Week 9 BIOC54.docx

10 Pages
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Department
Biological Sciences
Course Code
BIOC54H3
Professor
Kamini Persaud

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Week 9 Parental Care CH 12 p421453 CH 13 470492 The Evolution of Parental Care The CostBenefit Analysis of Parental CareBirds should adjust their provisioning behaviour adaptively in accordance with 2 key factors 1 the nature of the predator 2 the annual mortality rate for breeding adultsIn Low Adult mortalityparents should spend more time avoiding predators since they will have a better chance at rearing more offspringIn High Mortalityparents should invest more time in raising offspring since they may not live long enough to rear moreExp NA robin shortlived and SA rufousbellied thrush longlivedPlayed chirpingsongsound of predator and documented their behaviourWhen a nest predator was around the bird spent less time going to their nest to avoid the predator finding it but the robins visited areas near the nest more frequentlyWhen an adult predator was around both species again spent less time around their nest but the thrushes also delayed themselves when travelling back to the nestWhy More care by Mothers than Fathers Although both parents may be present to raise offspring more mothers become maternal rather than fathers becoming paternalMaternal care evolves more readily than paternal care tree hoppers phylogeny observation Explanation 1 Since females have already invested time and energy in making eggs they have a special incentive to make sure that their large initial gametic investment is not wastednot seen in all species European Earwigs femalesoften stay with a clutch of eggs laid in a burrow waiting for them to hatch in order to feed larvae offspringThis ensures the larvae survive which is beneficial for the motherA cost however is that the laying a clutch of eggs and tending to them is a weeks more time than those mothers that do not provide the extra care Explanation 2if the cost of parental investment is lower in females than in males than it might tip the scale for more females investing the time and energyEx If males were to invest in parental care in species where females have more than 1 mate the offspring that are his descendants would only be 80 45 whereas for the female it would be a sure 100Therefore it is a more favourable benefittocost ration for females to rear young than malesExceptions to the RuleMaleonly parental care is actually common among fishesNo apparent tradeoff when mate attraction females revolves around male care of eggsEx Stickleback females Also the more eggs in a males nest the safer they are likely to be due to the dilution effectIn this case females would be at a loss if
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