Global Gradients in Vertebrate Diversity Predicted by Historical Area-Productivity Dynamics and Contemporary Environment

Walter Jetz,Paul V A Fine,Georgina M Mace

doi:10.1371/journal.pbio.1001292

Walter Jetz, Paul V A Fine + Show 1 more

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https://doi.org/10.1371/journal.pbio.1001292

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Abstract

Author SummaryUnderstanding what determines the distribution of biodiversity across the planet remains one of the critical challenges in biology and has gained particular urgency in the face of environmental change and accelerating species extinctions. Our study develops a novel analytical framework to jointly evaluate historical and contemporary environmental predictors of the latitudinal gradient in the diversity of terrestrial vertebrates. The number of vertebrate species is greater in warm, productive biomes, such as tropical forests, that have both a large size and a long evolutionary history. Using just a few key predictor variables—time, area, productivity, and temperature—we are now able to explain more than 80% of the variability in biodiversity among bioregions. By integrating each of these factors at both the regional and local scale in a hierarchical model, we are able to provide a consensus explanation for broad-scale diversity gradients that encompasses both ecological and evolutionary mechanisms.

Highlights

The uneven distribution of species diversity is a key feature of life on Earth and has myriad implications
Attempts to integrate them at the appropriate scale have been limited, and we know of no study that has quantified the effect of productivity on richness gradients jointly at regional and local scales and both in terms of evolutionary and ecological processes
Linking estimates of the extents of bioregions over time allows the calculation of ‘‘time-integrated area’’ (TimeArea) [42], a synthetic index of area available to the bioregion’s biota over time, varying from just 486104 km2 integrated over 55 million years in the case of the Mediterranean bioregion at the southern tip of Africa to over 100,0006104 km2 in Eurasian temperate and African moist tropical forests

Summary

Introduction

The uneven distribution of species diversity is a key feature of life on Earth and has myriad implications. Over the past three decades, increased data availability has facilitated analyses of contiguous geographic patterns in species richness at relatively fine spatial grains (100–200 km) at both continental [7,8,9] and global scales [10,11]. At these spatial resolutions, environmental variables such as productivity or temperature have been shown to offer extremely strong statistical predictions of species richness [8,11,12,13,14,15,16,17,18]. Attempts to integrate them at the appropriate scale have been limited, and we know of no study that has quantified the effect of productivity on richness gradients jointly at regional and local scales and both in terms of evolutionary and ecological processes

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