Theoretical and Empirical Approaches to the Study of Gene Flow in

Fragmented, Managed, and Continuous Populations

January 5-9, 1998

National Center for Ecological Analysis and Synthesis

University of California-Santa Barbara

Organizer: Victoria L. Sork

Participants: W. Thomas Adams, Diane Campbell, Frank Davis, Rodney Dyer, Juan Fernandez, Michael Gilpin, James Hamrick, John Nason, Joseph Neigel, Remy Petit, Outi Savolainen, Peter Smouse, Ellie Steinberg

Abstract. A workshop was held at the National Center for Ecological Analysis and Synthesis to discuss gene flow on an ecological, rather than an evolutionary, time scale. Recently, ecologists, conservation biologists, and ecosystem managers have been interested in monitoring on-going gene flow to understand environmental and landscape influences on genetic variation in existing populations. Our first goal was to review current approaches to the estimation of gene flow and their usefulness for measuring on-going gene flow. Our overwhelming conclusion was that indirect methods based on F-statistics are not sufficiently sensitive to measure gene flow on this scale. Instead, direct methods of genealogical analysis offer a reliable alternative at a small scale but may have more limited utility for scaling up. Because gene flow occurs on a landscape scale, we explored the usefulness of current population genetic approaches for scaling up our estimates and we discussed the potential contribution of metapopulation and landscape models. We evaluated the relationships between population genetic and metapopulation models, but concluded a new synthesis integrating the two approaches is not yet ready for development. To synthesize population genetic models, metapopulation models, and landscapeecology models, all three need a similar parameter of migration. So far, that is not the case. However, workshop participants explored in detail what are the requisites of scaling up the study of gene flow to the landscape level. Two models that emerged from the first meeting involve scaling up. An introduction to those models are summarized report by John Nason and Peter Smouse in a full report available on the webpage. Each of these models was pursued during to separate follow-up meetings.

Outcome of workshop:

1. Detailed web-page manuscript: "Analysis of Theoretical and Empirical Approaches to Study of Gene flow inFragmented, Managed, and Continuous Populations.

2. Symposium proposal to the International Botanical Congress

Title: : "Landscape dynamics of gene flow and plant genetic structure"

Organizers: V. Sork and R. Petit.


Pierre-Henri Gouyon, University of Paris XI-Orsay, France

James Hamrick, University of Georgia, USA

John Nason, University of Iowa, USA

Remy Petit, INRA-Bordeaux, France

Victoria L. Sork, University of Missouri-St. Louis, USA

Peter Smouse, Rutgers University, USA

Monika Wulf, Institute for Landscape ecology, Muencheberg, Germany

(authors: Monika Wulf, Andreas Ulrich, and Birgit Ziegenhagen)

3. Invitation to write TREE article


Gene Flow 2: (First follow-up Meeting: 9-12 March 1998, NCEAS)

Participants: V. Sork, J. Nason, Diane Campbell


1)Discuss and test applications of Nason gene flow model to include larger scale and interspecific gene flow.


1. Draft of manuscript for TREE

2) Write first draft of manuscript for TREE

Title: Landscape approaches to the study of on-going gene flow in plants

Authors: V. Sork, J. Nason, D. Campbell, and J. Fernandez

2. Nason tested and further developed parentage model for a larger geographical scale.


Gene Flow 3: (Second Follow-up Meeting: 22-27 April 1998, NCEAS)

Participants: V. Sork, P. Smouse, Rodney Dyer, Wendy Gram, Robert Westfall

Goals: Critically evaluate and test Smouse two-generation model.

Outcome: (Manuscripts in Progress)

1. Title: Two generation analysis of mating patterns: I. Tests of genetic heterogeneity using spatial information

Authors: Peter Smouse et al.

2. Title: Two generation analysis of mating patterns: II. Sensitivity to genetic structure and relation to pollen distance distributions

Authors: Rodney Dyer et al.

3. Title: Two generation analysis of mating patternss: III. Influence of environmental and spatial variables on genetic heterogeneity and gene flow.

Authors: V. Sork et al.