Exam Two Prep Flashcards
(148 cards)
1
Q
how to measure heritable variation
A
phenotype = genotypic effects + enviornmental effects
Vp = Vg + Eg
2
Q
how is genetic variance broken down
A
Va= additive genetic variance
Vd= dominance variance
Vi= epistatic variance
3
Q
additive genetic variance
Va
A
variation due to additive effects of alleles at aall relevant loci
- inherritance of alleles
4
Q
dominance variance
Vd
A
variation associated with interactions between alleles at a specific locus
affects the phenotype derived from genes, not affected by how genes are inherited
5
Q
epistatic variance
Vi
A
genetic variation associated with non-additive interactions between different alleles in different loci
6
Q
heritabillity
h^2
A
proportion of the variance in phenotype that is transmissible from parents to offspring
influenced by natural selection
heritabillity ranges from 0 to 1,
heritabillity= 1 trait influenced by genetics only
heritabillity = 0 trait influenced by environment
7
Q
what are the measures of heritabillity?
A
broad sense heritabillity (H)
narrow sense heritabillity (h^2)
8
Q
broad sense heritabillity (H)
A
measures the proportion of phenotypic variation due to genetic effects
easy to measure less informative
H= genetic variance/phenotypic variance
9
Q
narrow sense heritabillity (h^2)
A
determines the degree to which offspring resemble their parents
harder to measure more informative
h^2= additive genetic variance/phenotypic variance
10
Q
on a linear graph what is the heritabillity?
A
the slope is the heritabillity
11
Q
Breeder’s equation
A
R=(h^2)(S)
can be used to predict the response to direction selection on a trait
R= response to selection
S= Selection differential
h^2= heritabillity
12
Q
artificial selection
A
“managed evolution” practice of selecting a group of organisms from a population to become the parents of the next
13
Q
truncation point
A
cut off level of phenotype that determines which individuals will be used for breeding purposes
14
Q
Selection differential (S)
A
the difference between mean length of the breeders and mean length of the inital population
strength of selection
15
Q
Response to selection (R)
A
difference between mean length before and after selection
16
Q
breeder’s equation rearranged for heritabillity
A
h^2=R/S
or
h^2= (next gen - original)/(selected- original)
17
Q
modes of selection
A
effects of natural selction on the distribution of a trait
18
Q
what are the three modes of selection
A
directional
stabilizing
disruptive
19
Q
directional selection
A
fitness consitently increases (or decr.) with the value of a trait
mean value of trait will increase or decrease
20
Q
stabilizing selection
A
selection favors intermediate trait
variation of the continuous trait is** reduced**
doesn’t change mean value of trait
21
Q
disruptive selection
A
selection favors extreme phenotypes
variation of trait increases
doesn’t change mean value of a trait
may lead to speciation
22
Q
species
A
smallest evolutionarily independent unit, basic unit of classification
what consititutes a species is highly debated
23
Q
biological species concept
A
a species is a group of interbreeding natural populations that are reproductively isolated from other groups
reproductive isolation is a mechanism of preventing two species from producing viable, fertile offspring
24
Q
types of reproductive barriers
A
prezygotic and postzygotic
25
prezygotic reproductive barriers
prevent mating or fertilization from happening
## Footnote
examples: habitat isolation, behavioral isolation, temporal isolation, mechanical isolation, gametic isolation
26
# example of
habitat isolation
parasites living on different hosts
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# example of
temporal isolation
plants that flower at different times, insects that emerge at different times of year
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# example of
behavioral isolation
different mating calls or dances
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# example of
mechanical isolation
structural differences that prevent mating
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# example of
gametic isolation
sperm of one species cannot fertilize eggs of another
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postzygotic reproductive barriers
prevent a hybird zygote from developing into a viable, fertile adult
| prevent the formation of fertile offspring even if mating does occur
## Footnote
reduces hybrid viabillity and fertillity
32
problems of biological species concept
1. not applicable to asexual organisms
2. difficult to apply in "real world"
3. not applicable to extinct organisms
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morphological species concept
species are sets of organims that ** look similar ** to each other and distinct from others
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problems with morphological species concept
1. descriptions of morphological characteristics are subjective
2. some morphological characters may not reflect evolutionary theory
3. not applicable to organims that are morpholocially indistinguishable but are clearly different lineages
## Footnote
as per 2. an example would be traits produced by convergent evolution
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phylogenetic species concept
species are the smallest monophyletic group on evolutionary tree
36
problems with phylogenetic species concept
1. phylogenies are often unknown
2. cut off for a species is often arbitrary
## Footnote
as per 2. how much genetic distinctiveness is required to seperate one species from another
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general lineage concept
species are evolving metapopulation lineages
| species criterions dont typically arise at the same time or order
## Footnote
attempts to unify all other species concepts
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# under the general lineage concept
species criterions (SC)
evidence for lineage diversification
## Footnote
ex- reproductive incompatible
gentic differention
morphologically distinct
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lineage
lineal descedent from an ancestor
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allopatric speciation
speciation involving geographical separation of populations
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geographical isolation
physical barrier prevents genetic exchange
