Unit 3 Mating and Parenting

Chapter 12 Parenting

Success

• Success is measured by # of young that survive into adulthood and reprod themselves as well

4 Factors led to the evolution of parenting:

• 1. Saturated habitats- more crowded, more parenting

• 2. Harsh/stressful environ- need parents or young will die

• 3. Specialized diet- learn what to eat

• 4. Predation pressure- young need protection

Who needs parents?

• More complex animals take longer to develop and need more parenting

Conflict between parents may arise when:

• 1. Less fathering when male not sure child is his, but female always knows its hers

• 2. Internal fertilization leads to more female care, external- male b/c they are more certain

• 3. Proximity- female more likely near young when they hatch

Conflict between parents and offspring

• Cost/benefit analysis

• Parents want to max their reprod success

• At some point they need to allocate their resources or move on altogether

Parenting variations• Little parental care

needed when young are precocial (born fully developed)

• Ex: turtles, hares, large grazing mammals

• Lots of parental care needed when young are altricial (born before development complete)

• Ex: primates, many birds

Little parenting

• Lay eggs and leave• Young fend for

themselves once born

• Larger bird eggs allow for more dev’t before birth

Ample parenting

• Animals that live in colonies

• Young born naked and helpless

Nesting behavior

• Nest- structure for rearing young

• Greatest variety in birds• Protection via location,

camouflage, inaccessibility

• Incubation by body or materials

• Chicks have “egg tooth” to chip out

• Parents remove shell from nest

After hatching

• Imprinting- genetically driven

• Young will imprint on large object moving near them during a critical time window, most likely mother

• Necessary for survival• FAP- fixed action

pattern (instinct)

The most parenting

• Mammals• Milk from female for

nutrients• Gestation varies-

marsupials shortest• Long learning

process for young b/c survival depends on it

Tutoring and Play

• How to hunt• Skills practiced by

playing• Develop social skills

and sexual behaviors required for survival

Group parenting

• More models for young to imitate

• Constant adult supervision

• Group bonds are strong

• Mothers are very protective

• Ex: wolves, lions

Unusual parenting strategies

• Unusual brooders- frogs hatch eggs out mouth, seahorse males give birth out pouch

• Brood parasites- birds lay eggs in another’s nest, nesting bird cares for all young not knowing

• Ex: cuckoos and cowbirds

Infanticide and cannibalism

• Killing of young• Usually a new male

will kill young of previous male

• One young receives food, other starves

• Older young harass younger

Why have more than one?

• Insurance• If one dies, you still

have another left• Food supply• If there is lots of food,

more young can survive.

• Less food, parents must allocate resources

Natal dispersal

• Mov’t from birth place to place for first breeding

• Distance differs by gender

• Males usually leave• Females tend to stay

closer, more relatives around help raise young