-are loci on the same chromosome

-they are inherited as a package

-fewer map units separating them means less recombination (closer they are, the more likely they stay together)

linkage equilibrium: loci are in linkage equilibrium when the genotype at one locus is independent of the genotype at a second locus

-if A+a are 2 alleles for a locus, it is indepenent of whether it combines with allele B or b at a different locus

linkage disequilibrium: loci in linkage disequilibrium means a non-random association between genotype at one locus and of genotype at a second locus

-genotype at locus A affects genotype at locus B

What is the difference between the distribution of alleles in linkage equilibrium and linkage disequilibrium?

**allele frequencies are exactly the same

-haplotypes or 'chromosome frequencies'?

haplotype: haploid genotype (ie gametes, organellar genome)

D = coefficient of linkage disequilibrium

D=g_ABg_ab - g_Abg_aB

(difference in genotype frequencies)

When D=0, loci are not linked.

-max D = 0.25

LOCI ARE IN EQUILIBRIUM IF (one of three ways):

1)frequncy of B on chromosomes with A= frequency of B on chromosomes with a

2)frequency of AB=frequncy of A times frequency of B

3)D=0

-BA=

-selection on multilocus genotype

-genetic drift

-population admixture

SELECTION

-A nad B are growth factor genes

-individuals with less than 3 dominant alleles die

-find allele frequencies, then use one of the three criteria to see if linked!

GENETIC DRIFT
-finite population

-locus A fixed

-2 haplotypes (AB, Ab)

-mutation on chromosome with Ab

-4 possible halplotypes (AB,Ab,aB,ab)

-aB not observed

POPULATION ADMIXTURE

-this is the Wahlund effect

-2 populations with different frequencies that are both in linkage equilibrium combine

-afterwards they are in linkage disequilibrium

Rate of decrease in D is proportional to the rate of recombination (r)

-max r is 0.5 (rate for independent assortment... 50/50 chance parent passes on)

-when r = 0 genes are completely linked, D=0.25

-the higher r is, the faster D decreases (moves towards linked equilibrium)

**look at Feb1/p5/s2**

1)Reconstruct Gene/Allele History

Gaucher disease

-mutation in GBA gene

-enlarged spleen, anemia, fragile bones

-1/19 Ashkenazi jews are carriers

---N370S allele, also found in other population (370th a.a., not unique))

---84GG allele (extra a.a. guanine), unique to Ashkenazim (want to trace history of this!)

-identified marker linked to GBA on chromosome 1

-D1S305: microsatellite

---allele with 8 repeats found in 59% individuals with 84GG compared with 24% GBA+

Origin Linkage?

-DRIFT!

-estimate time to most recent common ancestor (TMRCA) 1.3kya

-other disease-causing alleles in Ashkenazim population

---ie. Tay-Sachs, Fanconi anemia

-TMRCA: 3 groups... 400/1.5/3 kya

-dates broadly consistent with population history and series of founder effects

-left the middle east 2-3 kya

-arrived in central Europe 1-1.5 kya

-arrival in Lithuania (recently)

2) POSITIVE SELECTION

-favour advantageous mutation

-G6PD on X chromosome

---100s of alleles, most decrease enzyme's efficiency

---varying effects (severe.. hemolytic anemia which bursts RBC)..(allele 202A, possible malarial resistance)

-18% in 3 African populations

-230 males, 9 alleles, with 11 point mutations

**strong correlation b/w frequency of G6DP deficient males and malarial endemic regions

If G6PD-202A is under positive selection, what owuld the distribution look like?

-If mutation is neutral and on single locus, three possible fates

-over time... drift... linkage equilibrium with other loci

OTHER EXAMPLES OF RECENT POSITIVE SELECTION

-sperm motility and fertilization

-carbohydrate metabolism

-olfaction

-lactase

Population Mutation-drift Equilibrium:

-young, rare alleles: high linkage disequilibrium

-old,rare alleles: low linkage disequilibrium

-old, common alleles: low linkage disequilibirum

Asexual

Unisexual

Sexual

Asexual/Sexual

ADVANTAGES

-no searching for mate

-clonal reproduction

-decreased rate predation adn competition in mating

-allocation of resources

DISADVANTAGES

-no recombination

-decreased genetic variation in population

-increased mutations (cannot be removed)

..there are 3 modes...

