Parental Care

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Parental Care

• Females typically show parental care
• Female is already heavily invested
• Paternity uncertainty am I really the father?
• Males loose mating opportunities

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Exceptions Male Parental Care

• Fish males often tend eggs and fry
• External fertilization ensures paternity
• Males may guard several clutches of eggs
• Presence of eggs is a signal to other females of
  his willingness to be a good parent
• Females also spend a lot of energy producing eggs
  so they need to forage

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Three Examples

• Randalls Jawfish is a mouth brooder able to do
  only one clutch at a time
• Male stickleback tends more than one clutch
• Flathead minnow takes over another males
  territory, and adopts 50 of the clutch to show
  hes a good father

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Cost Benefit Analysis

• Two male phenotypes parental and deserter
• Assume paternity is 40, parental father has 2
  clutches of 10 eggs each, deserter has 5
• Survivership is 75 for parental males, and is
  30 for deserters
• Which father is more successful?

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Water Bugs

• Female lays large eggs on the back of the male
  mate
• He may have room for more than one clutch, and
  eggs present are attractive to females as they
  signal his good intentions

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The Egg Problem in Water Bugs

• Must move carbon dioxide out of egg and oxygen
  into it
• Best accomplished in the atmosphere
• Eggs will desiccation without water
• Male does a balancing act keeping the eggs wet,
  but exposing them to the atmosphere

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Why Not Lay a Smaller Egg?

• Water bugs are among the largest of insects and
  they feed on frogs and fish
• Insects are limited to 5 or 6 molts (instars)
• Each molt increases size about 50
• To be big the egg has to start big

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Why Do The Males Do The Parental Work?

• Producing the large eggs by the female requires a
  lot of food and time spent foraging
• Carrying eggs would limit foraging time
• Male can do two clutches, so his sacrifice is not
  that great

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Forms Of Parental Care

• Construct nest, burrows and establish territories
  (mating effort and parenting)
• Produce different size gamatesAltricial species
  (passerines)10g egg, Semi-altricial (hawks,
  owls)38g egg, Semi-precocial (gulls, terns)48g
  egg, Precocial (quail, ducks)80g egg

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Care of Eggs

• Protect laying site
• Carry eggs around (water bugs) penguins hold
  their egg on the top of their feet
• Retain eggs in reproductive tractviviparity
  (snakes and lizards)

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Penguins
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Increasing Levels of Care

• Protect young without feeding (fish)
• Provision young prior to birth Mud dobbers, the
  placenta in mammals
• Provisioning young after birth Regurgitation of
  food, production of specialized food (mothers
  milk)
• Social Assistance to mature offspring Vervet
  Monkey.68 offspring with mom present, .30 if
  shes not

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Discriminating Parental Care

• Mexican free-tailed bats have up to 4,000 bats
  per square meter
• Mom goes out foraging at night
• Returns and recognizes offspring by smell and
  auditory mechanisms
• About 80 accurate

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Ecological Conditions and Discriminating Parents

• Cliff swallows are colonial, living in large
  aggregations
• Non offspring often in the nest
• Chicks make a complex call that parents recognize
• Barn swallows are not colonial
• Chicks make only simple calls

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Male Bluegill Parental Care

• Large male guards nest females spread eggs on the
  nest
• Sneaker males slip in between male and female
  pair to deposit sperm
• Males are sensitive to the sneakers in their
  parental behavior

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Aggression against a pumpkinseed sunfish predator
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Adoption of Non-Genetic Offspring

• Cost Feeding non-genetic chick decreases
  benefits to genetic chicks
• Benefit Incorrect rejection of genetic chick is
  avoided
• Must be a relatively infrequent event, otherwise
  parents would have evolved more effective
  discrimination mechanisms

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Brood Parasites

• Cowbirds and cuckoos use this non-parental form
  of raising chicks (benefit)
• Cost Brood parasite parents choose the
  parasitized nest carefully and must time their
  egg laying appropriately
• Cost Check the nest to make sure the resident
  pair has not rejected the chick

