Data from: Phylogenetic measures reveal eco-evolutionary drivers of biodiversity along a depth gradient

Energy and environmental stability are positively correlated with species
richness along broad-scale spatial gradients in terrestrial ecosystems, so
their relative importance in generating and preserving diversity cannot be
readily disentangled. This study seeks to exploit the negative correlation
between energy and stability along the oceanic depth gradient to better
understand their relative contribution in shaping broadscale biodiversity
patterns. We develop a conceptual framework by simulating speciation and
extinction along energy and stability gradients to generate expected
patterns of biodiversity for a suite of complementary phylogenetic
diversity metrics. Using a time-calibrated molecular phylogeny for New
Zealand marine ray-finned fishes and a replicated community ecological
sampling design, we then modelled these metrics along large-scale depth
and latitude gradients. Our results indicate that energy-rich shallow
waters may be an engine of diversity for percomorphs, but also suggest
that recent speciation occurs in ancient fish lineages in the deep sea,
hence questioning the role of energy as a key driver of speciation.
Despite potentially facing high extinction early in their evolution,
ancient phylogenetic lineages specialized for the deep-sea were likely
preserved by environmental stability during the Cenozoic. Furthermore,
intermediate depths might be a “museum” (or zone of overlap) for distinct
lineages that occur predominantly in either shallow or deep-sea waters.
These intermediate depths (500-900m) may form a “phylogenetic diversity
bank”, perhaps providing a refuge during ancient (Mesozoic) extreme anoxic
events affecting the deep sea and more recent (Pliocene-Pleistocene)
climatic events occurring in shallow ecosystems. Finally, the phylogenetic
structures observed in fish communities at intermediate depths suggest
other processes might restrict the co-occurrence of closely related
species. Overall, by combining a conceptual framework with models of
empirical phylogenetic diversity patterns, our study paves the way for
understanding the determinants of biodiversity across the largest habitat
on earth.