Beginning of Essay
In science, macro at the beginning of a word just means "big", and micro at the beginning of a word just means "small" (both from the Greek words). In evolutionary biology today, macroevolution is used to refer to any evolutionary change at or above the level of ....

Middle of Essay
.... of macroevolution. Punctuated equilibrium theory proposes that once species have originated, and adapted to the new ecological niches in which they find themselves, they tend to stay pretty much as they are for the rest of their existence. Phyletic gradualism suggests that species continue to adapt to new challenges over the course of their history. Species selection and species sorting theories claim that there are macroevolutionary processes going on that make it more or less likely that certain species will exist for very long before becoming extinct, in a kind of parallel to what happens to genes in microevolution. The history of the conc ....