genetic diversiry and adaptation Flashcards
what is genetic diversity
number is different alleles of a gene in a population
how is genetic diversity a factor enabling natural selection
new allele of a gene may benefit a possessor
results in a change in the polypeptide coded for that positively changes urs properties
giving the possessor a selective advantage
what is evolution
change in allele frequency over many generations in a population
occurs through natural selection
what are the stages of natural selection
- mutation - random gene mutation resume in new alleles of a gene
- advantage- in certain environments the new allele may benefit it possessor, selective advantage
- reproductive success- possessors more likely to survive so increased reproductive success
- inheritance- advantageous allele inherited by offspring
- allele frequency- over many generations allele increases in frequency in population
MARIA
what is an anatomical adaptation and example
structural / physical feature that increases survival
thick layer of polar bear - keep warm in cold climates
what is a physiological adaptation and example
processes / chemical reaction inside organisms increasing survival
lowering rate of metabolism during hibernation - conserve energy
what is behavioural adaptation
way in which an organism acts that increases survive
playing dead - avoid predators
what are the two types of selection
directional - exemplified by antibiotic resistant bacteria
stabilising - exemplified by human birth rate
what is directional selection
who has selective advantages - organisms with an extreme variation of trait eg. bacteria with high resistance to an antibiotic
change in environment-yes
effect in population
- increase frequency of organisms with extreme trait
- normal distribution curve shifts towards extreme trait
draw a normal distribution cure for directional selection
upside down u
population after selection is shifted right
what is stabilising selection
who has selective advantage- organisms with an average/ modal variation of a trait eg. babies with an average weight
changes in environment- no usually stable
effect in population
- increased frequency of organisms with average trait
- normal distribution curve similar but less variation around mean
draw a distribution curve for stabilising selection
thinner upside down u more in the middle
what type of selection is selective breeding and why
directional selection
alleles resulting in particular extreme characteristics are favoured
