Summary: Life History Evolution

Read the summary and the most important questions on Life history evolution

• 1 Lecture 1

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• Evolutionary Ideal Organism

  - Darwinian Demon
  

  • Reproduce at birth
  • Unlimited reproduction
  • Live forever 

  - Every animal has to maximize its fitness/reproductive output
  -With the darwinian demon there are no limitations  such as intrinsic and extrinsic fitness 

• Life history theory

  - Allocation of finite time and energy to fitness components
  - Trade-offs
  - Optimize combinations of traits to maximize fitness

• Intrinsic factors (limiting (within body))

  - Physiological constaints
  

  • something in you limits you to not produce more offspring

  
  - Anatomic constaints (body mass)
  

  • trade-off many eggs&small or less eggs&big

  - Reproductive 'schedule' 
  

  • body needs certain foods from environment

  - Longevity

• Hunting re-shapes life history

  Moms with cubs are not hunted -> Results in cups staying longer with the mother (strong selection) ->  
  - The cubs are a safety armor for the mother 

• Pace of life history

  Fast/Slow
  Development: +/-
  Lifespan: -/+
  Juvenile mortality: +/-
  Reproductove events: -/+
  Offspring per event: +/-
  Parental care: -/+
  
  Fast = r 
  Slow = k

• 2 Lecture 2

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• Clutch size and litter variation

  - Variable across and within species
  - Optimization of individual fitness
  - Adjustment to environmental conditions   

• Optimal clutch size

  - Produces the highest number of viable offspring
  - Not always the biggest is the best
  - There is always an optimally curve
  

  • Intrinsic factors (-trade offs)
  • Extrinsic factors (-temporal variation) 
  • Parenting-offspring conflict (offspring are gonna try to be the only offspring)
  • parasitims

  
  
  - The clutch size of each species is a product of natural selection which favours the largest number of offspring that parents can provide care for  

• Clutch/litter size

  Proximate factors
  - Temperature
  - Day length
  - Resources availability
  Ultimate factors
  - Genetics (heritability)
  - Natural selection (Lack's principle)

• Offspring survival and recruitment curves

  Survival curves can be related to clutch size
  

  • symmetrical or asymmetrical

  Hole-nesting bird in temperate area
  

  • very small clutches: low survival rate
  • no difference in intermediate clutch size
  • sharply lower survival rate large clutches 

• George Williams - William's principle

  - Lack's principle "refined"
  - The effort spend on reproduction must be worth the cost, compared to the long-term reproductive fitness of the individual
  
  - A given amount of reproductive effort at one age should make a parent's future reproductive effort smaller than it otherwise would have been. The difference is the cost of reproduction