- Speciation is when a new species forms from an existing species
- This is due to reproductive isolation which can be allopatric or sympatric
- Allopatric speciation occurs due to geographical isolation
- Eg a population of the species gets trapped in an isolated area with a different climate
- Over time, the population will adapt to the new climate leading to changes in allele frequency and therefore changes in phenotype
- This results in individuals from the two populations being unable to breed to form fertile offspring, which means that they are different species.
- Sympatric speciation is similar to allopatric speciation but doesn’t require geographical isolation
- This can be due to:
- polyploidy (different chromosome numbers)
- seasonal isolation (different individuals have different flowering or mating seasons)
- mechanical isolation ( prevent mating)
- behavioral isolation (incorrect or different courtship rituals prevent mating)
- This can be due to:
- Genetic drift is when a change in allele frequency occurs by chance
- This can lead to evolution but often has a greater effect in smaller populations
- The diversity of life on earth today results from millions of years of evolutionary change