Identify the Main Point or Issue in the Following Passage

Essay

Identify the main point or issue in the following passage, and decide whether the rest of the passage offers reasons for the main point (such as, whether the passage contains an argument), whether it illustrates (provides examples for) the main point, whether it explains the point, is irrelevant to the point, and so on.
"In the last two hundred years, the theoretical landscape of biology has changed drastically, however. Species and other taxa are not the result of divine creation, but the products of evolution. Taxa are not static, timeless classes of organisms, but evolving and temporary entities. The theoretical assumptions of Linnaean system have been replaced by those of Darwinism and the Modern Synthesis."
-Mark Ereshefsky, "Species and the Linnaean Hierarchy," in Species, ed. by R.
A.Wilson