define species
a population of reproducing organisms that is isolated from other populations
allopatric speciation
eg: antelope squirrels- different species on grand canyon but birds there is no change
genetic drift
eg snapdragon
founder effect/ bottleneck effect
due to population suddenly crashing or moved from one place to another- loose rarer alleles
sympatric speciation
speciation that occurs in same homeland
examples of sympatric speciation
difference in uk and spanish birds- bevause of different migaratory times
what causes speciation
different distribution - can hybridise
how long does speciation take in animals
5 million years