Parthenogenesis

-most common... asexual cloning

Gynogenesis

-Male sperm interacts with egg, trigers development, but does not fertilize

-male genetic material not in zygote

-goldfish/guppies

Hybridogenesis

-different species "mates" with female

-genetic material is incorporated, but is not passed on... only female information passed on

**divergence is 2%/million years b/w unisexual and closest relative

***nucleotide diversity (amount variation) increases in sexuals along with sequence divergence.. but this is not the case with unisexuals

Smith studied populations like aphids, which are able to choose b/w asexual and sexual

-a population will have asexual and sexual reproduction if both

1)produce the same number of offspring

2)sets of offspring have same probability of survival

Assumption 1

-if equal number f ofspring for sexual and asexual, the number of asexual individuals will increase

-this is a two-fold cost of sex

Assumption 2

-offspring survival for sexuals is greater than asexual if selection exists

-sexuals able to create new combinations of alleles

***Recombination acceerates the rate of evolution

-creats beneficial mutations with different origins

-asexual must wait for mutation.... takes longer to occur

Muller's Ratchet

-overall number of deleterious alleles in a finite, asexualpopulation can only increase over time

-rate of reverse mutations is very low

-genetic load increases

Short-term advantages of sex:

-decrease deleterious mutations

-rapid environmental change

-recombination

"It takes all the runnng you can do to stay in the same place"

-frequency dependent selection

-parasite (P) adapts to most common host (H) type

-rare host type advantageous

*As H2 becomes more common, there is selection to increase the requency of P2, which in turn selects against H2, and H1 increases in frequency.

*Plotted against time, the frequency of ach genotype will oscillate

*always a trade-off! Cannot be resistant to everything!

EX

-two common snail clones are infected by trematode which sterilizes male snailes

-cycles of success of each are temporally distinct

-life histories

-sexual selection

-kin selection

-quantitative genetics

-speciation

-biogeography

Mendelian (autosomal loci)

-allozymes (proteins) - low levels variation (looking at protein)

-microsatellites - neutral.. don't normally encode

Uniparental

1)organellar DNA (no repair mechanisms... mtDNA/cpDNA

-usually higher mutation rate

2)some sex chromosomes (ie Y chromosome)

-short tandem repeats (ie. AC)

-highly variable (during replication, can have different number of repeats)

-bi parentally inherited

-neutral (no effect)

-cannot trace allele to ancestry

-cannot be used to draw phylogenetic trees

-this because mutations may gain and loose repeats

-group specific

-can be used to infer who the father is not, and who the father could be

-if at a single locus, offspring has two microsatellites, and mother is known... the one that doesn't match is the one the father gave.

-inclusive fitness

-shared DNA

-depending on how far from starvation, the same amount of food might give donor 6 hours of life, while the same amount would give the recipient (closer to death) 16 hours.

heat DNA - single strand

-re anneals at different rates dependent on copy number

-highly repetitive DNA will anneal quickly (many possible compliments)

homoduplex- 2 strands DNA with similar origins (same species)

heteroduplex - double stranded molecule formed with one strand from spp A and one strand spp B

Look at melting curves of DNA which show %ssDNA dissociation versus temperatue of diferent variable (ie. emu emu vs ostrich emu vs chk emu, etc)

-Shape of curve is indication of how closely related species are

-the higher the temp at dissociation, the longer it takes, the more relatd the species are.

-99.9% maternally inherited

-Rice mitochondrial genome is 491kb (almost 1/2 million bp)

-human is 16.5 kb

-use PCR or restriction digest

-many genes in same molecule that mutate at the same rate (ie. 20% in 1 million years)

Polymerase chain reaction

-need only a small amount of DNA

-can pull off leg from dead fruit fly

-easier than using allozymes... can use minimally invasive techniques and dead tissues

-use polymerase from hotsprings bacteria, as it is stable at very high temperatures

-basically photocopying DNA.. copy b/w primers

-heat to 94C, get s, derease to 50 so primer can bind to DNA

-double amnt DNA each round

similar technique to PCR

-instead 2 primers, use 1

-end pu with lots of copies of many sizes

-can then go through and read sequence

-phloem-feeding insects (aphids)

-reduced genome (bacteria.. helps aphids.. only 100 genes)

-plasmids of a.a. biosynthesis (in bacteria, used by aphid)

bacteria makes..

trpEG (rate limiting gene)

leucine

-both increase host's ability to synthesize a.a. 16-20 times

**every host speciation event results in a bacterial speciation event

*not just 1 locus of gene, but entire genome

Compare genomes of different species

-evolution (phylogeny)

-gene function

-disease

Compare..

