What ecological factors shape species-area curves in neutral models?

TL;DR

This study investigates how ecological factors like local population size and habitat saturation influence species-area relationships in neutral models, revealing that larger local populations flatten SARs and habitat saturation has minimal effect.

Contribution

The paper demonstrates that local population size significantly affects species-area curves in neutral models, offering insights into differences observed across organism sizes.

Findings

Species-area curves become shallower with increased local population size.

Habitat saturation has a marginal impact on species-area relationships.

Microorganisms exhibit flatter SARs compared to larger organisms.

Abstract

Understanding factors that shape biodiversity and species coexistence across scales is of utmost importance in ecology, both theoretically and for conservation policies. Species-area relationships (SARs), measuring how the number of observed species increases upon enlarging the sampled area, constitute a convenient tool for quantifying the spatial structure of biodiversity. While general features of species-area curves are quite universal across ecosystems, some quantitative aspects can change significantly. Several attempts have been made to link these variations to ecological forces. Within the framework of spatially explicit neutral models, here we scrutinize the effect of varying the local population size (i.e. the number of individuals per site) and the level of habitat saturation (allowing for empty sites). We conclude that species-area curves become shallower when the local population size increases, while habitat saturation, unless strongly violated, plays a marginal role. Our findings provide a plausible explanation of why SARs for microorganisms are flatter than those for larger organisms.