Hoban, Sean , Schlarbaum, Scott , Brosi, Sunshine , Romero-Severson, Jeanne .
Genetic change in a regenerating patch of butternut, a threatened forest tree, is attributable to the contribution of few successful parents.
The dynamics of genetic change during in-situ recovery of rare or threatened plant species are not well understood, particularly the mechanisms by which genetic diversity is lost or preserved as populations recover demographically. Here we examine how mating patterns and spatial considerations influence genetic diversity and structure in one of the few known naturally regenerating populations of a highly threatened North American forest tree, Juglans cinerea L. (butternut). Butternut regeneration is now rare throughout the native range, due to a pathogenic fungus, and an understanding of genetic processes during an episode of natural, in-situ seedling establishment may contribute to restoration efforts. Using direct and inferred parentage analyses, Bayesian clustering, and spatial genetic structure analysis of 116 adults and 36 juveniles with 12 microsatellite markers, we show that natural regeneration at this site resulted in loss of allele richness and a shift in genetic structure due to a small number of parents, most of which are spatially proximal to the regenerants. Of the 116 potential parents tested, one contributed 20.8% and the top four contributed 71.1 % of the gametes in regenerants, a remarkable dominance by a few parental trees. Parent-parent and parent-offspring distances revealed primarily limited pollen and seed dispersal (<100 m), but some instances of longer distance dispersal. Regenerants were highly related and spatially clustered in sibling groups. Proximity to the regenerating patch was the most significant factor in parental success. Our results suggest that in-situ regeneration of forest trees with limited propagule dispersal and specific site requirements may be insufficient to preserve native genetic diversity in protected areas with few and/or small suitable sites. We also discuss possible management actions that could contribute to retention of genetic diversity during regeneration in small sites.
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Sean Hoban Research
1 - Universita Di Ferrara, Dipartimento Di Biologia Ed Evoluzione, Via L. Borsari, 46, Ferrara Italy, N/A, 44100, France
2 - The University of Tennessee, Department of Forestry, Wildlife & Fisheries, Knoxville, TN, USA
3 - Frostburg State University, Biology, Frostburg, MD, 21532, USA
4 - University of Notre Dame, Biological Sciences, Notre Dame, IN, 46556, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Delaware B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 9:15 AM