-gene order (clustered? order? scattered?

-structure

-characters (splicing, codon usage)

-how much DNA between species is unique? how much is conserved?

-99%GENE SIMILARITY between human and mouse (not DNA sequence)

23 vs 20 chromosomes... all in difference areas

-sequence diversion only about 75%

-do different organisms/different cells express the same genes?

-start with mRNA (not tRNA)

-mRNA and reverse transcribe

-only want DNA that is expressed

-bias... not every is as easily transcribed

-put ss cDNA in microchip

-it has tonnes of genes

-cDNA binds to compliments

-expressimng some of same genes.. intermediate colors

-some expressing none

-some none

-some both

***reverse transcription is not perfect!!

-microsatellites

-DNA-DNA hybridization

-mitochondrial DNA

-PCR

-Sequencing

-Comparative genomics

-microarray

definition: Molecular markers are found at specific locations of the genome. They are used to 'flag' the position of a particular gene or the inheritance of a particular characteristic.

-continuous distribution, not discrete (ie. height)

-genotype at multiple loci and environment

East examined 454 F2 plants, did not observe parental phenotype

-by 5th generatin had range of parental phenotypes

-used tobacco.. crosed two lengths... got an intermediate length.

-selected for short and long from intermediate offspring, and got parents back

*crossing an RR with an rr will yield a 1:2:1 genotype distribution

-this is with one gene, gets WAY more complicated with 3 genes

-as you add more loci, you increase the number of possible phenotypes

QTL- quantitative trait loci

-loci responsible for height in humans, colour in wheat, etc

QTL mapping is physically locating the genes

Get markers throughout genome

Look for candidate loci linked to markers (microsatellites, etc.. non-coding.. linked with QTL gene)

Use known location of marker to sequency candidate locus

Transmission disequilibrium test

Is there are correlation with mutation/allele at candidate locus and trait?

NO = candidate locus is not QTL

YES= how many individuals with specific mutation/allele have that trait? All individuals with that speciic mutation/allele must have that trait, but not all individuals with that trait may have that mutation/allele (ie. multiple loci encode the trait)

M. cardinalis and M. lewisii hybridized in lab

M.c pollinated by hummingbird (red, long tube)

-M.l pollinated by bee (need landing pad).. poor eyesight

What genes are responsible for differences in floral traits? How many genes? Different effects?

TWO SCHOOLS OF THOUGHT

Fisher: alleles driven to fixation by natural selection have subtle effect on phenotype

(most believe this)

Orr: some of the fixed alleles have large phenotypic effects

Used QTLs to determine what the effects were of different genes

-took parental species.. F1 hybrids selfed.. F2

-many many types of F2 hybrids... huge range

-screened 66 marker loci fixed in each species

-markers randomly distributed throughout genome

-if QTL and marker linked.. linkage disequilibrium (see correlation b/w trait and allele)

-if unlinked, linkage equilibrium (no correlation)

-association /w marker genotype and individual's phenotype

-If M (marker) and Q (candidate gene) linked, what would F1 look like?

-What if M and Q are not linked?

In F2, if marker is linked to a QTL, phenotype will vary with marker presence/absence

-If marker is not linked, phenotype will remain the same regardless of marker

-This example supports Orr's view

-Changing single allele at single locus makes M.lewisii 70 times more attractive to hummingbirds, and only 6 times less attractive to bees

Once marker locus identified, we need to find a QTL gene

-testing candidate loci...

Cronhn's disease

-range of severity

-runs in families.. likely hereditary

-recent increase: environmental factors?

-exposure to bacterial pathogens, decreased intestinal parasites?

-candidate gene on chromosome 16

-NOD2: bacterial immune response

-found insertion> frameshift in 3 people with Crohn's disease

-does the 3020insC allele increase risk of Crohn's disease?

-caused premature termination

Transmission Disequilibrium test

-does patient (2,3) have parent (1,4) who carries 3020insC allele?

-if NOD2 mutation is associated with Crohn's disease, predict..?

