In essence, Darwin’s theory of speciation asserts that useful traits are more likely to persist in a population as they increase the competitive edge for organisms that have them. Due to the diversity of environments in which organisms may need to adapt, there would inherently be a diversity of adaptations.
Work Step by Step
Darwin described an every day competitive struggle for survival between species and between members of the same species. Creatures that were able to better compete would be more likely to survive, and more likely to sire more creatures with their same capabilities. His most famous description of this involves variation in island finches, whose phenotypes match the necessary tools for the food sources available to each different species in each different area. Though there were many different species on each island, each population was comprised of similar individuals. Your essay should include examples like this, and outline how different species (or populations therein) come to be different, as well as why members of the same population will be similar to one another.