module 6: variation Flashcards
continuos
individuals in a population vary within a range- mono distinct categories
height
discontinuous
two or more distinct categories and individuals fall into one
blood group
epistasis
the allele of one gene masks the expression of the alleles on other genes
what is evolution
the change in allele frequency in a population over time
natural selection
individuals in a population vary because they have different alleles
predation, disease, competition create struggle for survival
some better adapted bio pressures
those with advantageous alleles survive, reproduce, pass on allele
more of next generation inherit advantageous allele
genetic drift
chance determines passing on alleles, certain alleles passed on more than others
genetic bottleneck
event that causes big reduction in population size do reduced gene pool
founder effect
when a few organisms in a population start a new population with small number of alleles
artificial selection
humans select desirable traits to breed
speciation
development of a new species, populations of same species become reproductively isolated
allopatric speciation
geographic isolation with different conditions on each side and natural selection to the environment cause it
how does reproductive isolation occur
seasonal change- different flowing or mating seasons
mechanical change- change in genitalia
behavioural change- courtship rituals not attractive
sympatric speciation
no geographical isolation, random mutations occur
