The mathematical influence on global patterns of biodiversity

Abstract

Although we understand how species evolve, we do not appreciate how this process has filled an empty world to create current patterns of biodiversity. Here, we conduct a numerical experiment to determine why biodiversity varies spatially on our planet. We show that spatial patterns of biodiversity are mathematically constrained and arise from the interaction between the species’ ecological niches and environmental variability that propagates to the community level. Our results allow us to explain key biological observations such as (a) latitudinal biodiversity gradients (LBGs) and especially why oceanic LBGs primarily peak at midlatitudes while terrestrial LBGs generally exhibit a maximum at the equator, (b) the greater biodiversity on land even though life first evolved in the sea, (c) the greater species richness at the seabed than at the sea surface, and (d) the higher neritic (i.e., species occurring in areas with a bathymetry lower than 200 m) than oceanic (i.e., species occurring in areas with a bathymetry higher than 200 m) biodiversity. Our results suggest that a mathematical constraint originating from a fundamental ecological interaction, that is, the niche–environment interaction, fixes the number of species that can establish regionally by speciation or migration.

Truncated bimodal latitudinal diversity gradient in early Paleozoic phytoplankton

“…The model has been fully described and tested in Beaugrand et al . ( 7 , 41 , 90 ). The principle of the model is simple: It starts by creating a large number of niches on the basis of temperature (here, all possible niches between −1.8° and 44°C) ( 7 ).…”

“…Here, the model implements a set of basic ecological/climatic principles to consider the interaction between the thermal niches of species and spatiotemporal fluctuations in temperature at an annual time scale. The model has been fully described and tested in Beaugrand et al (7,41,90). The principle of the model is simple: It starts by creating a large number of niches on the basis of temperature (here, all possible niches between −1.8° and 44°C) (7).…”

Odonate Diversity Patterns in Italy Disclose Intricate Colonization Pathways

“…Species richness increases southwards following the so-called latitudinal gradient as a result of the prominent role of southern areas as Pleistocene refugial centers for European fauna. The latitudinal gradient in species richness (i.e., the decrease in biodiversity from the Equator to the poles) is one of the most notable biodiversity patterns on Earth [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. In Europe, a decrease in species richness with increasing latitude has been found in many hexapod groups, and it has been largely interpreted as a consequence of species responses to climatic gradients and historical factors [ 22 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ].…”

Biogeographical Patterns of Earwigs in Italy

“…Prediction 1a. As a result of the role of the southern regions as refugial areas during the Pleistocene glacials, earwig species richness is expected to increase southward, thus following the ‘latitudinal gradient’, one of the most prominent patterns of biodiversity [ 2 , 21 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. This is because during the Pleistocene glacials, most of central and northern Europe was covered with ice, and their current faunas are a result of post-Pleistocene range expansions from southern refugia.…”