L14 parent-offspring conflict

What are the main types of family conflict

sibling rivalry sexual conflict between parents parent offspring conflict

What causes parent offspring conflict

parental overproduction of young

What is sibling rivalry

competition between siblings for limited resources

Why do parents overproduce offspring

to cope with unpredictable environmental conditions

What is resource tracking

producing more offspring than needed in case conditions allow survival

What happens in a good year for offspring

extra offspring survive

What happens in a bad year for offspring

extra offspring die

What is the brood reduction hypothesis

brood reduction increases fitness when food is scarce

Who proposed the brood reduction hypothesis

David Lack

Why might parents produce extra offspring as insurance

to account for infertile eggs or failed hatching

What are examples of developmental failure in offspring

infertile eggs eggs that do not hatch abnormal young

How can extra offspring act as a resource

through siblicide and cannibalism

What is the problem of feeding in broods

limited resources may not support all offspring

How many units of food are needed for chick survival in the example

ten units

What happens if all chicks are fed insufficiently

all may die resulting in no offspring

What is the advantage of early brood reduction

some offspring survive instead of all dying

What should natural selection favour in brood size

mechanisms that reduce brood size early

What is asynchronous hatching

eggs hatch at different times

What is synchronous hatching

eggs hatch at the same time

What causes size hierarchy in broods

asynchronous hatching

What is the advantage of being first to hatch

larger size and competitive advantage

What happens to the smallest chicks in asynchronous broods

they are more likely to die

How do female blackbirds control brood size

by laying order and incubation timing

What did Magrath experiment manipulate

brood synchrony

What was measured in Magrath experiment

number of juveniles surviving after fledging

What happened in wet conditions in Magrath study

synchronous broods performed well

What happened in dry conditions in Magrath study

asynchronous broods performed better

What did feeding chicks in dry conditions show

food availability determines success

What pattern was seen in American kestrels observational data

poor food leads to more brood asynchrony

What pattern was seen in good food conditions in kestrels

less brood asynchrony

What happened when kestrels were given extra food

clutch size unchanged but hatching spread reduced

What is the size hierarchy in herring gull chicks

A largest B intermediate C smallest

Which chick usually dies in herring gull broods

C chick

What happens to B chick after C dies

food intake increases

What happens to A chick after C dies

food intake remains the same

What does this show about parental care

dominant chicks already receive most resources

What did egret experiments show about brood reduction

it does not always increase food per chick

What happens to feeding rate when brood size is reduced in egrets

feeding rate per chick stays the same

What is the purpose of extra offspring in blue eyed shags

insurance if earlier eggs fail

What determines survival of the third chick in blue eyed shags

success of first two chicks

What is obligate siblicide

guaranteed killing of one sibling

What species shows obligate siblicide

black eagle

Why does siblicide occur in black eagles

older chick attacks younger regardless of food supply

What is the likely function of the second egg in black eagles

insurance

What is an example of extra offspring used as food

sand tiger shark

How do sand tiger shark embryos compete

they eat each other in the womb

What remains after embryo competition in sharks

one large surviving offspring

Why do sand tiger shark embryos have teeth early

to enable cannibalism

What additional food source do shark embryos receive

unfertilised eggs provided by the mother