1. 18. Paternal Care

2. Parental Care Includes all behavior directed towards offspring Feeding
Protecting
Predators
Elements
Teaching

3. Parental care Very costly behavior Time Energy Vulnerable to predation
emperor penguin
red shouldered hawk
earwig
tarantula hawk

4. Evolution of parental care
Bigger gametes
Increase zygote size
Increased survival
More gametes
Increase potential number of offspring
Females initial investment more than males
(larger gamete size, internal development in some animals)

5. Parental Investment Lots of zygotes Clutch of Offspring
Little care provided
Clutch of Offspring
Some care provided
Greater (longer) parental investment
Robert Trivers

6. Parental Investment
The fewer the offspring the greater the post-natal care provided; per offspring

7. Parental Investment
The fewer the offspring the greater the post-natal care provided; per offspring

8. Parental Investment
However, the smaller the embryo the greater the number that can be produced.

9. Evolution of parental care
Females have a greater incentive to make sure their gametic investment is not wasted.
There females often provide the majority of parental care.

10. Evolution of parental care
Investment on current offspring
Increased investment = increased probability of young surviving
AND increased fitness for parents
Trade off between current and future reproduction
Time, energy, risks spent by parent on current offspring (parental investment)
influence possibility of having future offspring

11. Evolution of parental care
Potential tradeoff:
More energy invested now, less energy available for future reproductive efforts.
Increased parental investment can affect survival of adults.
Potentially decreasing fitness
Parental care investment is subject to selection.
Graph 1) feamles time to spawn again
Graph 2) males time to spawn again
Females provide more care, so males are able to reproduce faster

12. Life History Life history traits
characteristics of an individual that influence survival and reproduction
Age at maturity
House Mouse
African elephant
Atlantic Salmon
2 months
years
3-6 years

13. Life History Life history traits
characteristics of an individual that influence survival and reproduction
Number of offspring
House Mouse
African elephant
Atlantic Salmon
5-8 young every month
1 calf every 3-8 years
1,500 to 8,000 eggs once

14. Number of reproductive events
Life History
Life history traits
characteristics of an individual that influence survival and reproduction
Number of reproductive events
House Mouse
African elephant
Atlantic Salmon
~6-12
~3-10 1
(interoparous > 1)
(semelparous = 1)

15. Life History Life history traits
characteristics of an individual that influence survival and reproduction
Lifespan
House Mouse
African elephant
Atlantic Salmon
2 Years
60-70 Years
3-6 Years

16. Remember EPCs…
Parental care should be proportional to probability offspring are yours.
Females can be quite confident of maternity
Males (when females mate multiply) are less confident of paternity.

17. Opportunity for Polygyny
Variance in reproductive success usually greater for males than females
For example in polygynous, lekking species
Times spent caring for offspring = less time getting more mates.

18. Opportunity for Polygyny
The potential reproductive rate is greater for males than females
Cost / benefit ratio for parenting different between sexes
Cost of parental care is greater for males.

19. Predicting Male care In male bias systems care is more common
Females limited by number of eggs, gestation
so males increase success by providing care
Female bias more opportunities to reproduce
Males likelihood to desert increases

20. Australian mallee fowl
Bi-parental care
Bi-parental care is common (particularly in birds).
In many species, males provide more care than females.
Australian mallee fowl
Greater rhea
Seahorses
African cichlids

21. Male uniparental care Females lay eggs, then provide no care
Males provide care
Mouth Brooding
Nest Guarding

22. Male uniparental care
A female (left) and male (right) Solenosteira macrospira .
The male's shell is covered with numerous egg cases
After mating, females deposit egg cases on their mate's shell
The males carry this burden (which can exceed 50% of the male's wet mass) until eggs hatch

23. Male uniparental care Giant water bugs (Belostomatidae)
Large bugs, eggs also larger than typical aquatic insect.
Need to exchange gases (CO2 out, O2 in)
which is easier out of water.

