Lecture 22

Question 1

Define aging/senescence

Answer 1

The progressive decline in somatic function reflected in Reduction in fertility and survivorship

Question 2

What is the proximate cause as to why aging/senescence occurs? What two things does it cause?

Answer 2

The progressive degradation of soma causing impaired function and increased disease

Question 3

What is the Proximate Theory of Aging? How is it combated against?

Answer 3

The theory suggesting that soma are destroyed due to oxidative metabolic process in the body that make high reactive free radicals that damage macromolecules and ultimately the soma

Humans naturally make bilirubin and intake of vitamins (E and C) can decrease radical formation but it is not enough to provide sufficient repair for increased longevity

Question 4

Trade offs affect three things

What tradeoffs occur for allocating resources to DNA repair and reproduction?

Answer 4

Display size (morphological traits) 
Foraging rate (behavioural traits) 
Longevity, aging (life history traits) 

DNA repair:
(+): longevity, (-): fecundity

Reproduction rate:
(+) reproductive rate, (-): longevity

Question 5

What was the conclusion to the waterstridee trade off study where reproductive rate was manipulated and # of offspring was measured to determine if a trade off was at play?

Quickly describe the results

Answer 5

A trade off is at play as the longevity of waterstriders is decreased as more resources are allocated to making offspring—no individual can both live long and produce many

The more eggs one produced the shorter their lifespan

Question 6

Sex differences in aging

What factors reduce male/female survival?

Answer 6

Females typically outlive males

Males: aggression and risk taking
Females: high birth rates

Question 7

Theories of Senescence (2)

What concept do the two rely on?

Answer 7

Mutation Accumulation Theory (deleterious mutations w age-specific effect that accumulate and become present/active later in life)

Antagonistic Pleiotropy Theory (genes w beneficial effects early in life are favoured despite carrying the possibility of later-life negative effects)

Both rely on the fact that the strength of selection decreases with age

Question 8

Explain Mutation Accumulation Theory using examples for early-acting and late-acting diseases

Answer 8

Early-acting (pre-reproductive): ex. Tay Sachs Disease patents don’t live past 4 years old so they don’t live long enough to reproduce -> selection is strong and patients die before passing genes on

Late-actin (post-reproductive): ex. Huntington’s Disease patients usually diagnosed at 30-40years old and have already reproduced -> selection is weak and patients have a 50% chance of passing genes on

Question 9

What was the conclusion to the fly longevity elongation study where reproduction timing was manipulated and longevity observed to determine if antagonistic pleiotropy was occurring?

Quickly describe the results

Answer 9

Antagonistic pleiotropy was at work as longevity was increased when late-reproduction was made more important but at the cost of early-life fecundity

Saw an increase in longevity when late life fecundity increased