chp 9: kinship/ relatedness Flashcards
who tested genetic relatedness through alarm calls in Belding’s ground squirrels
paul sherman
what did paul sherman find
genetic relatedness plays an important role in how natural selection favors squirrels emitting alarm calls when a predator is detected
who gave more calls
adult females then 1-year females then juvenile females
why do females give alarm calls so often
due to gender differences in migration and proximity to genetic kin
in belding’s ground squirrels how do males mate
emigrate from their group to find mates
in belding’s ground squirrels how do females mate
they live their entire lives in their natal area (place of birth)
who is closer to their genetic relatives in belding’s ground squirrels
females
when females do move away from natal groups does their alarm calls increase or decrease
decrease
what is kinship
relationship through common characteristics or a common origin (connection)
what is a common leading factor to social behavior
cooperation among relatives
who offered evolutionary explanations about inclusive fitness theory through kin selection
maynard smith and hamilton
kin selection
1) is the process by which traits are favored because of their beneficial effects on the survival of relatives
2) type of natural selection in which an individual attempts to ensure the survival of its own genes by protecting closely related individuals
why is a trait being favored?
because kin share genes and these genes produce behaviors that increase the reproductive success of relatives those genes will in turn be represented increasingly
natural selection favors what kind of gene
a gene that is responsible for behavior that maximizes an individual’s survival and reproduction (regardless of its effect on other individuals)
what does kin selection theory predict
all other things equal, individuals will be more likely to favor kin than non kin, and close kin more than distant kin
what accounts for most altruistic social behavior
relatedness and inclusive fitness
altruism or selflessness
when an animal behaves in a way that reduces their individual fitness but increases the fitness of others
altruism can be explained by
inclusive fitness
inclusive fitness
the total effect an individual has on proliferating its genes by producing offspring and helping close relatives produce offspring
examples of animals with altruistic behaviors
belding’s ground squirrels = alarm call
african bee-eaters, scrub jays = cooperative breeding
bees and other hymenopterous insects
mole rats of asia
random house define kinship as
“family relationship” or relatedness
evolutionary definition of kinship
probability that individuals share genes that they have inherited from common ancestors
genes shared through common ancestor is referred to as
“indentical by descent”
relatedness is labeled
r
relatedness
the probability that two individuals share genes that are identical by descent
in sexually reproductive organisms, sibling relatedness value is
0.5
r in parent to child or siblings
0.5
r in grandparent to grandchild
0.25
r in uncle to nieces or nephew to cousins
0.125
what type of measure did hamilton propose for predicting when natural selection would favor altruistic acts amoung related individuals
quantitative (aE1rb)-c>0
b
the benefit that other receive from the trait/gene (safety when call is made)
c
the cost accrued to the individual expressing the trait (danger of being killed)
r
probability of relatedness (closeness among the group)
a
how many individuals affected by the trait
3 key variables in an altruistic act
1) benefit to the recipient (favors)
2) cost to the altruist
3) coefficient of relatedness
coefficient of relatedness
the probability that if two individuals hare a parent or ancestor, a gene in one individual will also be present in the second
when relatedness (r) is high, then
rb is > than c
as A increases, the natural selection for the trait is
more favored
when does natural selection favor altruism
when the benefit to the recipient multiplied by the coefficient of relatedness exceeds the cost to the altruist rb>C
the inequality is called
hamilton’s rule
disadvantage of hamilton’s rule
benefit (b) and cost (c) are difficult to measure in nature
who reformulated hamilton’s rule
jerram brown
brown’s “offspring rule” solved both problems by using what as the currency to measure
offspring
offspring rule
provides a means to estimate fitness benefits and costs of assisting kin
helping kin increases or decreases the number of fledglings
increases
reciprocal altruism
altruistic behavior toward unrelated individuals which can be adaptive if the aided individual returns the favor in the future
who developed an evolutionary theory to of the family
steve emlen
steve emlen’s theory tests
specific predictions regarding the formation, stability, and social dynamics of biology
what are the building blocks for steve emlen’s theory
