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?
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Very costly behavior
- vulnerable to predation
red shouldered hawk
Sibling aggression and siblicide
Occurs when resources are variable or in short supply?
Offspring compete for resources (they only share 50% of genes)
have two eggs, often raise two young
have two eggs, first hatched chick always kills second chick
Selection may act on parents and offspring differently.
Some actions that increase fitness of offspring may reduce fitness of parents.
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.
Honest signals of quality in offspring?
Haplo / diploid organisms (like ants, bees and wasps)
fertilized egg = female ; un-fertilized egg = male
Temperature Dependant Sex Determination (TSD)
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
Leads to overlapping generations
Key step in the evolution of sociality?
Monogamous, male parental care
polygynous, no male parental care
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.