One of the challenges in understanding the ecological basis for species range distributions is knowing the relative importance of abiotic factors like temperature, precipitation, topography, or soil conditions (i.e., bioclimatic or potential niche) vs. biotic interactions among species like predation, competition or mutualisms (biotic or realized niche) in determining where species are located geographically. Moreover, if climate change stands to alter species geographic locations, we still don't know if their biotic interdependencies, determined by their interactions, will become unraveled—called community disassembly—or if communities will move as intact units. Modern analyses of species geographic range distributions focus on bioclimatic niches, with limited effort to consider biotic interactions. The goal of work in the Schmitz lab is to infuse greater consideration of biotic mechanisms—resolved with localized experimental research conducted in the field—into geographic scale modeling of species range distributions.
Enhancing species distribution modeling with lynx-showshoe hare interactions Researchers: Anne,Os, Jake Ivan and Tanya Shenk
Photo by Tom & Pat Leeson
Niche theory is a well-established concept integrating a diverse array of biophysical variables and multispecies interactions used to describe species geographic distribution. It is now customary to use species distribution models (SDMs) that use biophysical variables in conjunction with species location information to map their geographic ranges, the challenge remains to account for the biotic interactions of species with other community members on which they depend. Our aim was to illuminate the connection between species spatial distribution and their dependence with other species by modeling spatially explicit predator-prey interactions, which we call a trophic interaction distribution model (TIDM).
To develop the principles, we capitalized on data from a Canada lynx (Lynx canadensis) reintroduction in Colorado. Spatial location information of lynx obtained using telemetry in conjunction with coarse resolution biophysical data were used to construct a SDM. The spatial locations of lynx-snowshoe hare encounters obtained from ground-tracking in conjunction with coarse resolution biophysical data were used to construct a TIDM. The biophysical conditions associated with lynx and lynx-hare locations identified through both SDM and TIDM revealed an initial transient phase in habitat use that settled into a steady state. Nevertheless, despite the potential for the SDM to broadly encompass all lynx hunting and non-hunting spatial locations, the spatial extents of the SDM and TIDM greatly diverged; about 40% of important lynx-snowshoe hare locations identified in the TIDM were not identified in the lynx-only SDM. Our results encourage greater effort to quantify spatial locations of trophic interactions among species in a community and the associated biophysical conditions when attempting to construct models aimed at projecting current and future species geographic distributions.
Arboreal monkey movement behavior on canopy highways Researcher: Kevin
Kevin's dissertation is focused on how animals move through the canopy of the rainforest and the ecological impacts of their movements. Arboreal (tree-dwelling) mammals make up a large proportion of the mammalian biomass in tropical forests throughout Latin America and many species play critical roles in forest regeneration by distributing seeds across the landscape away from parent trees. The repeated use of specific pathways (sometimes called "canopy highways") has been observed in primates and other mammals, but quantitative characterization of these pathways has been minimal. Using remotely sensed forest structure data (LiDAR) and movement data from telemetry studies on Barro Colorado Island in Panama, I am modeling movement behavior of three arboreal monkey species in order to determine what kinds of structural features are most important for their movements. I am also monitoring animal movements in the field using motion-sensitive cameras in the canopy.
Modeling cougar habitat in the Northeast Researcher: Henry
Photo by ucumari.
Could cougars survive in the Northeastern U.S.? For his Master's project, Henry used a geographic information system to find out. Six spatially-explicit models were developed to identify top-ranking habitat in contiguous tracts large enough to support this wide-ranging species. Five models replicated methods employed in other parts of the East and Midwest, while one was original. Allowing for local-level connectivity between adjacent parcels, all six of the models identified enough habitat to support a breeding cougar population. The most conservative model identified more than 3,000 km2 of viable habitat, while the most liberal model identified more than 160,000 km2 of viable habitat. In light of the growing cougar presence in the Midwest, and the active movement of Western cougars towards the East, this research provides unique perspective on what the future range of this species might be. If these animals reach the Northeast any time soon, there is plenty of space for them to call home.