Populations and evolution Flashcards
name three things that cause genetic variation
meiosis
mutations
random fertilisation of gametes
what are selection pressures
The environmental factors that
limit the population of a species
what is the gene pool
variety of alles for a gene within a population
what is continuous variation
when individuals in a population
vary within a range
what is discontinuous variation
when there are two or more distinct categories
what is continuous variation controlled by
it is controlled by many genes
and can be influenced by environmental factors
what is discontinuous variation controlled by
it is controlled by one gene
what is evolution
a change in allele frequency over time
what two processes drive evolution
genetic drift
natural selection
what are the three pressures that limit the chances of an organisms survival
predation
disease
competition
outline natural selection
there is variation in phenotype between individuals
individuals with benefical phenotype are more likely to survive
thery reproduce and pass on their genes to their offspring
there is an increase in frequency of the advantagous allele in the population
what are the three types of selection
stabilising
directional
disruptive
what is stabilising selection
where individuals with alleles for phenotypes towards the middle of the range are more likely to survive and reproduce
outline variation within a population
members of the same species have the same genes but different alleles
this results in variation so some individulas are better adapted to the selection pressures
what is directional selection
where individulas with alleles for a single extreme phenotype are more likely to survive and reproduce
