BIOC54H3 Study Guide - Midterm Guide: Cowbird, Superb Fairywren, Paternal Care

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9 May 2012
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4/18/2012 9:16:00 AM
Parental Care
Cost-benefit analysis of parental care: Parental care needed to enhance survival of
offspring but dangers to the parents also exist (eg. Predators). Ghalambor and
Martin predicted that parent birds should adapt their parental care depending on
two factors: (1) nature of the predator- does it eat the prey or the adults? (2)
annual mortality rate of adults. If mortality is low, chances to reproduce again in
other seasons is high so adult birds should try to secure their own survival. If adult
mortality is high, adult birds should make sure their offspring survive since their
own chances of survival are limited and hence they may not be able to have
another clutch.
Why is maternal care more common? Perhaps,
o because females have already invested so much in an egg, they are more
inclined to make sure their offspring live.
But this theory fails with some species that lay expensive-to-make eggs
and then abandon them.
Perhaps: it is more costly for males to care for the young since all of the
young may not be his. But all of a female’s young are hers, so less costly
for her.
Male Water Bugs: eggs laid on the back of the male. He pumps up and down in the
water to keep aerated water around the eggs. Paternal care essential for egg
development in this species. Eggs are large and need a lot of oxygen. Large eggs
needed because they allow the first instar to be larger, and hence the adult insect
to be larger than other species. Why not females but males (as parent) though?
Similar to fish. Males who are brooding a clutch of eggs attract a second female.
Also, females are able to spend more time eating to increase their own size and lay
more eggs since they are not tied down to brooding.
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