BIOC54 Post Midterm Notes.docx

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Biological Sciences
Kamini Persaud

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. In many species, there are factors that allow a mother and young recognize each other so that a mother doesn’t end up caring for young that are not hers. Adoption of Genetic strangers: sometimes parents do care for young that are not their own. It’s bad if a parent mistakenly kills their own offspring so (for example gulls) simply feed any chicks that confidently approach them for food. But this allows strangers to succeed too. Adoption doesn’t significantly cost the parent.AND HENCE evolve In bluebirds, if a male joins a female which she is fertile, he will care for the offspring. If he joins her when the fertile period is over, then the rule is “no parental care at all.” Hence this is a strict dichotomy in some species. Parasitism: some species lay their eggs in the nests of others (eg. Cucko
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