Macroecology: Going from patterns to processes, a theory and its test

Abstract

This dissertation focuses on two patterns in macroecology. The first describes the distribution of abundances between species (SAD) within a single community. The second describes the structure of abundance across a species range (SAASR). The central result is that the SAASR, combined with some other assumptions, can be shown both theoretically and empirically to explain the SAD (as well as several other patterns such as the species area relationship or SPAR). Given the increased importance of the SAASR pattern, I then provide an extensive analysis of empirical data to test for the existence and exact nature of the SAASR as well as developing the first quantitative assessments of proposed mechanisms underlying the SAASR. I also clarify a current point of confusion about SADs: whether they are truly log left-skewed. I next present a philosophy of science paper on how best to test macroecological theories. Finally, I apply this approach to a well-known macroecological theory that is generally considered to be strongly tested and show that the existing tests are, in fact, weak.