Hotspots in the marine realm: The where and why of shark and ray biodiversity

Understanding the spatial distribution patterns of species is critical for determining the mechanisms behind marine biodiversity and appropriating conservation efforts. I used the distribution maps of all known marine species in the class Chondrichthyes to explore the degree of spatial congruency across three measures of species richness hotspot, as well as their threatened counterparts. Overall, spatial congruency was low, suggesting that conservation attention should not focus solely on areas of high species richness. I then investigated the abiotic and biotic drivers of global species richness. Sea surface temperature, productivity, and oceanic upwellings were some of the strongest abiotic predictors for richness. Areas of high richness also comprised many small ranging, younger species, indicative of species diversification occurring in the tropics. This work predominantly highlights the importance of considering which measure of richness we use when approaching conservation and advances our understanding of the biogeography of sharks and rays in the marine realm.