18.5 isolation & speciation

Question 1

how does speciation happen through adaptive radiation?

Answer 1

• species is seperated geographically
• reproductive isolation / no gene flow / gene pools kept seperate
• exposed to different selection pressures
• variation due to mutations
• change in allelic frequency / advantageous allele selected for
• can’t interbreed to produce fertile offspring

Question 2

what are the different isolation mechanisms?

Answer 2

geographical - seperated by physical barriers
ecological - inhabit different habitats
temporal - different breeding seasons
behavioural - different courtship behaviour
mechanical - genitalis don’t interact
gametic - male gamete doesn’t fuse with female gamete
hybrid sterility - hybrid doesn’t produce viable gamete / offspring

Question 3

what is allopatric speciation?

Answer 3

species are seperated geographically -> prevent interbreeding

Question 4

what is sympathic speciation?

Answer 4

speciation within a population within the same area & don’t interbreed

Question 5

where does genetic drift occur?

Answer 5

occur in small populations w. smaller gene pool

Question 6

what will result with a great effect of genetic drift?

Answer 6

population change rapidly & more likely to develop new species

Question 7

how does genetic drift affect allelic frequency?

Answer 7

allele being passed on will cause great change due to high allelic frequency