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Parental Care

Parental Care. So far …. Rules of the particular mating system have been exercised. Mates have been secured. Offspring to care for. What are the behavioural and evolutionary rules for raising offspring?. Relationship between mating systems and parenting.

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Parental Care

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  1. Parental Care

  2. So far … Rules of the particular mating system have been exercised Mates have been secured Offspring to care for What are the behavioural and evolutionary rules for raising offspring?

  3. Relationship between mating systems and parenting 1. Monogamy - both male and female participate in rearing e.g. trumpeter swan

  4. Relationship between mating systems and parenting 2. Polygyny - one male, several females - usually the female provides care

  5. Relationship between mating systems and parenting 3. Polyandry - one female, several males - usually the male provides care -Wilson’s phalarope

  6. Relationship between mating systems and parenting 3. Polygynandry - promiscuous - either sex could provide parental care

  7. Relationship between mating systems and parenting Phylogenetically Gross and Sargeant ‘85 - Survey of Teleost fish Teleosts 79% - no parental care 21% parental care Two parents >75% One parent <25% Internal fertilizer External fertilizer 86% female 14% male 30% female 70% male

  8. What governs which sex should invest? 1. Anisogamy - female has already made greater investment 2. Confidence in parentage -species with internal fertilization -male should be inclined to desert -female should be inclined to care 3. Association with embryo - sex most closely associated with embryo should offer care

  9. Parental investment Any investment in an offspring that increases its chances of survival and reproduction at the expense of the parents’ ability to invest in other offspring

  10. Parental investment Temporal component MALE FEMALE Cumulative investment Territory Mating /egg laying Incubation Feeding Fledging

  11. Parental investment Temptation to desert MALE FEMALE Cumulative investment Territory Mating /egg laying Incubation Feeding Fledging

  12. Parental investment Any investment in an offspring that increases its chances of survival and reproduction at the expense of the parents’ ability to invest in other offspring

  13. Parental investment Rhesus monkeys % time in contact % time rejected 10 20 30 Weeks

  14. Parental investment Budgies Log feeding rate Offspring weight

  15. Parental investment Budgies With male Female alone Begging Rate

  16. Parent offspring conflict At some point, the parent-offspring relationship is terminated Why and who determines this?

  17. Parent offspring conflict Trivers - looked at benefit/cost ratio to parent Benefit: Gain in survivorship from investing in offspring Cost: Inability to invest in other offspring

  18. Parent offspring conflict Trivers 5 4 3 2 1 0.5 0.25 P O Time of conflict B/C ratio O P Time

  19. Maximum benefit for offspring Parent offspring conflict Conflict during infancy Maximum reproductive success for parent Benefit or Cost 1/2 Cost Level of Parental Investment

  20. Sibling rivalry Corollary of parent/offspring investment -any offspring more interested in its own survival more than in its siblings’ survival - if any siblings benefit:cost ratio is <0.5 - conflict rsiblings = 0.5

  21. Sibling rivalry Mock and Parker (1997) -HIERARCHY MODEL Total amount of food brought by parents

  22. Sibling rivalry Does this model explain observations on sibling rivalry? Cattle egrets

  23. Sibling rivalry Does this model explain observations on sibling rivalry? Cattle egrets % share Early Mid Late

  24. Sibling rivalry Great Blue Heron Weight at day 14 1,2 3 Lost sib 4 No loss 5 Chick number

  25. Parent Offspring Conflict in Utero Haig (‘93) -mother - selected to limit nutrient transfer - fetus - selected to increase nutrient transfer

  26. Parent Offspring Conflict in Utero Haig (‘93) Fetal cells migrate to endometrium Fetal cells make constriction of arteries more difficult Benefits to fetus a. hormone release into female’s blood b. nutrients under fetal control

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