Jenny
Guha
Jim
Sara
Tim S.
Zach
Tim E.
Cecilia
Jessie
BillForest Genetics
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Ongoing Projects Parentage and Dispersal Conservation of Genetic Diversity |
Recent Projects Genetic Diversity and Structure |
Black Walnut
The ultimate goal of this research is to clarify basic components of the black walnut mating system, including male reproductive variance and gene flow. We perform theoretical and empirical studies focused on clarifying the roles of population size, mating system, pollen dispersal, and isolation in the maintenance of genetic diversity in Black Walnut populations. Rates of gene flow among Black Walnut populations also are investigated within the contexts of both contiguous and fragmented landscapes. An additional goal of this research is to elucidate fine scale genetic structure in black walnut populations within continuous stands and semi-isolated habitat fragments. This research helps to elucidate the processes through which genetic diversity is distributed and conserved over time in black walnut populations.
Funding Source: USDA Forest Service, Purdue University
Personnel: Rodney Robichaud, Jeff Glaubitz , Jenny Fike
Publications:
Robichaud, R.L., J.C. Glaubitz, O.E. Rhodes, Jr. and K. Woeste. 2006. A robust set of black walnut microsatellites for parentage and clonal identification. New Forest. 32:179-196.
Collaborators: K. Woeste and C. Michler
Conservation of Genetic Diversity
Black walnut (Juglans nigra) is the most economically important fine hardwood growing in the Central Hardwoods Region of the United States, and each year tremendous financial resources are committed to its management by state and federal agencies. However, given current land-use practices and future trends, it appears that this species is declining as a resource in the wild. Although nurseries have disseminated walnut stocks widely across the landscape, little data exist pertaining to the roles played by plantations in the sustainability of this species, for example as reservoirs of genetic material. It is likely that the primary focus of nursery and reforestation programs has been on providing adequate numbers of seedlings to meet demand, rather than on the dual role that they might also play in sustaining the genetic resources of black walnut. Without further investigation and subsequent refinement of current management practices, the sustainability of the black walnut in managed landscapes is in peril. The goal of this research is to evaluate and refine current nursery and plantation establishment protocols for black walnut with the purpose of conserving its genetic and phenotypic variation. We believe that much of the variation present in wild populations of this species can be preserved, but this will require the development of programs that are founded in a clear understanding of the genetic and ecological consequences of particular management practices. Fortunately, much of the infrastructure for management of black walnut is already present, lacking only clear guidelines that specify both demographic and genetic strategies. Our systematic evaluation and refinement of black walnut management programs should serve as a model for sustainable management of other fine hardwoods such as oaks.
Funding Source: USDA Forest Service, Purdue University
Personnel: Jeff Glaubitz
Publications:
Glaubitz, J.C., R.L. Robichaud, K. Woeste and O.E. Rhodes, Jr., 2004. Towards guidelines for harvest intensities with minimal impact upon retained genetic diversity in central hardwood tree species. In: Yaussy D.A., D.M. Hix., R.P. Long and P.C. Goebel (eds) Proceedings, 14th Central Hardwood Forest Conference; 2004 March 16-19; Wooster, OH. General Technical Report NE-316. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station, pp. 395-403. [CD-ROM]
Aldrich, P.R., J.C. Glaubitz, G.R. Parker, O.E. Rhodes, Jr., and C.H. Michler. 2005. Genetic structure inside a declining old-growth forest. Journal of Heredity. 96:627-634.
Glaubitz, J.C., P.R. Aldrich, C.H. Michler and O.E. Rhodes, Jr. Influence of fine-scale spatial genetic structure on the magnitude of genetic diversity loss under group harvest. Conservation genetics. (submitted)
Collaborators: K. Woeste, C. Michler, P. Aldrich, G. Parker
Genetic Diversity and Structure
The ultimate goal of this research is to further our understanding of gene dynamics in Black Walnut populations in the central hardwoods region of United States and to elucidate relationships between genetic characters and economically important functional characteristics in this species. This research builds the foundation for future investigations of genetic diversity and structure in Black Walnut as well as for subsequent genetic mapping, genetic linkage, and tree improvement activities. We have developed microsatellite makers for Black Walnut, and initial estimates of levels of polymorphism and information content within and among geographically distinct populations of this species have been established. In addition, time consuming laboratory techniques including DNA extraction from multiple tissue types, PCR amplification of multiplexed microsatellite loci, and simultaneous genotyping of individuals over multiple loci have been optimized for maximum efficiency. In this research project, both microsatellite and chloroplast markers will be used for investigations of genetic diversity and variance partitioning within and among relic populations of Black Walnut in the central hardwoods region. These data will be used to elucidate patterns of recolonization and geneflow in this species subsequent to the last galciation even.
Funding Source: USDA Forest Service, Purdue University
Personnel: Erin Victory, Jeff Glaubitz
Publications:
Woeste, K., R.P. Burns, O.E. Rhodes, Jr., and C.H. Michler. 2002. Thirty polymorphic nuclear microsatellite loci from black walnut. Journal of Heredity. 93:58-60.
Victory, E., K. Woeste and O.E. Rhodes, Jr. 2004. History of black walnut genetics in North America. Pages 1-8 In C.H. Michler et al. Eds., Black Walnut in a New Century. Proceedings of the 6th Walnut Council Research Symposium. Gen. Tech. Rep. NC-243. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Research Station.
Victory, E., J.C. Glaubitz, O.E. Rhodes, Jr. and K. Woeste. 2006. Genetic homogeneity in Juglans nigra (Juglandaceae) at nuclear microsatellites. American Journal of Botany. 93:118-126.
Victory, E., J.C. Glaubitz, J.A. Fike, O.E. Rhodes, Jr. and K. Woeste. 2008. Different histories but similar genetic diversity and structure for black walnut in Indiana and Missouri. Pages 436-445 in D.F. Jacobs and C.H. Michler eds. Proceedings of the Sixteenth Central Hardwoods Forest Conference; 2008, April 8-10; Lafayette, USDA Forest Service Northern Research Station Technical Report NRS-P-24.
Collaborators: K. Woeste and C. Michler