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Brood Parasites Success

• Parasite egg hatches first
• Parasite chick is larger than host chick
• Parents feed the highest mouth

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Costs and Benefits of Being a Host

• Cost Time and energy to raise the parasite
• Cost Recognition errorstoss out own eggs
• Parasitized small species not big enough to
  throw-out the foreign egg
• Abandon nestFind a new one, build a new nest,
  lay a new clutch

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Costs and Benefits

• Suitable nest sites for birds abandoning their
  parasitized nest may be limited, so making the
  best of it may be the only way to reproduce

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Mafia Hypothesis

• Cucoos keep watch over the nests they have
  parasitized, and parents who dispose of the egg
  of the cuckoo will experience the vengence of the
  cuckoo

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Parent-Offspring Conflict Robert Trivers

• Offspring 1 is related to itself r1.0
• Offspring 2 is related to sibling 1 r.5
• Parents are related to their offspring r.5
• Offspring 1 gains more fitness by having parents
  give him extra care rather than the sibling,
  offspring 2
• Parents fitness is the same for 1 and 2,
  therefore care should be equal

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An Example of Parent-Offspring Conflict

• Two offspring raised to maturity will each
  produce 3 offspring
• One offspring raised to maturity (other is gone)
  at maturity can produce 5 offspring
• The math 3X.51.5, 3X.25.75 total fitness for 2
  offspring2.25 for each of the offspring
• Fitness for a single offspring 5X.52.5
• Parents 2 offspring3.5, 1 offspring2.5

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Parental Favoritism

• Parents sometimes produce more offspring than
  they can raise
• Brood reduction is a mechanism to solve this
  problem
• Mechanism of brood reduction is either parental
  favoritism, or siblicide

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Siblicide

• Great white egrets show siblicide
• Lay clutches of 3 or 4 eggs and siblicide is
  almost inevitable in 4 egg clutches (85) and not
  uncommon in 3 egg clutches (35)
• Parents do not interfere with siblings behavior

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Mechanisms of Siblicide

• Eggs are laid and hatch asynchronously with and
  average of 1.5 days between
• Alpha chick has a size advantage over beta and so
  on
• Parents feed chicks a partially digest bolus of
  fish
• Chicks scissor on the parents beak causing
  regurgitation of the bolus

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• The bolus is monopolizeable
• Subordinate chick gets beat-up to keep him out of
  the way
• Blue Herons also show brood reduction, but not
  via siblicide
• Egrets cross-fostered to heron parents continue
  to show siblicide
• An obligate effect, apparently

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Preferential Feeding by Parents

• The tallest, loudest, most colorful chich get
  better care
• Redness of the mouth in lark bunting, for example

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Experimental Manipulation of Coloration

• Rinse mouth of chick with either red food
  coloring, yellow food coloring or water
• Measure number of feedings received

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Olive Baboons at White Rocks Shirley Strum
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Communication Among Baboons

• Eye flash Threat
• Yawn Threat (showing teeth)
• Tail up Fear
• Grunts Pleasure
• Grimace Pleading
• Screams Aggression/fear

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Social Grooming

• Reassurance
• Make friends, win favor
• Calming effect

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Parent-Offspring Conflict

• Rama wants to ride, but mom wants to conserve
  energy during the drought
• Dawa wants to nurse, his mother want to wean him

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Coalitions and Friendships

• Dominant males deal with the juvenile Moon
• Moon is friends with younger baboon and uses it
  as a shield in aggression situation
• Moon is also friends with the mother

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Social Rank

• Dominant mom Head start for dominant offspring
• Older dominant females a source of knowledge
  about foraging
• Moon cannot move up the dominance hierarchy in
  his troop, so must leave

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Inter-Group Conflict

• Females are aggressive between each other
• Males punish females who get too close to rival
  troop