24. Males moisten eggs laid out of water
Males carry eggs glued to back
No parental care
Giant water bugs

25. Caring for the right offspring
Offspring recognition in colonial species
Discriminating parental care
Mexican free tailed bat

26. Caring for the right offspring
Offspring recognition in colonial species
Cliff swallows can recognize own young, rough winged swallows cannot
cliff swallows
colonial
barn swallows
solitary

27. Caring for the right offspring
Offspring recognition in colonial species

28. Caring for the wrong offspring
It is not worth making a mistake and not caring for your own offspring!
recognition systems are not perfect
Communal care of offspring common in some species that live in groups.
Dwarf mongoose

29. Optimal Threshold Model
signals you want to accept
signals you want
to reject
rejection errors
acceptance errors
adapted from Reeve 1989, Starks 2003

30. Adoption Intra- and Interspecific
Parents will often care for offspring that are not their own
Not resource limited
Decrease risk to own offspring

31. Adoption Adoption increases survival
If the abandoned offspring can find a foster parent

32. Caring for the wrong offspring
Brood parasites - cowbirds, cuckoos

33. Caring for the wrong offspring
Brood parasites - cowbirds, cuckoos

34. shiny cowbird bronzed cowbird screaming cowbird brown-headed cowbird
TOP: # of host species parasitized by that particalar cowbird
BOTTOM: Genetic relationship of parasitic cowbirds

35. 3 species of cowbirds in northern Argentina
bay-winged cowbird
screaming cowbird
shiny cowbird
colonial, builds own nests. Egg dumping?
lays eggs in nests of 1 species - the bay winged cowbird
lays eggs in nests of 176 different species

36. Brood parasitism
Parasitism success dependent on being able to convince host eggs are their own

37. Brood parasitism
Parasites can also remove hosts eggs to increase care given to their own
And ultimately survival/success.

38. Brood parasitism
Parasite can also remove competition

39. Key to brood parasite success
Size disparity important in success of brood parasites
Since parasite parents do not always know when hosts eggs were laid
Parasite young have to be larger at hatching, and grow faster

40. Nest/Den Construction
Habitat Choice
Territorial
Safety
Dens (or roosts) consist of pre-existing structures
Not labor intensive
Nests are constructed
Energetic and time costs
Burrows & Mounds

41. Sibling Conflict Sibling aggression and siblicide
Occurs when resources are variable or in short supply?
Offspring compete for resources (they only share 50% of genes)

42. Sibling Conflict Scramble Competition Preferential feeding
Every mouth for themselves
Preferential feeding
Largest/Healthiest eat first (Competition)
Hungriest eat first

44. Adaptive parental strategies
masked booby
have two eggs, first hatched chick always kills second chick
blue-footed booby
have two eggs, often raise two young

45. Parent-offspring conflict
Selection may act on parents and offspring differently.
Some actions that increase fitness of offspring may reduce fitness of parents.

46. Begging From offspring perspective: From parent perspective:
Way of attracting food
Reflect actual needs of the young (Honest)
Greed (dishonest)
From parent perspective:
Way of identifying hungry offspring
Ensure offspring are being fed enough

47. Asynchronous Hatching
Birth order can promote or reduce sibling conflict and parental favoritism
Synchronous hatching, all offspring born at same time
Greater food demand
Can reduce parental efficiency/success

48. Offspring size disparity
Typically first young will be largest and most likely to succeed
Fledge
Females can adjust by increasing investment (larger eggs) for later eggs produced
Enough so that later hatchinglings are born larger, and are able to compete for food

49. Parental favoritism
Likely occurs when resources are variable and adults have more young than they can raise (bet hedging)
Females can invest in eggs differently (even choose sex in some species).
Young can be fed preferentially.
Seychelles warbler

50. Can parents control sex of offspring?
Seychelles Warbler

51. Control of offspring sex
Haplo/diploid organisms (like ants, bees and wasps)
Fertilized egg = female ; un-fertilized egg = male
Temperature Dependent Sex Determination (TSD)
many reptiles

52. Nest Help
In some animals, juveniles stay to help second nesting effort.
More often female juveniles.
Both direct and indirect benefits.
Direct (learning about maternal care)
Indirect (inclusive fitness by helping rear related offspring
voles
magpie jays

53. Nest Help Leads to overlapping generations
Key step in the evolution of sociality?

54. Genetics basis for mating systems / parental care.
prairie voles
Monogamous
male parental care
meadow voles
polygymous
no male parental care

55. Genetics basis for mating systems / parental care.
In male prairie voles, vasopressin and dopamine in the forebrain regulate affiliation between mates (bond formation).
Vasopressin receptor is expressed at higher levels in monogamous species than polygynous species.
Lim and colleagues, used a viral vector to transfer the vasopressin receptor gene from the monogamous species into the polygynous species.
With this change in a single gene, the polygynous species essentially becoming monogamous.