Diversity and Adaptations Flashcards
What is genetic diversity?
the number of different alleles within a population
what is natural selection?
the gradual increase of an advantageous allele in a population’s gene pool over time
Describe the process of natural selection.
- random mutation occurs to produce a type of allele
- selection pressure is introduced
- those with the advantageous allele survive and reproduce
- those without die
- this means that only those with advantageous allele can pass on their gene to the next generation so the population overtime become resistant to the selection pressure
the frequency alleles of the gene pool change over time
What is the overall result of natural selection?
the population becomes better adapted to their environment
What are the types of adaptations resulting from natural selection?
- anatomical
- physiological
- behavioural
What is an anitomical adaptation?
physical adaptations
either internal or external
What is an physiological adaptation?
processes inside the body that increase chances of survival
What is an behavioural adaptation?
changes in behanviour that increase chances of survival
What are the types of selection?
- directional
- stabalising
What is directional selection?
when there is environmental change so those with the phenotype best suited for the new environment are most likely to survive
Describe directional selection.
- there is an environmental change
- a random mutation occurs so an organism effected by the change becomes immune
- they survive and pass on their immune gene to their offspring
- this changes the allele frequency so there are a higher amount of organisms with this gene than not (they eventually die off)
What does a directional selection graph look like?
- the disribution curve favours the extreme values so
- the maximum point isn’t in the middle (left or right side of the x axis)
What does a stabalising selection graph look like?
- the maximum point of the curve is in the middle
- distribution curve favours mean
What is stabalising selection?
When something other than an environental change causes those with the favourable gene to be preserved an the other to reduce
Describe stabalising selection.
- a non-environmental change occurs
- random genetic mutation happens making some organisms better suited to change than others
- this changes the allele frequency so those closest to the mean are favoured
