ABSTRACT
Georges-Louis Leclere, Comte de Buffon, is given credit for developing the ‘rst principle of biogeography (also known as Buffon’s law). He observed that different plants and animals occurred in different geographical regions even though the climates in those regions were the same. The principle of evolution, which lineages change in time and space, is attributed to Charles Darwin and Alfred Russell Wallace. With just these two principles, it was possible to form the Science of Biogeography, and we are still trying to ‘gure it all out. This chapter will discuss probable causes for the present worldwide distribution and diversity of freshwater ‘shes. Subsequent chapters will evaluate factors associated with the distribution and abundance of freshwater and marine ‘shes in speci‘c systems and habitats.
