Flashcards in BIO220 Lecture 6 Deck (37):
What is the ultimate question when it comes to aging?
Why did aging evolve?
What are some ways to increase lifespan?
1. Eat ACE vit
3. Diet restrictions
what does vit E do?
Increase lifespan (maybe?)
What does exercise do?
Reduce heart disease
What does diet restrictions do?
eating less = live longer
How does money impact aging?
More wealthy = live longer
Molecules with at least 1 unpaired electron
What do free radicals do?
Attack & modify macromolecules
Oxidation of DNA, lipids, proteins
-> Damage body and speed up aging
How do we defend against free radicals?
some AA act as antioxidants
What can act as antioxidants?
Some AA in the body
Vit E and C
Ideal organism that can maximize every component of fitness without constraints
What does the Darwinian Demon prove?
Nothing can do that, so there must be constraints / trade-offs for biological systems
Tradeoffs happen between...
Display size / morphological traits
Foraging rate / behavioural traits
Longevity / life history traits
Display size is a ____ trait
Foraging rate is a ____ trait
Longevity is a ____ trait
Cost of high reproductive rate
Accelerates senescence (die earlier)
Why does high reproduction shorten life-span?
A lot of effort, time, resources used for reproduction that can otherwise be used to maintain body
How was the hypothesis that high reproduction shorten life-span tested?
Manipulate food supply to control reproductive rate.
Those who laid more eggs lived 1/2 as long as those who didn't lay many eggs.
What is the order in which reproductive senescence occurs?
1. Eggs fail to hatch
2. Eggs fail to develop
3. Reproduction stops
What type of quality of eggs in waterstriders can be seen as they get older?
1. Developmentally arrested
2. Abnormally developed
What are some methods of measuring cost of reproduction?
- Diet restrictions
- Egg addition (give more eggs to some mothers)
- Removal of oviposition sites (can't lay eggs)
- Delay of reproduction (select for these types)
What were the results of the genealogical study done on British aristocracy?
Mothers before 1700 had 2.8 offspring, and had higher probability of death every year.
Mothers after 1700 had 2.0 offspring, and had lower probability of death.
Age of death decreased with increasing number of offspring.
What is an alternate explanation for the genealogical study done on British aristocracy?
Better sanitation and medical care after 1700
Why do female mammals typically outlive males?
Cost of male competition
What are the 2 theories of senescence?
1. Mutation accumulation
2. Antagonistic Pleiotropy
What does MA and AP have in common?
Relies on the assumption that strength of selection declines with age
Bad mutations with age-specific effects that don't happen until you're older. Natural selection can't act on this b/c you have already reproduced, so no point.
Pleiotropic genes that have pos effect earlier in life will be selected for despite it having neg effects later in life
Even in a population without senescence, survival probably decreases with age because...
External factors (predators, accidents, parasites).
10% externally imposed mortality per year
Why does selection strength decrease as you get older?
1. Offspring already has that disease, so no point in selection
2. Many individuals die before expressing
Evidence for MA?
Single gene effects:
1. Severe diseases that are present pre-reproduction = 7%
2. Severe diseases that are present post-reproduction = 93%
How was cost of reproduction tested for in fruit flies? (Michael Rose)
Normal fly which reproduces lived shorter lives than those that were manipulated to reproduce less
What was the result of Rose's experiment in terms of breeding for longevity?
O lines lived longer than N lines (both males and females)