-39/56 showed expected result (significant)

1)heritabiilty of variation

2)fitness

-to predict response to selection

7 clones of Yarrow from Mather population transplanted at 3 altitudes

-measured after 3 years

-higher altitudes = shorter plants

STEP 1

Trait measured as deviation from the population mean

Phenotypic variation (P) can be influenced by environment and genotype/allele frequencies: P=G+E

broad sense heritability (h) measures how much of the phenotypic variation at the population level is caused by genetics h=G/P=(D+A)/P

narrow sense heritability (h²)

h2 = A/P = A/(E+A+D)

-plot points of mean offspring phenotypic values vs midparent values and see how much they vary from a slope of 1 (100% heritability)

Genetic Variation = additive variation + dominant variation

VG=VA+VD

-when no dominance, VD= zero

When dominance, VD=dominance factor, which is the total difference between the points and the line of best fit.

Additive Genetic Variation (A): effect of combination of alleles at various genes

h2=A/P (narrow sense heritability)

-fraction of the total phenotypic variation in a trait accounted for by additive genetic variance

-measures potential response to selection

Why can't we just measure heritability by measuring parents and offspring?

-Because there is an environmental component.

STEP 2

strength of selection (S)

Difference b/w mean of selected individuals and mean of the entire population

Selected for mice with long tails... increased 10%.. extra vertebrae

S=t*-t= average of selected individuals - population average

STEP 3

-quantify heritability and the effects of selection

-predict evolutionary response (R)

R=h2S

R=O*-O) (midoffspring dif.)

S=(P*-P) (midparent dif.)

S varies with conditions!

-if heritability (h2) for beak depth is 0.79 before drought, and beak depth becomes 4% larger after drought (R), selection differential (S) = 0.04/0.79 = +5%

skypilot (alpine flower... diameter is 12% larger at high elevations)

-bumblebee is sole pollinator at high elevations

How can it be bigger at high elevations?

Though increased elevation, bumblebees are only pollinators, while other pollinators are not present.

Measured flowers and seed set

Collected seed, planted offspring in cage

P=14.2mm (flower size)

Selection differential (5%).. 5% larger than average

-difference b/w bee pollinated and non-bee pollinated flowers

R=0.01-0.05, depending on h2 (low 0.2 or high 1)

-small or large response to selection

-expect offspring with bigger flowers

-this R value seems small, but looking only at 1 generation!

Snakes..

escape can be straight or random (back and forth)

pattern can be striped or spotted

Trade-offs!

stripes with lots of reversals has very low fitness... spots with reversals has high fitness...

-stripes with no reversals has high fitness, spots with no reversals has average fitness

Juvenile garter snakes

adaptation

Only natural seletion can produce adaptation.

Def: Trait(s) that increase the individual fitness.

Oxpeckers believed to reduce  of ticks on cattle

Spend 85% of time grooming cattle, probing in ear.

Exclusion Experiment

-Control group:birds

-Experimental group: birds excluded

Concluded expeckers eat earwax and blood, but cattle are not the native hosts for oxpeckers

Experimental

Observational

Comparative

When studying adaptations....

-differences among population/spp are not always adaptive, may be mutation and drift

-not every trait is an adaptation

-adaptations are compromises

Threat display by tephritid fly appears similar tot he jumping spider

Hypotheses:

1)flies to no mimic jumping spider

2)flies mimic spider to deter non-spider predators

3)flies mimic spider to deter predation by spiders

Predictions:

1) no mimicry... all predators will attack fly

2)mimicry deters other predators ... banded wings will deter other predators only

3)mimicry will deter spiders

Can reject 1 and 2. Fail to reject 3.

-thermoregulation in garter snakes

CT=critical temperature

Do garter snakes randomly select rocks for night time retreat? How are rocks selecteed?

Given equal numbers of thin, medium and thick rocks... snakes those medium rocks

Thin rocks release heat too quickly

Thick rocks won't get as hot.

Can evolve and be adaptive if increased fitness accompanies change in phenotype

Interaction among genotype, phenotype, environment

reaction norm: how genotypes change in phenotype across a range of conditions

VERTICAL MIGRATION IN DAPHNIA

-mainly asexual clones.. measured phototactic response

-10 daphnia per column

-10 genotypes from each of 3 lakes in "fish free" water and water from lakes with fish.

-water constant... daphnia from different lakes.

From lakes with more fish... go down.

From lakes with no fish... go up.

Can phenotypic plasticity evolve?

Why is there more plasticity at the fish-heavy lake than other lakes?

Daphnia resting eggs from sediment cores in an artificial lake with a stocking program

-measured response of Daphnia to chemicals produced by fish.

