genetic diversity and natural selection Flashcards
what is genetic diversity
the number of different alleles of a gene in a population
what are 2 things that can increase genetic diversity in a population
mutations in the DNA forming new alleles
different alleles being introduced to the population via migration
what is a genetic bottleneck
an event that causes a big reduction in a population
what are the effects of a genetic bottleneck
it reduces the number of different alleles in the gene pool and reduces genetic diversity
the survivors reproduce and a larger population is created from few individuals
what does genetic diversity allow
genetic diversity allows natural selection to occur
what is natural selection
when the allele codes for a characteristic that increases the chances, its freauency within the population can increase
what are the 3 types of adapation
behavioural
physiological
anatomical
what is a behavioural adaptation
the way an organism behaves that increases it chance of survival e.g a possum playing dead
what is a physiological adapatation
process inside an organisms body that increases it chance of survival e.g hibernation
what is a anatomical adaptation
strucutral features of an organisms body that increase its chance of survival e.g whales thick layer of blubber
what is an adaptation
a feature that helps an organism to survive in their enviroment
what are the two types of selection
directional
stabilising
what is directional selection
where individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce
what is stabilising selection
where individuals with alleles for characteristics towards the middle range are more likely to survive and reproduce
when does directional selection occur
in response to an enviromental change