| basically allopatric
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types of geographical isolation
1. isolation by dispersal
2. isolation by vicariance
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geographic isolation by dispersal
dispersal (migration) past the barrier
| can cause founder event
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geographic seperation by vicariance
when a new geographical barrier appears and seperates a once continuous population
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ring species
new species can arise through circular overlap without limiting gene flow
## Footnote
think about the salamanders aroudn the mountains
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parapatric speciation
speciation event occurs in continuously distributed population without disninct geographical isolation
a hybrid zone is formed
## Footnote
VERY RARE
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sympatric speciation
new species evolve from common ancestor w/o geographical isolation
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# for sympatric speciation
examples of isolation mechanisms
1. habitat isolation
2. temporal isolation
3. behavioral isolation
4. polyploidy
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polyploidization
whole genome is duplicated and double chromosome #
offspring unable to breed with parental species
| two types: autopolyploids and allopolyploids
## Footnote
CAUSES SYMPATRIC SPECIATION
50
autopolyploids
genome duplication within a species
## Footnote
individuals have extra set of chromosmes from **SAME** parental species
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allopolyploids
genome duplication in a hybrid
## Footnote
individuals have extra set of chromosomes from **DIFFERENT** species
52
# How would hybridization affect speciation?
A. Hybridization may slow or reverse differentiation by
allowing gene flow and recombination.
B. Hybridization may accelerate speciation via promoting
adaptive divergence through gene introgression.
C. Hybridization may cause speciation by
allopolyploidization.
D. All of the above.
D. All of the above
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seperation caused by geographical isolation
1. seperation
2. divergence
3. reproductive isolation
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# in terms of speciation caused by geographical isolation
seperation
genetic isolation of populations, some form of **physical isolation** prevents gene flow
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# in terms of speciation caused by geographical isolation
divergence
differentiation among populations, due to natural selection or genetic drift
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# in terms of speciation caused by geographical isolation
reproductive isolation
if physical barrier is removed, populations cannot interbreed
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phylogeny
evolutionary history of a group of organisms
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phylogenetic ( or evolutionary ) tree
graphical summary of evolutionary hsitory
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what does an evolutionary tree demonstrate?
1. hypotheses about relatedness and common ancestry
2. timing of evolutionary modifications (transitions) that occured
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# of a phylogenetic tree
root
ancestral taxon where all other nodes descend
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# of a phylogenetic tree
tips
descendant taxa
## Footnote
basically the modern day species or descendant
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# of a phylogenetic tree
branches
lineages, linear descend from ancestors
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# of a phylogenetic tree
nodes
evolutionary branch points, shared ancestors
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# of a phylogenetic tree
clade
| also known as monophyletic group
group of organisms that include a common ancestor and all of its descendants
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monophyletic group
| also known as a clade
contains single common ancestor and all of its decendants
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paraphyletic group
contains an ancestors and some, but not all of its descendants
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polyphyletic group
contains some of an ancestor's decendants **not** including the ancestor
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synamorphy
shared derived character
| this is what defines monophyletic groups
## Footnote
traits shared between species because they are homologous and derived from a common ancestor
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homoplasy
traits evolved independently in seperate lineages
## Footnote
analogous traits, could evolve throug convergent evolution
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apomorphy
derived character
## Footnote
types: synamorhpy and automorphy
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autamorphy
unique derived character on a particular taxon
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polytomy
when there is multiple splits, evolutionary relationship cannot be fully resolved
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principle of parsimony
a preferred phylogenetic tree is one that requires the minimum number of character changes
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cost of meiosis
females lose 50% of genetic contribution
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problems in phylogeny reconstruction
1. convergent evolution leads to analogous traits that do not reflect evolutionary history
2. homoplasy- traits that have been gained or lost independently in sperate lineages
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multiregional hypothesis
homo erectus evolved in africa and moved into eurasia about two million years ago. homosapiens independently evolved from these
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out of africa hypothesis
abt 200,000 years ago modern humans originated in africa, less than 100,000 years ago they spread across the globe
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pathenogenesis
offspring developed from unfertilized eggs
| allows females to reproduce asexually
