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BIOC54H3 (13)
Lecture

Lecture # 7

5 Pages
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Department
Biological Sciences
Course Code
BIOC54H3
Professor
Maydianne Andrade

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Lecture 7
Polyandry: where one female males with many males. In this system males are
generally socially monogamous
Polyandry: occurs when female LRS is strongly limited by the # of clutches she can
successfully rear in a season.
And this limitation is for extrinsic reasons : not just about how much food she can
acquire to get large number of eggs, but instead, after the females produce the eggs, she
is at a risk of unpredicatable loss of all those offsprings.
oThis happens due to unpredicted clutch failure
This occurs due to high predation rates
High rates of sperm inviability
Highly variable food availability
If there is high rates of clutch failure, females can increase the # of eggs in one clutch
oUnder these circumstances there is high rates of clutch failure
Another method is to increase the # of clutches
oProblem: females can only care for one clutch, so this doesnt work
oSo the females much seek multiple partners to care for all those clutches
After producing eggs, females abandon the broods leaving the males to care for them
and the males will take care of the broods (this is polyandry). This way the female is free
to capitalize on EPP
There are different types of polyandry depending on the differential ecology and biology
of the males
Male defence: Phlalaropes : they show sex role reversals.
oFemales are the brightly coloured sex
oThey fight over males, and they produce 4 clutches, each protected by a different
male
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oThere is also very variable food availability
oThere is also very frequent egg mortality due to predation
Jacanas: semi-aquatic birds : females defend breeding territories.
oThere are several males per territory, and the males exclusively care for the eggs
oAnd there is again very high egg mortality due to predation
oFemales actually infanticidal and clutches can fail for that reason as well
Females emancipation from care is essential in making the females mating system
polyandrous in this care
Parental Care
Parental care : why individuals provide care to the offspring
There is a variation in parental care in animals
oAfrican elephants nurse their young for 6 years
oPenguins : male care for eggs while females go to feed, and both males and
females feed the young after.
oAphids : they give birth to live youngs, that as soon as they are born are able to
walk off and care for themselves.
oSea turtles : females bury their eggs in the sand
Then they leave the eggs alone and the sea turtles have to find their way
home
Tree-hoppers
oThey guard their eggs /offsprings
oIf a wasp approaches a branch , the female kicks them
Parental investment can be studied using cost –benefit analysis
oBenefits : increased survival and success of the offspring
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Description
Lecture 7 Polyandry: where one female males with many males. In this system males are generally socially monogamous Polyandry: occurs when female LRS is strongly limited by the # of clutches she can successfully rear in a season. And this limitation is for extrinsic reasons : not just about how much food she can acquire to get large number of eggs, but instead, after the females produce the eggs, she is at a risk of unpredicatable loss of all those offsprings. o This happens due to unpredicted clutch failure This occurs due to high predation rates High rates of sperm inviability Highly variable food availability If there is high rates of clutch failure, females can increase the # of eggs in one clutch o Under these circumstances there is high rates of clutch failure Another method is to increase the # of clutches o Problem: females can only care for one clutch, so this doesnt work o So the females much seek multiple partners to care for all those clutches After producing eggs, females abandon the broods leaving the males to care for them and the males will take care of the broods (this is polyandry). This way the female is free to capitalize on EPP There are different types of polyandry depending on the differential ecology and biology of the males Male defence: Phlalaropes : they show sex role reversals. o Females are the brightly coloured sex o They fight over males, and they produce 4 clutches, each protected by a different male www.notesolution.com
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