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Lecture 9

BIO318 Lecture 9 (Oct 7).docx

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Sanja Hinic- Frlog

BIO318 Lecture 9 - Explaining sex differences (and species differences) in when organisms die of “old age” (senescence) o Males have massive burst of breeding and in which they really go for it and they get preyed upon a lot o Sex differences in aging; males die of old age around 1 year while females can live for a few years - Evolution of senescence o Fitness 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 o How 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) o What 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 o Comparing 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 o Predictions about species and sex differences - Male battles and the evolution of sneaky sex: o Assessing the social environment & phenotypic plasticity o Selective maintenance of alternative phenotypes o What is sexual selection?  Selection of context of sexual competition o Inter: between the sexes (males and females) o Intra: males competing directly with each other - Looking at two ways of males obtaining mates but may equal to same fitness - 22% of all described species are beetles - Male battles and the evolution of sneaky sex o Dung beetles o Rolling dung balls and used for the larvae by laying egg on it - Onthophagus acuminatus o Don’t form a ball but they just form the burrows underneath the dung o The dung rains down into the burrows but it really depends on the amount o Dung quality also varies depending on the season; when fruits are available to the monkeys, the dung are of high quality because of the protein and when it’s only leaves available, the dung made by monkeys are of lower quality o If the male is larger than most of its rivals, it will guard the females; if the male is smaller than most rivals, it will sneak matings with females being protected and avoid fighting altogeth
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