Transcript 25_ParentalCare2

Announcements
Parental care
Very costly behavior
- time
- energy
- vulnerable to predation
emperor penguin
red shouldered hawk
earwig
tarantula hawk
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)
Galapagos
masked booby
blue-footed booby
have two eggs, first
hatched chick always kills
second chick
have two eggs, often
raise two young
Parent offspring conflict (Trivers)
Selection may act on parents and offspring differently.
Some actions that increase fitness of offspring may reduce
fitness of parents.
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
Parental favoritism
Honest signals of quality in offspring?
barn swallows
Asynchrony in hatching (birth order) can promote or reduce
sibling conflict and parental favoritism
great egret
Can parents control sex of offspring?
Seychelles Warbler
Can parents control sex of offspring?
Haplo / diploid organisms (like ants, bees and wasps)
fertilized egg = female ; un-fertilized egg = male
Temperature Dependant Sex Determination (TSD)
many reptiles
Helpers at the nest
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
Helpers at the nest
Leads to overlapping generations
Key step in the evolution of sociality?
Genetics basis for mating systems / parental care.
prairie voles
Monogamous, male parental
care
meadow voles
polygynous, no male 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 became monogamous.