Evidence for large-scale effects of competition: niche displacement in Canada lynx and bobcat

Abstract

Determining the patterns, causes and consequences of character displacement is central to our understanding of competition in ecological communities. However, the majority of competition research has occurred over small spatial extents or focused on fine-scale differences in morphology or behaviour. The effects of competition on broad-scale distribution and niche characteristics of species remain poorly understood but critically important. Using rangewide species distribution models, we evaluated whether Canada lynx (Lynx canadensis) or bobcat (Lynx rufus) were displaced in regions of sympatry. Consistent with our prediction, we found that lynx niches were less similar to those of bobcat in areas of sympatry versus allopatry, with a stronger reliance on snow cover driving lynx niche divergence in the sympatric zone. By contrast, bobcat increased niche breadth in zones of sympatry, and bobcat niches were equally similar to those of lynx in zones of sympatry and allopatry. These findings suggest that competitively disadvantaged species avoid competition at large scales by restricting their niche to highly suitable conditions, while superior competitors expand the diversity of environments used. Our results indicate that competition can manifest within climatic niche space across species' ranges, highlighting the importance of biotic interactions occurring at large spatial scales on niche dynamics.

Isolation of peripheral populations of Canada lynx (Lynx canadensis)

“…Climate change is also expected to cause a northward shift in bobcat (Lynx rufus (Schreber, 1777)) distribution (Anderson and Lovallo 2003;Roberts and Crimmins 2010), increasing the area of sympatry of lynx and bobcat. This interspecies range overlap will threaten lynx population persistence at the southern extent of their range through competition (Peers et al 2013) and hybridization (Schwartz et al 2004;Homyack et al 2008;Koen et al 2014b). If the St. Lawrence River impedes bobcat gene flow as it does lynx, then it is possible that the river might protect the core of lynx range north of the St. Lawrence River by limiting northward expansion of the range of bobcats from south of the river.…”

Habitat monitoring and projections for Canada lynx: linking the Landsat archive with carnivore occurrence and prey density

“…), which may benefit lynx if competitive interactions do not limit their ability to expand into areas of new habitat (e.g. Peers, Thorton & Murray ). Loss and fragmentation of habitat in northern Maine may have important implications for lynx conservation if persistence of Maine's population, which occurs along the southern periphery of the species' geographic range, requires connectivity to boreal populations (Walpole et al .…”

The influence of coyote on Canada lynx populations assessed at two different spatial scales

“…Hence, our approach followed the principle that nuisance and confounding factors should be maximized before testing a relationship of interest (Araujo andLuoto 2007, Guillaumet et al 2008). However, this approach may underestimate the fact that the relationship with environment, such as lynx 'preference' for deep snow (Buskirk et al 2000), may itself be a consequence of competition (Peers et al 2013). In addition, our conclusions may not apply to the extreme southern end of the lynx range (e.g., in the United States), where we did not have any data, and where competitor densities may be highest.…”

“…First, developing and contrasting habitat use models in allopatry and sympatry (or contrasting in time pre-and post-coyote era, e.g. in Quebec) may permit to determine whether lynx is subject to ecological displacement, for instance into deeper snow areas, in the presence of coyote (see Peers et al 2013 for a case study of lynx and bobcat). Although the entire lynx's range may be considered, environmental values should be gathered at the site (local) scale, and not at the landscape scale as in the present study (trapline-level).…”