Flashcards in Evolutionary Medicine (TEST 3) Deck (31):
Application of evolutionary history to study present day diseases
what is more important: the why or the how- in evolutionary medicine?
the WHY not the HOW they get sick
What are the two uses of evolutionary medicine?
-To understand disease processs
-To create effective treatment
What are three other modern applications of evolution?
3) computer science
What is the MAIN purpose of evolutionary medicine?
to understand causes and persistence of disease
Enviroment of Evolutionary Adaptedness
if environments change rapidly, organisms may not be adapted to altered conditions; adaptations useful in previous conditions cause medical problems under altered condition
decline in fertility & survival late in life
What are the three main hypothesis for the evolution of aging;
as we age, disposable soma deteriorates
Support for Irrepairable damage hyp?
males senesce earlier than females in species under
intense intra-sexual selection
Argument against Irrepairable damage hyp?
metabolic rates do not correlate with lifespan in mammals e.g., bats (high metabolic rates) do not live shorter lives - assumes that selection cannot improve mechanisms to repair damage (e.g., assumes there is no genetic variation for repair efficiency) and predicts that lifespan cannot be
selected on, contrary to results of selection experiment
Less selection later in life so deleterious mutations become more prevelent
Is their heritable variation in aging?
The observation that there exists heritable variation in longevity (i.e., selection can lengthen lifespan) weakens the Irreparable Damage Hypothesis for senescence
Intensity of selection on late-acting genes declines because of what two reasons?
(a) they affect fewer individuals in a population
(b) they are already passed on before they act
mutations with strong positive effects early in life AND negative effects late in life can be selected for (trait has a positive and a negative phenotypic effect, and the two effects occur at different times)
multiple phenotypic effects caused by single gene
Which Hypothesis have the most support?
1 and 2
Measure of fitness impact of pathogen/parasite on host (**** function of the interaction between host and
viral disease of rabbits cause by myxoma virus acute conjunctivitis and blindness secondary bacterial infections (e.g., pneumonia) death within about 5-15 days
Why did they introduce the myxoma to australian rabbits?
For species control (there were too many)
What could we predict would happen evolutionarily in the rabbit case?
1. evolution of resistance in rabbits
2. evolution of reduced fitness-impact of virus
Which happened in the rabbits and why?
Reduced fitness-impact of virus because the Myxoma virus is transmitted via a vector (mosquito) and tradeoff occured
host survival vs. colonization rate (if it takes a long time to colonize the virus more hosts start surviving)
What is the effect in a low virulence virus?
Low infectivity - High host survival (= high host longevity when sick)
High Virulence Viruses
- High infectivity - Low host survival (= low host longevity when sick)
parasite/pathogen fitness is determined by the survival/reproduction of the current host.
•Reproductive interests of parasite and host are aligned
•=> low fitness-impact tends to evolve
parasite/pathogen fitness is determined not only by the survival/reproduction of the current host, but also by the number of new hosts colonized.
•Reproductive interests of parasite and host are NOT aligned.
•=> high fitness-impact tends to evolve
What are the three ways virulence evolves?
2) Lateral Vs. Vertical Transmission
3)Number of pathogen strains
What is the deal if you have a single infection in host?
There are no competitions between strains so virulence is maintaned
What is the deal if you have multiple infections?
Competition between the strains results in a selection for high virulence