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costs of breaking adpated genetic combinations
reproducing sexually may disrupt beneficial genetic combination and lower the mean fitness of offspring
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costs of sexual reproduction
1. cost of meiosis
2. cost of males
3. costs of breaking adapted genetic combinations
4. costs associated with the mating process
| look at these from the female perspective
81
cost of males
males do not provide resource to the next generation, yet femals typically invest half of resources into production from males
## Footnote
cost of having less number of offspring in sexual reproduction due to the production of males
82
costs associated with the mating process
finding a mate, energy spent on courtship, increased risk of predation
risk of disease transmission and parasite infection
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advantages of sexual reproduction
1. lottery hypothesis
2. muller's rachet hypothesis
3. red queen hypothesis
84
lottery hypothesis
sexual reproduction allows organisms to produce genetically diverse offspring
## Footnote
some might be able to surrvive better by chance
not supported by empirical data
85
Muller's rachet hypothesis
sexual reproduction decreases deletrious mutations through recomination
## Footnote
more data supports this hypthesis
86
red queen hypothesis
coevolving species maintains a dynamic equillibrium, sexual reproduction can increase host resistance to parasites
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sexual dimorphism
distinct difference in size or appearance between the sexes of an organism
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anisogamy
fusion of gametes that are dimorphic
## Footnote
term for different sized gametes
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males vs females on reproduction
males will specialize on finding mates
females will specialize on parental effort not mating effort
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secondary sexual characteristics
characters not needed for surrvival or mating but used for competition for mates or mate attraction
## Footnote
evolved through sexual selection
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sexual selection
different reproductive success due to variation among individuals in sucess at getting mates
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who is sexual selection more intense towards
more intense on the sex that is specialized on finding mates
## Footnote
this is typically males
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sexual selection for males
reproductive success is limted by access to mates
males evovle to compete for mates
intrasexual selection
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sexual selection for females
reproductive success is limtied by capacity to produce or raise offspring
females should be choosy
intersexual selection
95
intrasexual selection
| (male-male competition)
compete for breeding territories or access to females
## Footnote
leads to evolution of incr. strength, body size or weaponry
96
sneaky male strategy
males sneak in to access a femal partner, avoiding more dominant males
97
intersexual selection
| (female choice)
selection on males based on female choice
## Footnote
many of the traits that females are attractive to are actually maladpative for the surrvival of the male
98
for females how does reproductive success increase
by mating with males that provide direct or indirect benefits
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# reproductive success
direct benefits
the expression of a male trait may indivate a male's abillity to provide resources
## Footnote
examples- nupitial gifts, territory, parental care
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indirect benefits
the expression of a male trait may indicate genetic quality of a male
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why female organisms are choosy?
1. may directly benefit when they get resources
2. may get better genes for their offspring ( sexy son hypothesis and good genes hypothesis)
3. may have preexisitng sensory biases (sensory biases hypothesis)
102
runaway selection
a secondary sexual trait expressed in one sex becomes genetically correlated with a preference of the trait in the other sex
103
sexy son hypothesis
## Footnote
this is such a weird name
females with a preference for ornamented males will produce sons ith higher mating success
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runaway selection vs sexy son hypothesis
runaway theory explains the evolutionary process **how** males evolved to have a trait based on female preference
sexy son hypothesis explains **why** females are choosy
105
good genes hypothesis
proposes that females select males that have genetic advantages to incr. offspring quality
## Footnote
the male trait that females prefer is a reliable and honest signal of male genetic quality
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good genes hypothesis vs. sexy son hypothesis
sexy son hypothesis - females indirectly benefit from producing attractive sons
good genes hypothesis- females prefer males that give good genes to both her sons and daughters
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honest signals
| example of it at least bc no definition is given
birds that are sick don't have full colorful plumage,
plumage is an honest signal of male's current health condiition
108
handicap principle
suggests that reliable signals must be costly to the signaler
| handicap = secondary sexual trait that females prefer, no good for males
## Footnote
handicap has to be costly so it cannot be cheaply imitated
If truly high quality males are more likely to survive with the handicap, then
handicap will be a reliable indicator to represent male’s overall genetic quality
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sensory bias hypothesis
females preferences result from biases in female sensory system
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examples of reversal in reproductive investment
seahorses, gold specs jawfish and giant water bug
## Footnote
if male investment is higher, males tend to be choosy and females compete
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sex determination system
a bio system that determines if an individual is a male, female, or hermaphorodite