.... plasticity yes... but non-directional

-with many fish it is directional

Horn size and survival of offspring (higher survival from bigger horned sheep)... but big horns are targeted by hunters...

"Decline of the fittest"

Flower number and size...

Why do male and female flowers have a similar appearance?

1)for female flowers to attract bees (with pollen)

-stabilizing selection male and female flower similar size

2)female flowers resemble male flowers most frequently visited by bees?

-directional selected for larger flowers

Found that bees prefer larger flowers, so why aren't female flowers larger than the male flowers

A trade-off exists between flower size and number of flowers per inflorescence

For flowers, more is better, but if small display has to still attract bees...

CONSTRAINTS...

-suchsiapollinated by hummingbird... different colors!!  flower color changes to indicate when hummingbird shold come (when it is nectar producing)???

Is it a pollinator cue?? NO!

-red attracts hummingbirds to flower to pollinate receptive, green flowers?? no...

Physiological constraint?? YES!

-pollen germination and tube develoment

-from day 1 to day 4, 0-100% of tubes reach ovary

Species existed along branches, not just at the tips

Traits can be derived (not in common ancestor) or ancestral

Closely relatd species have similar traits

More than one way to draw a tree!

DIFFERENT WAYS TO DRAW

network-complicated ... look at drawing

Bifurcating- traditional mobile style

# of possible trees increases exponentially with # OTU (operational taxable units)

4....15

8....>10000

100.....2x10¹⁸²

Not uncommon to have 100... look at data.. which trees are more likely?

homologous trait: descent from common ancestor (vs analogue)

synapomorphy: shared derived trait

-originate as a node

-used to identify related groups

-nested

-needed to build tree

steps...

1)select characters and outgroup

2)construct matric

3)build tree

Identify synapomorphies...

-what is the direction of change?

-ancestral or derived?

-how do we know what character state was in the common ancestor? (fossil record/outgroup analysis)

outgroup: closely related to "ingroup" but diverged before any ingroup taxa

Outgroup Analysis

-traits present in outgroup and all of ingroup: is it ancestral/derived unknown

-traits present in outgroup and some of ingroup: is it ancestral/derived unknown

-traits present in some of ingroup and absent in outgroup: is it ancestral/derived/uknown

-traits present in outgroup, absend in ingroup (or vice versa): is it ancestral/derived/unknown

can use morphology or DNA... then calculate distances between characters..

Steps for tree building:

1)characters

2)matrix

3)tree

Unweighted pairwise group method with arithmetic average

1)estimate all pairwise distances

2)take smallest distance d_AB=0.08, connect d_OB=d_OB=0.04

3)next smallest distance d_DE=0.12

*This is using hypothetical genetic distance for five observational taxable units

*extant species (tips) are zero!

4)Now we need to connect OTU (B) that is already in a clade!

5)Finally, connect all clades

d=average d_AD,d_BD,d_CD,d_AE,d_BE, and d_CE

**Assumes all rates of evolution are equal

The simplest explanation is almost always the right one.

-smallest number of changes (fewest steps)

Alternative methods...

1)Maximum likelihood

-probability approach, what is the probability of observing data under different models of evolution?

-computationally VERY slow

2)Bayesian inferenes

-local vs global peaks

-heavy math

-gives probability of trees

-highest probability is the highest peak

MOST PARSIMONIOUS TREE

Parsimony score: number of character changes (mutations) along the evolutionary tree

-the most parsimonious tree is the one with the smallest parsimony score

-involves creating a new data set by sampling N characters randomly with replacement

-resulting data set is the same size

-some cahracters have been left out and others are duplicated

-one way to determine confidence in the tree

-have many data sets exactly the same size...

-use consensus tree

monophyletic = both clades contain all the closest relatives

polyphyletic- neither clade contains all the closest relatives

paraphyletic- one clade contains all the closest relatives, but the other does not.

-in the perfect world, gene tree = species tree

-if looking at traits, must look at homologous traits!!!!!!!!!

Keys to Trees:

-use several appraoches

-bootstrapping

-include outgroup to root tree

-often deep splits wil be the same b/w methods and have high bootstrap support, but the tips of the branches will change

Why are conspicuous traits restricted to one sex?

How could evolution by natural selection account or such traits?

