Speciation

Question 1

reproductive speciation

Answer 1

evolution of a new species from an existing one
changes in alleles + phenotypes of some individuals in a population prevent them from successfully breeding
changes- season changes, mechanical changes, behavioural changes (courtship)

Question 2

allopatric

Answer 2

isolation of two populations
variation is already present 
different selection pressures/ environmental conditions
selection of different features
allele frequencies change
no gene flow, separate gene pools
cant interbreed

Question 3

sympatric

Answer 3

occurs in same place due to seasonal, mechanical or behavioural changes
mutation causes change
no gene flow
gene pools separate
allele frequencies change
can no longer interbreed to produce fertile offspring
(disruptive selection as both still survive)

Question 4

genetic drift

Answer 4

changes in gene pool due to chance
where some alleles are lost or favoured by chance
normally effects small populations as in large populations even out allele frequencies are evened out

Question 5

bottleneck effect

Answer 5

extreme example of genetic drift where the size of the population is severely reduced eg by a natural disaster

Question 6

founder effect

Answer 6

when a small group of organisms splits off from the main group of organisms to form a colony
colony may not represent the genetic diversity of the original population
similar to bottleneck but occurs via a different mechanism (colonisation)