Habitat continuity and geographic distance predict population genetic differentiation in giant kelp
| by Alberto F, Raimondi PT, Reed DC, Coelho NC, Leblois R, Whitmer A, Serrăo EA |
| Ecology 91 (2010), pp. 49-56 |
| Output type: publication |
 URL: http://dx.doi.org/10.1890/09-0050.1 |
Isolation by distance (IBD) models are widely used to
predict levels of genetic connectivity as a function of Euclidean distance, and
although recent studies have used GIS-landscape ecological approaches to
improve the predictability of spatial genetic structure, few if any have addressed
the effect of population size and habitat continuity on gene flow. Landscape effects on genetic
connectivity are even less understood in marine populations, where habitat
mapping is particularly challenging. In this study, we model spatial genetic structure of a
habitat-structuring species, the giant kelp Macrocystis pyrifera, using highly variable microsatellite markers. GIS mapping was used to characterize
habitat continuity and distance between sampling sites along the mainland coast
of the Santa Barbara Channel, and their roles as predictors of genetic
differentiation were evaluated. Connectivity (σ) and Ne were estimated by comparing our IBD slope with those
from simulations incorporating the habitat continuity. We found the highest
allelic richness yet reported for macroalgae, (7 to 50 alleles×locus-1).
The best regression model relating genetic distance to habitat variables
included both geographic distance and habitat continuity, which were
respectively, positively and negatively related to genetic distance. Our
results provide strong support for a dependence of gene flow on both distance
and habitat continuity. Our estimates of connectivity among populations were
consistent with previous estimates obtained using empirical and theoretical
approaches.
