Data from: Marine latitudinal diversity gradients, niche conservatism, and out of the tropics and Arctic: climatic sensitivity of small organisms

1. Present-day shallow marine ostracod data We constructed a comprehensive, equator-to-pole compilation of ostracod censuses from the western North Atlantic and the Arctic Oceans. We standardized ostracod taxonomy and integrated census data from previously published studies, which involved restudy of previous collections. We obtained complete ostracod census data from the original faunal slides from the US Geological Survey’s collections, including those of Hazel (1970), Valentine (1971), Cronin (1983), Cronin (1990) and Lyon (1990). Taxonomy was based on Cronin (1990) with additional information for high latitude species from Yasuhara et al. (2012) and Gemery et al. (2015). In addition to the census data from the USGS collections, census data from Kontrovitz (1976), Teeter (1975), and the Arctic Ostracode Database (Gemery et al., 2015) were added to our dataset after standardizing taxonomy using SEM pictures and descriptions from the literature. Locality information (longitude, latitude and water depth) was obtained from the original cruise reports and literature. 2. Environmental parameters Environmental parameters were obtained from various databases (Appendix 2 and Table S3). Mean annual values (1955 – 2012) for temperature (°C), dissolved oxygen (ml/L) , and salinity were obtained from the World Ocean Atlas (Baranova, 2015). pH data were obtained from the Global Ocean Data Analysis Project Bottle Data (version 2) (Olsen et al., 2016). Mean sea surface net primary productivity (NPP, in mgC/m2/day) data (1998-2014) were obtained from Oregon State University Ocean Productivity Centre (http://www.science.oregonstate.edu/ocean.productivity/) (Behrenfeld and Falkowski, 1997). Sea bottom environmental parameters were interpolated for each standard depth [based on World Ocean Atlas (Baranova, 2015)] using the Triangulated Irregular Network (TIN) interpolation from the plugin “interpolation” of QGIS (QGIS Development Team, 2016) with geographic range: latitude = 0 – 90°N; longitude = 100°W – 30°E. Interpolated environmental raster layers were overlaid with ostracod sites in QGIS (QGIS Development Team, 2016) and Point Sampling Tool was used to extract the values of environmental parameters at each site.