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what determines whether an individual becomes male or female
1. genotypical sex determination
2. enviormental sex determination
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genotypic sex determination
sex of individual is determined by genotype
| ex: mammals, birds, amphibians, most insects, etc
## Footnote
two types: heterogametic sex and homogametic sex
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heterogametic sex
the sex that has two different sex chromosmes
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homogametic sex
the sex that has one type of sex chromosome
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sex determination in mammals
sex is determined by the presence of a Y chromosome
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sex determination in birds
sex is determined by the Z and W chromosomes
| male = ZZ female ZW
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haplodiploidy
males develop from haploid unfertilized eggs. females develop from diploid fertilized zygotes
## Footnote
this is the sex determination mechanism in bees ants and wasps
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enviornmental sex determination
influenced by enviornmental cues
| cues can be temp, pH, social interactions
## Footnote
ex: many reptiles, some fish
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# true or false
sex is controlled by one master-switch gene
false, in model organisms yes but multiple genes can influence sex( polygenic sex determination)
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hermaphorditism
organism is able to produce both male and female gametes
| happens to many fish
## Footnote
types: protandry and protogyny
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protandry
organism begins life as a male, changes into a female as it incr. in size
## Footnote
occurs when females gain more in reproductive success as they incr. in size
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protogyny
an organism begins life as a female, changes into a male as it incr. in size
## Footnote
occurs when males gain more reproductive sucesss
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social behaviors
interaction among individuals of the same species in ways other than mating
| can be cooperative or conflicting
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actors
individuals that perform social behavior
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recipients
individuals that actor interact with
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four types of social interactions
1. mutual benefit
2. selfishness
3. altruism
4. spite
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mutual benefit
both actor and recipient gain fitness
| ex: cooperative breeding birds, communal nesting
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selfishness
actor acts in a manner that increases its fitness to the demise of another
| ex: cannibalism in cane toad- provides nutrients + reduces competition
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spite
actor harms its own fitness and the fitness of another
| ex: production of bacteria in two e.coli strands
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altruism
acting ot increase another individual fitness at a cosst to ones own
| ex: alarm calling in bedling's ground squirrel (trilling)
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hamilton's rule
| not the equation
individuals engage in altrusitic behavior if the indirect benefits derived from this act are greater than its cost
133
hamilton's rule equation
Br- C>0
## Footnote
B- benefit to recipient
r- coefficient of relatedness
C- cost to the donor
134
coefficient of relationship
probabillity of the homologous alleles in two indivudals are indentical by descent from recent common ancestor
## Footnote
when r is higher, individuals are more closely related
135
# under hamilton's rules
fitness has two components
direct fitness- reproductive success of the individuals and their offspring
indirect fitness - reproductive success of the individuals relatives
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inclusive fitness
direct and indirect fitness of an individual
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kin selection
a process by which a behavioral act is facored due to its beneficial effects on relatives
organisms are more likely to perform altruistic acts toward their relatives
## Footnote
altruistic behavior is a result of kin selection
natural selection that favors indirect fitness of individuals
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reciprocal altruism
altruistic behaviors evolved among unrelated individuals through repeated reciprocal interactions
| **related or unrelated and very rare**
## Footnote
an individual helos another individual with expepectation that it will be retrurned
139
kin recognition
abillity to recognize and identify close relatives
| **closely related**
## Footnote
direct and indirect
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Can kin selection occur without kin recognition?
yes
141
direct kin recognition
based on a specific chemical vocal or other cues
142
indirect kin recognition
like a location of a nest
## Footnote
think about the cuckoo bird video from lecture
143
parent offsrping conflict
conflict may occur when parents an offspring disagree abt. fitness interests
## Footnote
types: weaning conflict and sibicide
144
what conditions can reciprocal altruism evolve
1. benefit to the recipient of act is greater than cost to the actor
2. capable of recognizing each otther
3. repeated interaction between individuals
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weaning conflict
disagreements between parents and offspring abt the amt and duration of parental provisioning
## Footnote
each offspring will demand more investment, where parents want to give equal investment
146
siblicide
extreme sibling rivalry where they will attack and kill each other in different occasions
## Footnote
found in masked and blue footed booby
147
eusociality
extreme form of altruism
nonreproducive individuals participate in the cooperative care of young
| ants, bees etc
## Footnote
overlapping gens. between parents and offspring
cooperative brood care
specialized group of non repoductive individuals
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