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Lecture 9

BIO318Y5 Lecture Notes - Lecture 9: Dung Beetle, Antagonistic Pleiotropy Hypothesis, Onthophagus

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Sanja Hinic- Frlog

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BIO318 Lecture 9
- Explaining sex differences (and species differences) in when organisms die of “old age”
oMales have massive burst of breeding and in which they really go for it and they
get preyed upon a lot
oSex differences in aging; males die of old age around 1 year while females can
live for a few years
- Evolution of senescence
oFitness of lethal mutation acting at age 20 vs. one acting at age 80
Basically no fitness if you die at age 20 because at 20, people barely
reproduce yet
The gene will be passed on at a higher rate if you’re
oHow is selection affected by high risk of predation 20-80?
This shows you why some animals live longer than other before they died
of senescence (natural causes)
oWhat happens if this age-80 mutation enhances reproduction age 20-30
(antagonistic pleiotropy)
Pleiotropy means more than one effect on genotype?
Some benefit during reproduction age
oComparing rats and bats
Rats are constantly being preyed upon so there are lots of external
causes of death
Bats have wings so that it’s harder for predators to catch them
If you bring bats and mouse into the lab, the mouse would still die earlier
due to senescence and bats can still for many, many years
oPredictions about species and sex differences
- Male battles and the evolution of sneaky sex:
oAssessing the social environment & phenotypic plasticity
oSelective maintenance of alternative phenotypes
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