Journal of Heredity Advance Access published online on November 2, 2007
Journal of Heredity, doi:10.1093/jhered/esm089
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Extensive Long-Distance Pollen Dispersal in a Fragmented Landscape Maintains Genetic Diversity in White Spruce
From the Canada Research Chair in Forest and Conservation Genomics and Biotechnology, Faculty of Forestry and Environmental Management, University of New Brunswick, PO Box 44555, 28 Dineen Drive, Fredericton, NB E3B 6C2, Canada (O'Connell and Rajora); and the Canadian Forest Service—Atlantic Forestry Centre, Natural Resources Canada, PO Box 4000, Fredericton, NB E3B 5P7, Canada (Mosseler)
Address correspondence to O. P. Rajora at the above address or e-mail: Om.Rajora{at}unb.ca.
Conifers are among the most genetically diverse plants but show the lowest levels of genetic differentiation, even among geographically distant populations. High gene flow among populations may be one of the most important factors in maintaining these genetic patterns. Here, we provide empirical evidence for extensive pollen-mediated gene dispersal between natural stands of a widespread northern temperate/boreal conifer, Picea glauca. We used 6 polymorphic allozyme loci to quantify the proportion of seeds sired by pollen originating from different sources in a landscape fragmented by agriculture in North Central Ontario, Canada. In 7 stands, a small proportion of seeds were sired by self-pollen or neighboring trees but 87.1% (±1.7% standard error [SE]) of seeds were sired by pollen from at least 250 to 3000 m away. In 4 single isolated trees, self-fertilization rates were low and more than 96% (±1.3% SE) of seeds were sired by immigrant pollen. The average minimum pollen dispersal distance in outcrossed matings was 619 m. These results provide strong evidence that extensive long-distance pollen dispersal plays a primary role in maintaining low genetic differentiation among natural populations of P. glauca and helps maintain genetic diversity and minimize inbreeding in small stands in a fragmented landscape.
Corresponding Editor: James Hamrick
Received December 3, 2006
Accepted September 26, 2007