Why do traits that appear to be energetically costly and make individuals more vulnerable to predation exist?

ecological selection-differnetial reprouctive success due to individual variation in survival and reproductive output (excluding mating success)

sexual selection: differential reproductive success due to individual variation in mating success

-does one phenotype have higher mating success than another?

Sexual selection, like other forms of selection, involves non-random reproductive success, and acts on both individuals and gametes

intrasexual: contests b/w members of the same sex, usually male-male competition

intersexual: selection via mate choice, usually non-radom mate choice by females

Parental investment

-gamete production (energy required)

-parental care

Limits on Reproductive success

Mating Systems

-monogamous?

-promiscuous?

etc

Operational Sex Ratio

-more males or females mating?

**different costs for males and females

"sperm is cheap"

-rates of reproducton in Drosophila..

-number of offspring increases linearly with number of mates for males, but levels off for females...

-females are limited by access to resources and by time

Bateman's principle:

-male reproductive success is limited by access to females

-female reproductive success is limited by access to resources

-can lead to a conflict between the sexes, with females being the choosy sex

Parental investment increases offspring survival, but at cost to parents' future reproductive success

-differs among species

-usually birds have biparental care and monogamous mating system

-usually mammals have uniparental female care and polygynous mating system

-usually fish have uniparental male care and promiscuous mating system

EPY and Parental Care

-the more EPY in brood, the less investment seen by the father bird

-this is not shown by the mother.. as mother has equal amounts of genetic material in all offspring

Mating systems:

-monogamy

-polygyny (male promiscuity)

-polyandry (female promiscuity)

**sexual selection is most intense when there are many mates (promiscuity) and less intense when monogame (everyone gets a mate)

In rough skinned newt, there is no parental care, yet females astill seem to be choosy.

In pipfish, paternal care is exemplified, and a reversal of bateman's rule is observed

Intrasexual selection...

-direct competition

-sperm competition

-infanticide

Intersexual competition

-female choice

Competition b/w males has led to extreme sexual dimorphism when males can potentially control large harems.

Strong relationships exist b/w fighting succes and reproductive success in elephant seals

Many species have polymorphic male mating strategies.

sneakers: males not directly engaging in competition for mates may gain extra pair copulations

-ie Jack salmon

female mimicry: one way to distract or interrupt a competitor

direct benefits: females may benefit from increased nutrition, provisioning, or paternal care that increases their reproductive output or the quality of their offspring.

indirect benefits:

good genes hypothesis: genetically superior mates produce offspring with higher fitness

sexy son hypothesis: females mating with prefered fathers produce sons with higher mating success

A form of direct benefit!

-Male hanging flies present partners with insect food items

-females prefer bigger food items

-size of the gift correlated with the duration of copulation and the number of sperm transferred

Many female insects gain direct benefits by consuming a portion of the spermatophore presenting to them by males (consumption of sperm packets)

Sexual Cannibalism

-nuptial gifts taken to the extreme

-Male australian red-backed spider performs "somersault" into mouth of female!

-female eats male after they mate

-injects sperm and jumps into mouth

-fertilizing more and more while she eats him (his parts still inside)

-fertilizes more eggs during consumption

-females who consume their mates are less receptive to 2nd mating

-nutrients from male boost egg production

-chance of finding another mate is low (one big chance for male)

-indirect benefit

Frogs... females discriminate most strongly against short calls...

-rate or volume don't affect female response... just duration

-long call = good genes?

-looked at fitness of offspring with short and long call males

-larval growth, survival, and time to metamorphosis are al better for long call frogs

-found either no difference in some cases, and long call advantage in some cases (never short call advantage)

Molecule from class 1 and class 2 combine to produce antigen (more antigens = stronger immune system)

-humans average 6 class 1 alleles, and 8 class 2 alleles

-choost mate to maximize antigen diversity in offspring

-sticklenacks have 2-8 MHC class two

-offspring with 5-7 allels have lower parasite (tapeworm) loads

-females spend more time with males with many MHC (6-8) alleles

Want to produce desirable offspring!

IF variaiton in eyestalks and preferences should lead to assortative mating..

Assortative mating should produce genetic correlations b/w sons anddaughters within families...

-daughters preference is correlated with son's eyestalk length (brother and sister)

Selection on male eyestalks should produce a response in female preference (daughter's preference correlated with father's eyestalk length)

If trait and preference is heritable..... runaway selection.

**By selecting for certain length, also selecting for female preference of that length..

-when short eyestalks were selected, females preferred short, and vice versa

In seals (harbor/elephant/etc)... meanharem size is correlated with sexual dimorphism.

