Taxonomic Checklists as Biodiversity Data: How Series of Checklists can Provide Information on Synonymy, Circumscription Change and Taxonomic Discovery

Taxonomic checklists are a fundamental and widely-used product of taxonomy, providing a list of recognized taxa within a taxonomic group in a particular geographical area. Series of taxonomic checklists provide snapshots of recognized taxa over a period of time. Identifying and classifying the changes between these checklists can provide information on rates of name, synonym and circumscription change and can improve aggregation of datasets reconciled to different checklists.To demonstrate this, I used a series of North American bird checklists to test hypotheses about drivers of splitting rates in North America birds. In particular, I asked if splitting was predominantly undoing previous lumping that happened during the heyday of the modern synthesis. I found that bird species have been split at an accelerating rate since the 1980s. While this was partially the result of previously lumped species being resplit, most splits were unrelated to previous lumps and thus represent new discoveries rather than simply the undoing of previous circumscription changes. I also used a series of North American freshwater algal checklists to measure stability over fifteen years, and found that 26% of species names were not shared or synonymized over this period. Rates of synonymization, lumping or splitting of species remained flat, a marked difference from North American birds. Species that were split or lumped (7% of species considered) had significantly higher abundance than other species in the USGS NAWQA dataset, a biodiversity database that uses these checklists as an index. They were associated with 19% of associated observations, showing that a small number of recircumscribed species could significantly affect interpretation of biodiversity data.To facilitate this research, I developed a software tool that could identify and annotate taxonomic changes among a series of checklists, and could use this information to aggregate biodiversity data, which will hopefully facilitate similar research in the future. My dissertation demonstrates the value of taxonomic checklists series to answer specific questions about the drivers of taxonomic change ranging from philosophical and technical changes to characteristics of species themselves such as their abundance.