Against the backdrop of resource competition, ecological coexistence appears mysterious: if species must specialize in order to exist, how can dozen of similar species inhabit the same environment? Many explanations have been put forward, but efforts have remained primarily theoretical, with simple models demonstrating coexistence via simple mechanisms. Therein lies the problem --- explanations are simple by design, but nature is complex. Here, we improve upon Modern Coexistence Theory, a mathematical framework that can be used to measure the relative importance of different explanations for coexistence. Innovations range from the methodological to the conceptual.

Additionally, we attempt to understand the causes of unexpected population crashes, also known as catastrophes or ecological "black swan" events. Many such crashes do not fit the common explanation of tipping points resulting from changing environmental conditions. We provide an alternative and general mechanism for population crashes in a static environment, namely stochasticity (of any variety) combined with multiple episodes of density dependence. This explanation is confirmed in experimental microcosms of the red flour beetle, and connections to real-world population crashes are discussed.

In China’s early medieval period, scholastic erudition and refined self-expression were requisite talents of the literate elite, and achievement in both areas depended on the production, circulation, and consumption of texts. This dissertation examines several methods of textual organization and compilation that arose and flourished in this period. Although such works served as testaments to the broad erudition of their compilers, they were also criticized for their unrestrained ambition, disorderly structure, and problematically “miscellaneous” contents.

The first two chapters address bibliographic treatises compiled during the Han and early Tang dynasties, showing how these ambitious scholarly projects relegated complexly organized works to categories reserved for “miscellaneous” texts. I find that the earlier treatise, contained in Han shu, is inconsistent in the qualities it assigns to texts it describes as za, or “miscellaneous,” while the later treatise, found in Sui shu, displays the influence of the centuries of intervening textual production and circulation through a new interest in scribal practices and compilation techniques, which is also apparent in its critiques of all its “miscellaneous” texts.

Each of the remaining three chapters addresses a different method of textual reuse that arose in the centuries between these two bibliographies. In chapter three, I discuss the extensive historiographic annotations to Sanguo zhi and Shishuo xinyu, which have themselves been criticized for their disorderliness, and also make frequent use of texts bibliographies describe as “miscellaneous.” Chapter four is focused on Jinlouzi, a uniquely structured compilation of private writings and gathered anecdotes, showing how its distinctive approach to textual reuse and organization has influenced its complex transmission and reception. Chapter five discusses collections of liezhuan biographies compiled for several dynastic histories, using analysis of phrases that describe reading and erudition to examine the development of a standard biographical style. By combining digital analyses of patterns within these texts with investigation of their structure and contents, I show how these texts, though maligned for their disorderliness and “miscellaneousness,” are all attempts to bring a quickly expanding corpus to order, and to find new ways to make use of the many texts to which their compilers had access.