Good Example Of Essay On Speciation: Apple Maggot And Hawthorn Maggot.

1. Apple Maggots are pests that infest apples. The insect breeds and lays its egg on the fruit. The maggots that hatch from these egg feed on the fruit and drop to the soil, where they pupate. Adult insects fly to the apple tree once again, to breed and lay eggs on the fruit. Hawthorn maggot is a species that diverged from apple maggots. They show a preference for Hawthorn fruit, over apple. The speciation of Hawthorn maggot from Apple maggot, is an example of sympatric speciation. Sympatric speciation occurs due to reproductive isolation.
2. Though Hawthorn and Apple maggot, are physically indistinguishable, scientists have observed certain genetic differences in both species. There is no geographical difference. However, Apple maggots and Hawthorn maggots, strongly prefer to mate within their own species and are specific to the fruit they choose to lay eggs.
3. Prior to the introduction of Hawthorn, Apple maggot were the only species that existed and infested apples. However, following the introduction of Hawthorn in North America in 1864, Apple maggots began to infest Haworth. The Apple maggots that preferred Haworth over Apples, slowly evolved into a distinct species. Haworth and Apples have a slightly different ripening time. However, death from attack by the parasitoid wasps were high in Hawthorn maggots when compared to Apple maggot.
4. The initial genetic polymorphism that existed between Apple and Haworth maggot must have resulted in their different choices and behaviors. The different choices must have led to reproductive isolation within the species, which in the course of time gave rise to a new species.
5. More information about reproductive behavior will help confirm the confidence in sympatric speciation.