Habitat fragmentation promotes spatial scale separation under resource competition

TL;DR

This paper investigates how habitat fragmentation influences species distribution, showing that competition and network structure lead to spatial segregation, which could promote speciation in fragmented landscapes.

Contribution

It introduces an analytical and numerical framework for understanding how competition and dispersal in networked habitats cause spatial separation of species based on competitive traits.

Findings

Strong competitors concentrate in central patches

Weak competitors are displaced to peripheral patches

Fragmentation enhances spatial segregation and potential speciation

Abstract

Habitat fragmentation, often driven by human activities, alters ecological landscapes by disrupting connectivity and reshaping species interactions. In such fragmented environments, habitats can be modeled as networks, where individuals disperse across interconnected patches. We consider an intraspecific competition model, where individuals compete for space while dispersing according to a nonlinear random walk, capturing the heterogeneity of the network. The interplay between asymmetric competition, dispersal dynamics, and spatial heterogeneity leads to nonuniform species distribution: individuals with stronger competitive traits accumulate in central (hub) habitat patches, while those with weaker traits are displaced toward the periphery. We provide analytical insights into this mechanism, supported by numerical simulations, demonstrating how competition and spatial structure jointly influence species segregation. In the large-network limit, this effect becomes extreme, with dominant individuals disappearing from peripheral patches and subordinate ones from central regions, establishing spatial segregation. This pattern may create favorable conditions for speciation, as physical separation can reinforce divergence within the population over time.