Population is in same geographical area
Become reproductively isolated because of the 3 changes
No geneflow between populations
Conditions change on either side
Different selection pressures
Determine whether allele is advantageous
Individuals with advantageous allele - better adapted
More likely to survive + reproduce
Pass on advantageous allele to offspring
Overtime, frequency of advantageous allele increases
Different allele frequency in populations
2 genetically distinct populations that cant interbreed to produce fertile offspring
So 2 different species
