How likely is speciation in neutral ecology ?

TL;DR

This paper investigates the likelihood of speciation within neutral ecology models by incorporating spatially-explicit population genetics, revealing limitations in species diversity achievable under neutral processes alone.

Contribution

It introduces a spatially-explicit neutral model with gene flow and speciation mechanisms, highlighting the constraints of neutral processes on biodiversity.

Findings

Neutral models with realistic mutation rates support few species.

Adding natural selection increases species number but still falls short of observed diversity.

Neutral processes alone are insufficient to explain high biodiversity levels.

Abstract

Patterns of biodiversity predicted by the neutral theory rely on a simple phenomenological model of speciation. To further investigate the effect of speciation on neutral biodiversity, we analyze a spatially-explicit neutral model based on population genetics. We define the metacommunity as a system of populations exchanging migrants and we use this framework to introduce speciation with little or no gene flow (allopatric and parapatric speciation). We find that with realistic mutation rates, our metacommunity model driven by neutral processes cannot support more than a few species. Adding natural selection in the population genetics of speciation increases the number of species in the metacommunity but the level of diversity found in Barro Colorado Island is difficult to reach.