Species' Border Working Group Report.

All species are distributed in space -- but within limits. Understanding the factors determining range limits is a central concern in both ecology (Lawton et al. 1994, e.g., the study of invasions, Lodge 1993) and evolutionary biology (e.g., faunal responses to environmental fluctuations, Graham et al. 1996). There is rapidly growing interest in the ecology and evolution of species' borders (e.g., Stevens and Fox 1991, Hoffmann and Blows 1994, Gaston 1996, Kirkpatrick and Barton, in press, Holt and Gomulkiewicz, in press). This working group will focus on theoretical studies of species' borders, the integration of models with analyses of empirical patterns, and the blending of ecological and evolutionary perspectives.

First Meeting -- 16 Oct to 21 Oct 1997

The NCEAS Species' Borders working group met for the first time in October, 1997. Group members in attendance were:

Tim Blackburn, Imperial College at Silwood Park
Ted Case, University of California, San Diego
Marie-Josee Fortin, Universite de Montreal
Steven Gaines, University of California, Santa Barbara
Richard Gomulkiewicz, Washington State University
Robert Holt, University of Kansas
Dawn Kaufman, University of New Mexico
Tadeusz Kawecki, University of Maryland
Timothy Keitt, University of California, Santa Barbara
Joel Kingsolver, University of Washington
Russell Lande, University of Oregon
Mark Lewis, University of Utah
Brian Maurer, Brigham Young University
Mark McPeek, Dartmouth College
Camille Parmesan, University of California, Santa Barbara
A. Townsend Peterson, University of Kansas
Rafe Sagarin, University of California, Santa Barbara
Mark Taper, Montana State University
Yaron Ziv, University of Arizona

During first several days of the meeting, consisted of individual presentations by the working group members.

After much discussion, we split into four sub-groups, each group charged with writing a manuscript on a particular topic. The topics included:

1) Evolutionary and ecological determinants of single species range limits (Holt, Gumulkiewicz, Lewis, Kawecki, Keitt, McPeek, Lande). This group will consider single species models with two or more populations linked via dispersal. In the simplest model, one population is a "core" source population and the other is a peripheral sink population. The goal is generalize results from simple models to ecological and evolutionary dynamics at the edge of species' distributions.

2) Dynamics of multi-species community models: predator-prey, host-parasite, and community trophic dynamics (McPeek, Case, Holt, Taper, Ziv, Fortin). This group will extend the single species results to community interactions and identify one or more example systems for analysis and discussion.

3) Methods for detecting and characterizing the geometry of species' borders (Fortin, Keitt, Blackburn, Maurer, Kaufman). This group has the goal of identifying promising methods to measure geographic variation in abundance, and in particular, identify appropriate methods for delineating range boundaries. One or more example data sets may be used to illustrate and compare different methods.

4) A synthesis of species' borders across terrestrial and marine ecosystems (Parmesan, Gains, Sagarin, Kingsolver, Kauffman). This group will consider differences between terrestrial and marine systems and how they relate to species' geographic range distributions.

The goal of the subgroups is to produce a series of manuscripts to be submitted to the "special features" section of Ecology. The special feature will set the stage for continued work culminating in a edited volume.