Unit Four: Nurturing a Family Unit Chapter 11: Parenting Decisions.
Unit 3 Mating and Parenting Chapter 12 Parenting.
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Transcript of Unit 3 Mating and Parenting Chapter 12 Parenting.
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