Lecture 3c - Intelligence And Fitness: The Problem Of Mutation Accumulation Flashcards
Name 5 possible causes of mutations
Radiation - gamma radiation, X-ray or cosmic rays
Chemical damage - oxidants in the body
Toxins from the environment
Drugs
* genetic replication is imperfect, errors can occur
Are the majority of mutations harmful? If so I what way?
Yes, they are. Some are lethal and remove themselves and remove themselves from the genetic pool
They damage your reproductive success
What controls the inheritance of mutations? Which mutations are most often passed on?
Controlled by natural selection
The mutations that are not lethal but mildly deleterious because they don’t select themselves out by killing/ inhibiting the carriers reproduction.
Are mild deleterious never removed from the gene pool?
No they are, it just takes a lot longer to do. Because it’s gradual because their carriers have less offspring rather than no offspring
How many of these mildly deleterious mutations do humans pick up each generation?
Approx 3. But also about 100 other mild mild mutations
Meaning that the new mutations reduce the genetic quality and fitness by 3%
What is an alternative name for purifying selection?
Mutation selection balance
Or
Negative selection
What is purifying selection ?
Removing spontaneous mutations
What two ways does natural selection severely limit the reproductive success of individuals with large amounts of mutations?
1) by ensuring they don’t survive to reproductive maturity, so they may die in the womb, or infancy. Or by having shortened adult lives. Or being infertile.
2) through competition. They are less likely to be chosen to be mates (sexual selection)
What is a good analogy for the power of natural selection against mutation selection balance?
Why?
Walking up the down escalator
The constant addition of new mutations each generation is the equivalent of the down escalator and natural selection clearing them away is the equivalent of going up the escalator
Describe the analogy in terms of walking slowly up the escalator…
Natural selection is weak, the number of mutations is steadily increasing and the species moves closer to reproductive 0 and extinction
Describe the escalator analogy in terms of walking up at the same pace of the escalator going down…
Perfect mutation selection balance, as the new mutations come in, natural selection wipes out the old ones
Describe the escalator analogy In terms of running up the down escalator…
If natural selection provides an adaptation for a species which allows for improved reproductive success, then natural selection is stronger than the mutation accumulation.
Why is intelligence especially sensitive to mutations?
‘G’ intelligence is argued to be the quality of the brain. Because 50% of mutations effect the brain because it is a large mutational target.
It’s a target because things like, structural proteins, enzymes, hormones and NT which all involve lots of coding effect the brain.
Because intelligence is sensitive to the number of mutations, what is it a good indicator of ?
Fitness indicator
If intelligence is a fitness indicator, what would high intelligence signal to a prospective mate?
That the genome of that individual does not contain many mutations