-In more monogamous systems, males and females are roughly the same size

Is female choice resonsible for producing sexual dimorphism in barn swallows?

*experiments showed that mating success was correlated with tail length**

-used unaltered, tail cut, tail elongated, and tail cut and reattached

*females invested more resources in perceived longer tails.

-longer tails were only ones to gain EPC

-female only cheated on shortened and controls (only faithful to lengthened)

-elongated has most # fledgings and more proportion second copulations

*females invested more resources in perceived longer tails

-shortened took longest to find mate!! shortened breeding season... no second clutch.

-male parental care increases male investment in ofspring production

-male giant water bugs guard eggs

-male Dendrobatid frogs carry tadpoles

SEXUAL SELECTION ON FEMALES
-polyandry!

-Gunnison's prairie dog

-the more partners the mother has, the larger the litter size at first juvenile emergence

-stronger sexual selection on females leads to the expression of secondary sexual characters in females as opposed to males

-leads to Bateman's reversal (pipefish) where females produce more offspring with more # of mates.

Male and female orchid flowers originally described as 2 species

-access to pollinators restricts reproductive success

WILD RADISH

-single coour gene W=white, w=yellow

???? look at slides

Kin selection occurs when natural selection favours the spread of alleles that increase the indirect fitness.

inclusive fitness: direct and indirect fitness

-what if selfless act by donor increases fitness of its kin?

Hamilton's rule: allele for altruistic behaviour will spread if:

1)r>C/B, were r=relatedness, C=costs, B=benefits

2)coefficient of relatedness (r)=probability that homologous alleles in two individuals are identical by descent (similar to inbreeding coefficient)

r for half siblings = 1/4

r for full siblings = 1/2 (1/4 shared through mother and 1/4 shared through father)

r for first cousins = 1/8

Co-operatinon/mutualism = yes

selfishness = yes

spite = no

altruism = ?(yes and no)

-use alarm calling

-two types: whistles (avian predators) and trills (mammals)

*females whistle more than males!

Offspring help raise next generation

-in animals occurs when resources limited

Colonial 40-450 individuals/colony with subgroups in colony

-nonbreeders pair with members of the group

-all nonbreeders help raise young in subgroup

-who do the helpers help?

Probability of helping is WAY higher in natal nonbreeders

-more related, more likely to help

Need to be able to recognize kin, but how?

-phenotype matching: imprint on parent's traits

-recognition genes: eg. major histocompatability complex (MHC) produce odor cues

Belding's ground squirrel.. individuals reared apart.

-Sibling pairs are less aggressive.

armpit effect - learn what you smell like and others with a similar smell are relatives

Example of kin selection

Environment and Cannibalistic Development in the Tiger Salamander

The effect of genetic relatedness on the development of cannibal forms of the tiger salamander in aquaria with equal larval densities.

Rates of cannibalism increase as the proportion of nonsiblings present increases.

SPADEFOOT TOAD
-siblings of discriminating cannibals 2x as likely to survive (B=2), cost to discriminating cannibal almost zero.

Hamilton's rule... at what level of relatedness does this work??

Example of kin selection

-wood mice

-promiscuous

-sperm competition..

-sperm trains 2x faster than single sperm

-break up to fertilize egg... some sperm "die"

Increase costs incurred from non-kin

coots

-50% chicks/nest die

-varation in egg colour

-females can disriminate eggs

-what happens to female's offspring when other females lay eggs in nest

When female cannot discriminate, more parasitic eggs... and fewer of own.

recall Hamilton's rule: frequency of altruistic allele increases if r>C/B

greenbeard effect: allele frequency increases because individuals favour others with allele

-in theory.. the greenbeard allele

-produces a greenbeard

-ability to recognize greenbeard

-discriminate based on presence/absence of greenbeard

-individuals are not related, but have the same allele.

When slime mold amoebae aggregate to make fruiting bodies, the cells that form the stalk sacrifice themselves on behalf of the cells that form spores

csA protein on cell surface, sticks to other csA proteins

-acts like greenbeard allele:

-produces beard (csA protein)

-recognizes other cells with beards (adhesion)

-can it discriminate?

*On agar plates in the lab, wildtype cells are suckers...

In soil, wild-type cells are greenbeard altruists.

If greenbeards are in the stalk, how can the allele suvive?