BIOLOGY 1M03 Lecture Notes - Lecture 5: Shared Parenting, Homo Sapiens, Alarm Clock
29 Jun 2018
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How can evolution explain helping others?
Kin selection (inclusive fitness). The fact that if the genes for helping are likely to be
shared in common with the individual being helped then natural selection will sort
that out. Important to recognize that when you think about Hamilton’s rule, animals
themselves don’t have to figure that out, the animals that tend to behave in that
way, that have a genetic pre-disposition to behave towards the relative in a way that
promotes relative genes at a sufficiently low cost to the individuals, those individuals
will be favored by natural selection. What about non-kin (friends)?
Reciprocal Altruism
Effectively cooperation with a time lag, the two parties involved are benefitting, there
is a time lag involved. Not anything natural selection will eliminate because both
parties end up doing better
If the fitness benefit to the recipient > the fitness cost to the donor, both participants
will gain if help is reciprocated at a later date
If I am short on change, my buddy will buy me coffee and I’ll buy him a coffee in the
future. Not all favors translate, when we are in a position to help a friend, we help
them. But when they are in a position of helping us they will us.
Cooperation with a time delay
oBenefit-R > Cost-D
oLong-term association (opportunity for reciprocation)
oIndividual recognition. You have to be able to recognize who helped you.
oDetection and punishment of Cheaters. Some sort of cost to cheating if you get
caught.
Vampire Bats
Feed on blood and Cannot survive > 3 days without feeding
1) Associate with kin and non-kin roast mates. They roast in holes and trees or under
trees. They have a group that they roast with, they return to the same group.
2) Regurgitate to kin. If they have a relative that is in need, they will give them blood
and will save them from potentially starving to death.
3) Also regurgitate to non-kin that regurgitate to them. They develop alliances with
non-kin and exchange blood meals when in need
Vampire Bat Blood regurgitation
So how does that work? This graph looks at the percentage of pre-fed weight
plotted against hours to death from starvation. The donor is up there, the donor has
just fed for the night he was successful, and she was successful at feeding and she
now is 100% of pre-fed weight. Now has some
where over 50 hours that she can survive before
she will starve, the recipient his weight is 88%, he is
getting down there and right now he has about 30
hours until he is likely to die. Now if we look at the
cost and benefits, the certain volume of blood she
will feed to him, if she feeds 5% of her blood from
stored, she will drop down to second point, within 52
hours of mortality, she started at 55 or so. A low
find more resources at oneclass.com
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cost, but the benefit because of the shape of curve, the benefit, if he now is gaining
the weight we are talking about, he goes up in weight, to the point where he will
benefit a huge amount, this will bring him to the second point, at first he was within 5
hours of dying, this small contribution which doesn’t cost her much, brings him back
to 30 hours. This curve: benefit hours to death from starvation, you can see that a
small contribution can benefit hugely by bringing it back to this point.
Cooperation with a time delay
oBenefitR> CostD
oLong term association (opportunity for reciprocation)
oIndividual recognition within these animals.
oPossible detection and punishment of cheaters
Possible example of reciprocal altruism
Smooth-billed anis in Puerto Rico 2011 - Looking at referential alarm calling. Means
I will give a call, nature of call should be a referent to individuals listening that will
cause them to change their behavior in a functional way. It is different from a
different referential call that would be for a different predator. Identifying what type
of predator the individual has to be worried about
“Referential alarm calling”
oOne call for terrestrial predators
oSeparate call for aerial predators
In Peurto Rico – a number of predators that will cause problems for anis. Examples
include Peregrine Falcon and The red tailed hawk.
Red-tailed Hawk
Terrestrial
Alarm (left)
Aerial Alarm
(chlurp) (right)
Sonograph that
shows the 2
call types.
Take sonogram
and take them apart and take a various features
On duration and entropy (chaotic vocalization) is different
Combine various vocal traits in to a cluster analysis –
combines features of similarity and allows you to plot 3
different call types on this discriminate function plot. Ahnee
alarm on top, generally distinct from the chlurp which are
on right and distinct from ahnee call
White Noise Control (matched to specific chlurp played to
group)
In this study we used playback to eliminate possibility that these calls were simply
random, that the animal that heard them would respond in an appropriate way by
either watching the individual that called and see what he does or by looking up and
see who’s there.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The fact that if the genes for helping are likely to be shared in common with the individual being helped then natural selection will sort that out. Effectively cooperation with a time lag, the two parties involved are benefitting, there is a time lag involved. Not anything natural selection will eliminate because both parties end up doing better. If the fitness benefit to the recipient > the fitness cost to the donor, both participants will gain if help is reciprocated at a later date. If i am short on change, my buddy will buy me coffee and i"ll buy him a coffee in the future. Not all favors translate, when we are in a position to help a friend, we help them. But when they are in a position of helping us they will us. Cooperation with a time delay: benefit-r > cost-d, long-term association (opportunity for reciprocation, individual recognition.
