Extended Data Fig. 6: Environmental patterns.

a–d, Mean annual environmental data for each latitudinal (1.0°) and bathymetric (100 m) cell across our study area for comparison with phylodiversity analyses. A lens of relatively hot (a) salty (b) water occurs at shallow depths across tropical and temperate latitudes (0–40° S). Antarctic intermediate water sinks at sub-Antarctic latitudes and flows north to subtropical latitudes (20° S) at mid-bathyal depths (around 1,000 m). c, Deoxygenated ‘deep’ water flows southwards from the northern hemisphere at lower bathyal depths, shoaling off the Antarctic continent. Cold, dense, oxygen-rich ‘bottom’ water sinks near Antarctica, flowing northwards at abyssal depths. d, Yearly net primary production peaks at temperate latitudes over the study area, driving elevated carbon flux to the seafloor; Antarctic production is highly seasonal. e, Area of depth strata per degree of latitude across the study region, calculated by counting the number of cells of each category for each degree of latitude in the ETOPO1⁶² raster GIS layer (0.01° resolution) and adjusting for the reducing circumference of the Earth with increased latitude. There is limited terrestrial, sublittoral and upper bathyal habitat in the Southern Ocean between the Australian/New Zealand continental masses and Antarctica.