Ageing

Question 1

What is ageing?

Answer 1

Ageing id the progressive physiological change in an organism over time that result in a decrease in intrinsic ability to survive and reproduce, and an increase in health problems.

Ageing is a universal process, caused by asymmetrical division of stem cells: one is a disposable somite which growth rate decrease over time, one is an immortal germline.

There is a huge difference in life span in animals, and a large variation in age-related health problems.

Question 2

What is meant with life history?

Answer 2

Life history explain inter- and intraspecific variations in the characteristics of the life cycle:

• longevity
• developmental time
• reproduction age
• body size
• number of offsprings

The principles behind it are:

• internal and external mortality
• high intrinsic mortality
• changes in extrinsic mortality
• resource acquisition and allocation
  
  • Y-model = different strategies on how to divide limited resources in space and time == trade-off

Question 3

What mechanisms of life history?

Answer 3

1. selection shadow
   selection acts on reproduction; as reproduction rate decrease over time, the force of selection will reproduce as well
2. mutation accumulation theory
   weak selection at older ages, will be insufficient to remove deleterious mutations from the population
3. antagonistic pleiotropy
   genetic/physiological mechanisms has multiple effects on trait = trade-off between life-span and reproduction
   
   • energy trade-off = disposable soma theory
     balance of energy between reproduction and ageing
     optimal fitness achieved at a level of repair lower than needed for immortality
   • functional trade-off = developmental theory of ageing
     gene expression optimized for development and early life reproduction

Question 4

What is meant by genetic architecture?