New data and taxonomic changes influence our understanding of biogeographic patterns: A case study in Australian skinks

Species are the most commonly used unit of biogeography research, and in many conservation schemes. For many faunal groups, taxonomy is in a constant state of flux, with new species being described, and our concept of existing species regularly being refined. Using the most diverse lineage of Australian lizards (460+ species), the skinks (Family Scincidae), we quantified the impacts of taxonomic changes over time on our understanding of species richness, endemism and beta diversity. We generated surfaces of species richness, endemism and beta diversity from four editions (1975, 1988, 2000, 2014) of an authoritative field guide to understand how taxonomic shifts, and enhanced biogeographic knowledge, influenced the inferred biogeographic patterns in Australian skinks. The number of recognized Australian skink species has increased 2.3-fold since 1975. The Wet Tropics was the major hotspot for (mostly locally endemic) species additions. Hotspots of species richness and beta diversity remained broadly similar over time, but some important local hotspots shifted. Endemism hotspots were weakly associated with hotspots of species additions over time except in the Wet Tropics. The major shifts in biogeographic patterns, which were not associated with taxonomic changes, resulted from better knowledge of species distributions through time. We hypothesize that the effects of taxonomy on biogeographic patterns we found generalize across clades and regions—especially away from major research hotspots. We suggest an understanding of the impact of taxonomic changes on conservation priorities for particular regions and taxonomic groups is needed.