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