HOME     SCHEDULE     AUTHOR INDEX     SUBJECT INDEX              

PARENT SESSION

Investigating landscape connectivity using genetic isolation by distance and least-cost modeling in the American marten.

Broquet, Thomas*,1, Ray, Nicolas2, Petit, Eric1, Fryxell, John3, Burel, Françoise1, 1 University of Rennes 1, Rennes, France2 University of Melbourne, Melbourne, Australia3 University of Guelph, Guelph, Ontario, Canada

ABSTRACT- Empirical studies of landscape connectivity, as defined by the interaction between the structure of a landscape and the movement of individuals, are often limited by the difficulty of directly measuring animal movement. "Indirect" approaches of dispersal involving genetic analyses therefore seem to provide a complementary tool to the "direct" methods. Here the effect of landscape on dispersal was investigated in a forest associated species, the American marten (Martes americana) using the genetic model of isolation by distance (IBD). This model assuming isotropic dispersal in a homogeneous environment is characterized by decreasing genetic differentiation among individuals separated by increasing geographic distances. The effect of landscape features on this genetic pattern was therefore used to test for a departure from spatially homogeneous dispersal. This study was conducted on two marten populations in homogeneous vs. heterogeneous habitat in a harvested boreal forest in Ontario (Canada). A pattern of IBD was evidenced in the homogenous landscape whereas no such pattern was found in the near-by harvested forest. To test whether the structure of the landscape may be accountable for this difference, we used effective distances taken into account the effect of landscape features on marten movement instead of Euclidean distances in the model of isolation by distance. Effective distances computed using least-cost modeling were better correlated to genetic distances in both landscapes, thereby showing that the interaction between landscape features and dispersal in Martes americana may be detected through individual-based analyses of spatial genetic structure. However the simplifying assumptions of genetic models and the extremely low proportions of variance in genetic differentiation explained by these models seem to limit their utility in quantifying the effect of landscape structure on dispersal (landscape connectivity as a dependent variable).

Key words: Isolation by distance, Dispersal, Landscape connectivity, Effective distances

All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.