Journal

Conservation Biology

Abstract

Habitat loss and fragmentation have independent impacts on biodiversity; thus, field studies are needed to distinguish their impacts. Moreover, species with different locomotion rates respond differently to fragmentation, complicating direct comparisons of the effects of habitat loss and fragmentation across differing taxa and landscapes. To overcome these challenges, we combined mechanistic mathematical modeling and laboratory experiments to compare how species with different locomotion rates were affected by low (~80% intact) and high (~30% intact) levels of habitat loss. In our laboratory experiment, we used Caenorhabditis elegans strains with different locomotion rates and subjected them to the different levels of habitat loss and fragmentation by placing Escherichia coli (C. elegans food) over different proportions of the Petri dish. We developed a partial differential equation model that incorporated spatial and biological phenomena to predict the impacts of habitat arrangement on populations. Only species with low rates of locomotion declined significantly in abundance as fragmentation increased in areas with low (p = 0.0270) and high (p = 0.0243) levels of habitat loss. Despite that species with high locomotion rates changed little in abundance regardless of the spatial arrangement of resources, they had the lowest abundance and growth rates in all environments because the negative effect of fragmentation created a mismatch between the population distribution and the resource distribution. Our findings shed new light on incorporating the role of locomotion in determining the effects of habitat fragmentation.

Overview

This paper grew out of a fairly simple ecological question: when habitat is broken up, do fast- and slow-moving species respond in the same way? The answer turns out to be no, and one of the main goals of the paper was to make that difference precise using both experiments and a mathematical model.

The experimental side uses C. elegans strains with different locomotion rates, while the modelling side uses a PDE framework to track how movement, reproduction, and habitat arrangement interact. What comes out is a pretty clear principle: slower movers are much more vulnerable to fragmentation, while faster movers can tolerate it better, although that does not automatically mean they do well overall.

More broadly, the paper is about separating the effects of habitat loss from the effects of fragmentation, and showing that movement behaviour is a big part of that story. In that sense, it is less about one specific species and more about a general principle for how movement rate shapes a population’s response to patchy environments.

Keywords

habitat fragmentation; habitat loss; locomotion rate; experiment; partial differential equations; theory

Links

• DOI / Journal page