed

-end of Permian.. radiation of amniotes

-end of Cretaceous... mammal radiation

OTHER CATASTROPHIES

Volcanoes..

Krakatoa (indonesia) 1883

-tsunamis in Japan and west coast of N America

-Cascade and Sierra Nevada Mountains

-ash 2000km away in Nebraska burying herds of woolly rhinos

-1815 another Indonesian volcano (global temp decreased 3C)

-glacial dams.. Lake Missoula formed by arm of Colubia ice field

-tsunamis.. 1964 Alaska earthquake.. waves destroyed structures 200m above sea level.

BURGESS SHALE

-formed 520-515 mya when plate hit west coast of North America

-AB/BC border was west coast

-shallow sea floor pushed above sea level and covered by mudslide

-some organisms look like etant species, but many extinct lineages

-most invertebrates and some algae

Opabinia regalis

7cm long, feeding appendage, segmented, 5 eyes

non-random distribution of organisms

-continental regions have relatively uniform distribution of plants and animals

-organisms in some parts of the globe (ie. South America ad Australia) were much more unusual than others (ie. N. America and Eurasia share many similar species)

-animals of given continents were related to each other more closely than they were to elements from the biotas of other continent

-similar regions defined on the distributions of plants, soil type, and climate

endemics- groups found only in one particular region

-73% mammalian families endemic to one faunal regions

-six faunal regions (plus oceana.. islands)

-look at these in text.. cannot read off slide

-usually less than half are endemic

-continental drift

-mountain building

-alter physical barriers

-glaciations

in Jurassic first birds, and gymnosperms start to dominate (150mya)

-pangea in permian

130spp Chameleons

-did they speciate as Gondwana broke up?

Hypothesis: If chameleons speciated as supercontinent broke up, order of speciation should correspond to order of break up

-is allopatric speciation, but not vicariance!!

-no single group in any clade

-therefore dispersal

RATITE BIRDS

-originated on southern supercontinent

-vicariance event

-evolved in isolation through genetic drift, mutation and selection

KEEP IN MIND>>...

Organisms can spread out from their centre of evolutionary origin even if the continents are not connected, but limited by

-the diserpsal capacities oft he organisms themselves (some fly, others walk)

-the extent and types of barriers in their way

-time

-climate

AND>>>..

Organisms can go extinct even in areas where they originated

-eg. camels evolved N.America

-no longer found here

distribution is a dynamic phenomenon, changing through time - glacial events - everything new in recolonization

Continents were not always in current configuration and clmate has changed.

It is amazing that many aspects of distribution still bear the marks of ancient lineage originations and continents given the amount of time that has passed

ISTHMUS OF PANAMA

-South Merican species evolved in isolation for ~135my

-species affectd differntly

-filter routes

GREAT AMERICAN INTERCHANGE

-late Miocene (6-7mya) isthmus was a series of islands

-second group dispersed after land bridge formed (2-5mya)

-dispersal equal at first, but later increased dispersal into South America

GLACIATION

-Pleistocene 2-8mya

-3 main sheets

-innuitian (north)

-cordilleran (west)

-laurentide (east)

-land bridges

-sea levels

BERINGIA

-large refugium in North Pacific

-connected Nearctic and Palearctic

-cold-adapted species, but warmer than today with cold temperate climate

-major source of colonists

REFUGIA

-multiple refugia

-Beringia

-nunataks (mountain tops)

-coastal refugia.. NW coast, eastern

-large southern refugium

-driftless refugium

phylogeography- combines fossil data current distribution, geology, and DNA to reconstruct the biogeographic history of organisms

nuclear markers:

-autosomal: biparental

-X chromosome: uniparental but essentially biparental

-Y chromosome: paternal

organellar markets: uniparental

-mtDNA maternal

-cpDNA maternal in angiosperms, paternal in gymnosperms

-In Chihuahua Spruce, mtDNA is very localized, as cones don't move around much, but cpDNA is different everywhere

Two species, Townsend's warbler and Hermit warbler.. can produce a T-H hybrid.

Hermit lives along coast, Townsends more inland and North

20,000 ya populations were isolated

8kya T-warbler dispersed

5kya T warblers arrived on the coast where H were established

-complex interactions:

-HEWA breed earlier than TOWA

-mals arrive before females

-male TOWA and HEWA compete for females

-TOWA out compete HEWA and breed with HEWA females (think about mtDNA)

TOWA femals were not able to reproduce in some areas, but were in others

-homo originated ~4-5MYA

-H. sapiens ~500kya

African rain forests started to dry up 5-6MYA

-small population east of Great Rift Valley isolated

-occurpid grassland/savannah

-diverged in allopatry from lineage leading to chimpanzees

Hominid Lineages

-evolutionary relationship uncertain

-multiple overlapping lineages

-We know the species tree for gorilla/chimp/human, yet the gene tree does not alawys match

-however, 11/14 loci showed chimp and human to be closest (which is true)

** multiple groups of homo existed!!! and other linages

Based on cranial and dental traits of humans, apeas, and fossil hominids

Multiple lineages present at same time

Phylogeny based on characters questionable, timing of fossils is NOT

RECENT HOMINIDS

H. heidelbergensis

H. neanderthalensis (Europe)

H. erectus (Asia)

H. ergaster (Africa)

aleoanthropologists split on taxonomic status

-cannot know origins

Prior to H. ergaster and H. erectus all hominids in Africa

-H. sapiens appear in fossil record ~100kya

-two current hypotheses for human origins

-out of Africa: originated in Africa and spread

-two independent origins (African and Asia) and hybridized

current evidence supprts 1st hyp.

modern human tree common ancestor ~ 170,000 ya

IF out of Africa hypothesis is correct,

-single, recent exodus of H sapiens (100-200 kya) completely replacing all other hominids

-earlier exodus contributed no DNA to modern humans

-predict little genetic differences among ethnic groups, higher variation in Africans

Little divergence amongst modern humans, which suggests we are a young species.

-gorillas have high divergence, as they are an old species

Reached new world around 7-20 kya

Approaches...

mtDNA (mitochondrial Eve.. last female common ancestor).. 140-200kya

Y chromosome (common male ancestor.. 60-80kya)

-times are different

-difference due to when lineages went extinct

MITOCHONDRIAL EVE

-recall that some lineages become extinct

-does not mean single female present

-does mean that all modern individuals descended from common female

One disproportionately common Y chromosome haplotype

TMRCA (time to most recent common ancestor) 1000 years ago in Mongolia

Genghis Khan!

-hordes of soldiers kill men and rape women.. leave haplotype

Marie Antoinette

Jesse James

Romanovs

Ice Man

Ice Maiden

most collected from hair samples