Spatially congruent sites of importance for global shark and ray biodiversity

identifying areas that are not true hotspots and directing valuable and limited conservation resources to those untrue hotspot areas [61]. Omission errors risk missing true hotspot areas of richness and therefore true areas of congruency between the different species richness met- rics. Omission errors can also result in a reduction of spatial options available when it comes to systematic conservation planning [62]. Aqua-maps can be used as an alternative or comple- mentary data source to the IUCN distribution maps, they are created using habitat suitability models based on point distribution data and thus give an indication of probabilities of species occurrence across the distribution ranges [63]. However, these models are rarely vetted by tax- onomists that understand the biology and geographical distribution and veracity of point rec- ords. Although the IUCN distributional data are not without limitations, they are currently the most comprehensive datasets for studying shark and ray biodiversity patterns in the ocean. While we recognize there have been range contractions, our approach is to identify the historic pattern of richness for each species and demonstrate a baseline understanding of global shark and ray biodiversity [64,65]. These maps are continually refined with routine updates of global species catalogues and field guides, lending scope to conduct more refined global analyses in future studies [66–69]. Although this was in essence a global analysis, the low richness and wide ranging nature of

species inevitably means no hotspots were found in the pelagic ecosystem. Furthermore, endemic species richness tends to be strictly coastal, unless defined differently than the one used in this study. Therefore, future work can examine the identification of hotspot areas of species richness measures and their corresponding areas of spatial congruency when coastal and pelagic ecosystems are analyzed independently. A lack of spatial congruency among the three species richness measures also opens up future work to explore the potential differences in environmental and evolutionary drivers of individual species richness measures, at varying spatial extents. For example, at smaller extents (e.g. local) species have been known to be influ- enced by local attributes like competition, and habitat availability, whereas at large extents (e.g. global) it is hypothesized that environmental variables have a stronger relationship with global species patterns [8,70,71]. In conclusion, the lack of spatial congruency between different spe- cies richness measures (and likely other biodiversity measures) could provide a global infor- mative perspective on areas that merit further attention where management could focus their efforts for the conservation of shark and ray biodiversity, especially in preparation for the 2030 Kunming Targets. The low level of spatial congruency means that the eight places with spatial overlap in all three measures of species richness might provide a useful starting point to direct

conservation planning, Marine Protected Area designation, and improved fisheries manage- ment and secure a future for sharks and rays. Supporting information S1 Fig. Global biodiversity patterns for three measures of species richness at 4˚ resolution. General richness for (a) total species, (b) evolutionarily distinct (ED) species, and (c) endemic species. (d-f) Threatened subsets of richness patterns for (d) total species, (e) evolutionarily distinct (ED) species, and (f) endemic species. Geographic coordinate system is in NAD83, projected coordinate system is lambert equal area. The data used for this figure under CC BY license is granted permission from the International Union for the Conservation of Nature (IUCN), original copyright 2011. (DOCX) S2 Fig. Global biodiversity patterns for three measures of species richness at 8˚ resolution. General richness for (a) total species, (b) evolutionarily distinct (ED) species, and (c) endemic species. (d-f) Threatened subsets of richness patterns for (d) total species, (e) evolutionarily PLOS ONE Spatially congruent sites of importance for global shark and ray biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0235559 July 6, 2020 13 / 19