1) kin selection
2) ecological constraints theory
3) reproductive skew theory
ecological constraints theory
examines distribution of mature offspring
reproductive skew theory
examines how reproduction is divided among potential breeders by predicting conditions that should favor conflict or cooperation over breeding decisions
family dynamics prediction 1
family dynamics will be unstable, disintegrating when acceptable reproductive opportunities materialize elsewhere
example of prediction 1
super fairy wren = male siblings help raise young but leave nest when time to mate
humans = leave home when time to mate or marry
family dynamics prediction 2
family stability will be greatest in those groups controlling high-quality resources
example of prediction 2
humans = kids will leave home when there is diminishing resources (space) but stay when the resources are abundant (food). Trump, bush, and kennedy can bass down those dynasties and they are very tight knit
family dynamics prediction 4
assistance in rearing offspring (cooperative breeding) will be expressed to the greastest extent between those family members that are closest genetic relatives
under hamilton’s rule, when genetic relatedness is high coefficient of relatedness value
increases interaction between individuals and the more likely they are to help one another which affects distribution of assistance
in haplodiploid genetic systems who is haploid and who is diploid
males = haploid
females = diploid
in haplodiploid genetic systems
- sisters are more related by coefficient relatedness of .75 more than their own offspring
- sisters inherit exactly the same gens from their father (100%)
- females go to sundial length to defend a hive full of their sisters or kill their own offspring
which insects have the best policing
vespula germanica and vespula vulgaris
family dynamic prediction 9
replacement mates (step-parent) will invest less in existing offspring than biological parents
infanticide
step parent may attempt to harm/kill their mate’s current offspring since they are not related by blood and they drain resources with no kin based benefits
example of infanticide
avian = step parents destroy clutches containing potential stepchildren
humans = step children suffer child abuse at a higher rate and leave home significantly earlier than children from biologically intact family
family dynamic prediction 13
reproduction with a family will become increasingly shared as the unevenness in social dominance between potential co-breeders decreases
what is used to make prediction 13
optimal skew
optimal skew model
a family of models that predicts the distribution of breeding within a group, as well as the degree of cooperation or conflict over reproductive activities
when does prediction 13 usually take place
in a situation where a male has to fight for the opportunity to mate a female
fighting is more dangerous between
equally matched individuals
- stronger male will compromise with peace gift or sharing mating opportunity
example of this cooperative breeding
humans = marriage in tibet where females marry pairs of brothers
social behavior evolved from
sharing the same gene and trying to keep that gene preserved
parent-offspring conflict (zone of disagreement)
a zone of conflict between how much a given offspring wants in terms of parental resources and how much a parent is willing to give
why do females provide more aid
because they carry the fetus they know that the offspring is their own
parental aid to current offspring should not
kill or severely hamper future reproductive possibilities of the parents
example of parent-offspring conflict
1) weaning = mothers reduce aid while each current brood thinks they deserve the aid more than the others
2) sex ratio = female workers control sex ratio by 3:1 since sisters are 3 times more closely related to the workers than brothers
3) in-utero conflicts = evolutionary conflict starts from selection genes during pregnancy (genes selected in fetus and mother have different interest). fetus genes want to pull nutrients while maternal genes want to limit transfer of excess nutrients
4) infanticide
what happens if the queen dies and is replaced by one of her daughters
workers are equally related to the new queen’s sons and daughters and so they should favor a 1:1 sex ratio
residual reproduction
when a female has more reproductive opportunities in her future
factors in infanticide
age of the female and resource
sibling rivalry
selected genes in individual look for the individual survival interest
what causes sibling rivalry
scarce resources and harsh environment
how can we tell if we are related
by using “internal template” that can be matched to others to gauge relatedness
rule of thumb models
where kin groups are segregated from one another for a long period of time a second form of kin recognition is involved (if it lives in your nest/cave, treat it like kin)
