“A general, synthetic model for predicting biodiversity gradients from environmental geometry”

Posted on

Kevin Gross and Andrew Snyder-Beattie

Environmental geometry can drive nuanced and realistic latitudinal and elevational biodiversity gradients

The geometry of the global environment may explain surprisingly nuanced biodiversity patterns

A sphere with a global environment that varies from one extreme (yellow) at its Equator to an opposite extreme (blue) at its poles, and the ranges of three hypothetical species (shown by the solid magenta outlines). When many more species ranges are added, those ranges pile up unevenly, resulting in latitudinal biodiversity gradients that mirror those found in nature.
(Credit: Kevin Gross)

Why are there so many species in the tropics, and so few at the poles? Ecologists have debated explanations for global biodiversity patterns for over a century. Now, researchers from North Carolina State University and the Oxford Martin School at the University of Oxford have produced a new study in The American Naturalist suggesting that the mere position of different habitats could influence the number of species found in each. The investigators considered the elementary shapes of a sphere and cone, modelled how different locations on those shapes lend themselves to acquiring more or fewer species, and compared their predictions to real biodiversity patterns across latitudinal or elevational gradients.

Despite its simplicity, this “environmental geometry” model predicts biodiversity gradients that are both complex yet seemingly realistic. On a sphere, the model predicts roughly constant biodiversity in the tropics, a steep drop in biodiversity through the middle latitudes, and a biodiversity plateau near the poles. On a cone, the model predicts that biodiversity will be greatest at low‐to‐mid elevations. Kevin Gross, one of the authors of the study says, “While we’ve known for many years that basic geometry may help explain global biodiversity patterns, the surprise here is how an uncomplicated model produces nuanced predictions that appear consistent with data for many species groups. Intriguingly, it follows that the details in biodiversity patterns may be more than just random noise, and may instead offer important clues to why these patterns arise.”

Although research doesn’t yet test statistically the extent to which environmental geometry shapes global biodiversity, the researchers hope future studies will investigate this. Andrew Snyder-Beattie, a co‐author of the study, goes on to say “if these geometry models are capturing a real underlying mechanism, it could have implications for a number of emerging ecological issues such as the impacts of climate change, habitat fragmentation, or species invasions.” Read the Article