💜 3.4.4 genetic diversity and adaptation Flashcards
(13 cards)
What is natural selection a mechanism for?
It is a mechanism for evolution
What is genetic diversity?
It is the number of different alleles of genes in a population
What is genetic diversity a factor of ?
A factor enabling natural selection to occur
What does natural selection result in?
It results in species that are better adapted to the environment
What are the three categories of adaptations?
- physiological
- Anatomical
- Behavioural
What is the mnemonic to remember the principles of natural selection in the evolution of populations ?
Viscous - variation
Monkeys - mutations
And - advantageous allele
Snakes - selection pressure
Seldom - survival
Rip - reproductive success
People - passed
Apart - alleles
What are the principles of natural selection in the evolution of populations (paragraph) ?
Variation is already present due to mutations, these can produce advantageous alleles which can be selected for selection pressure in increasing survival success and increasing reproductive success so these alleles are passed to increase in frequency of these alleles.
How many types of natural selection are there (year 12 only)
Two types of natural selection
What are the two types of natural selection called?
Directional and stabilising.
What is stabilising selection?
This is where alleles for the main value of the characteristic are selected for and alleles for the extreme values are selected against.
This occurs in an unchanging environment
What is directional selection?
This is where alleles for one of the extremes for a characteristic is selected for. It occurs in a changing environment.
What is the example for directional selection?
The example for directional selection is antibiotic resistance in bacteria.
If antibiotics are being used, the alleles for antibiotic resistance will be selected for and, very quickly, its frequency will increase in the bacteria population.
What is the example for stabilising selection?
An example of stabilising selection is birth weight.
Alleles for small babies are selected against as small babies have a large surface area to volume ratio so heat is lost quickly – thus struggling to maintain their body temperature.
Alleles for large babies are selected against as large babies have trouble being born as their heads are too big.
