Geneticist, Senior Scientist Emeritus
Contact Tom Ledig
My research is primarily in conservation genetics and evolutionary biology, specifically, (1) the conservation genetics and mating systems of rare Mexican spruces and pinon pines and (2) the recent evolutionary history and biogeography of Californian conifers. We use isozymes and field tests to investigate natural populations of forest trees. In the conservation of plant species, the choice to protect or neglect often depends on taxonomic status, and our research frequently begins with phylogenetic questions and proceeds to studies of genetic structure and mating systems. We reconstruct evolutionary history and determine the processes (selection, mutation, genetic drift, migration) that shape a species' genetic structure. The objective is to develop principles for the conservation of biodiversity, based on studies of the genetic structure of endemics, which are models for species fragmented by loss of habitat.
A line of research that is of secondary interest is provenance and progeny testing of eucalypt species for renewable biomass energy crops on abandoned agricultural land in California. The research on Mexican conifers and eucalypts necessarily involves a number of international collaborators.
I am an adjunct professor in the Department of Plant Science, University of California-Davis. I am also a member of the Forest Genetic Resources Working Group (FGRWG) of the North American Forest Commission/FAO/UN http://www.fs.fed.us/global/nafc/genetics/aboutus.htm. The role of the FGRWG is to advise the North American Forest Commission (the chiefs of the Canadian, U.S., and Mexican agencies responsible for forests) with respect to genetic resources. The Group's primary objectives are to encourage and promote collection, exchange, and dissemination of information, and to coordinate programs of research, conservation, and training among the countries of North America
- North Carolina State University, Ph.D. Genetics; minor mathematics and statistics, 1967
- North Carolina State University, M.S. Genetics; minor forestry, 1965
- Rutgers University, B.S. Forestry; minor statistics, cumlaude, 1962
Publications & Products
- Ledig, F. Thomas; Rehfeldt, Gerald E.; Saenz-Romero, Cuauhtemoc; Celestino, Flores-Lopez . 2010. Projections of suitable habitat for rare species under global warming scenarios.
- Ledig, F. Thomas; Hodgskiss, Paul D.; Johnson, David R. 2010. The structure of genetic diversity in Engelmann spruce and a comparison with blue spruce.
- Jaramillo-Correa, Juan P.; Beaulieu, Jean; Ledig, F. Thomas; Bousqueter, Jean. 2006. Decoupled mitochondrial and chloroplast DNA population structure reveals Holocene collapse and population isolation in a threatened Mexican-endemic conifer..
- Ledig, F. Thomas; Hodgskiss, Paul D.; Johnson, David R. 2006. Genetic diversity and seed production in Santa Lucia fir (Abies bracteata),a relict of the Miocene broadleaved evergreen forest.
- Ledig, F. Thomas; Hodgskiss, Paul D.; Johnson, David R. 2005. Genetic diversity, genetic structure, and mating system of brewer spruce (Pinaceae), a relict of the acto-tertiary forest.
- Ledig, F. Thomas; Hodgskiss, Paul D.; Krutovskii, Konstanin V.; Neale, David B.; Eguiluz-Piedra, Teobaldo. 2004. Relationships among the spruces (Picea, Pinaceae) of southwestern North America.
- Ledig, F. Thomas; Hodgskiss, Paul D.; Jacob-Cervantes, Virginia. 2002. Genetic diversity, mating system, and conservation of a Mexican subalpine relict, Picea mexicana Martínez.
- Lee, Seok-Woo; Ledig, F. Thomas; Johnson, David R. 2002. Genetic variation at allozyme and RAPD markers in Pinus longaeva (Pinaceae) of the White Mountains, California.
- Ledig, F. Thomas; Capó-Arteaga, Miguel A.; Hodgskiss, Paul D.; Sbay, Hassan; Flores-López, Celestino; Conkle, M. Thompson; Bermejo-Velázquez, Basilio. 2001. Genetic diversity and the mating system of a rare Mexican Piñon, Pinus pinceana, and a comparison with Pinus maximartinezii (Pinaceae).
- Criddle, Richard S.; Anekonda, Thimmappa S.; Tong, Sharon; Church, John N.; Ledig, F. Thomas; Hansen, Lee D. 2000. Effects of climate on growth traits of river red gum are determined by respiration parameters.
- Ledig, F. Thomas. 2000. Founder effects and the genetic structure of coulter pine.
- Ledig, F. Thomas; Bermejo-Velázquez, Basilio; Hodgskiss, Paul D.; Johnson, David R.; Flores-López, Celestino; Jacob-Cervantes, Virginia. 2000. The mating system and genic diversity in Martínez spruce, an extremely rare endemic of México’s Sierra Madre Oriental: an example of facultative selfing and survival in interglacial refugia.
- Ledig, F. Thomas; Conkle, M. Thompson; Bermejo-Velázquez, Basilio; Eguiluz-Piedra, Teobaldo; Hodgskiss, Paul D.; Johnson, David R.; Dvorak, William S. 1999. Evidence for an extreme bottleneck in a rare Mexican pinyon: genetic diversity, disequilibrium, and the mating system in Pinus maxamartinezii.
- Ledig, F. Thomas. 1999. Genic diversity, genetic structure, and biogeography of Pinus sabiniana Dougl..
- Ledig, F. Thomas; Vargas-Hernández, J. Jesús; Johnsen, Kurt H. 1998. The conservation of forest genetic resources: case histories from Canada, Mexico, and the United States.
- Ledig, F. Thomas; Neale, David B. 1998. World directory of forest geneticists and tree breeders.
- Ledig, F. Thomas; Jacob-Cervantes, Virginia; Hodgskiss, Paul D. 1997. Recent evolution and divergence among populations of a rare Mexican endemic, Chihuahua spruce, following holocene climatic warming.
- Ledig, F. Thomas; Kitzmiller, J.H. 1992. Genetic strategies for reforestation in the face of global climate change.
- Ledig, F. Thomas. 1992. Human impacts on genetic diversity in forest ecosystems.
- Millar, C. I.; Ledig, F. T.; Riggs, L. A. 1990. Conservation of diversity in forest ecosystems.
- Gladstone, W.T.; Ledig, F. Thomas. 1990. Reducing pressure on natural forests through high-yield forestry.
- Ledig, F. Thomas. 1988. The conservation of diversity in forest trees.
- Kuser, John E.; Ledig, F. Thomas. 1987. Provenance and progeny variation in pitch pine from the Atlantic Coastal Plain.
- Emery, B.M.; Ledig, F. Thomas. 1987. Provenance variation in Eucalyptus camaldulensis Dehnh. in California.
- Bush, Robin M.; Smouse, Peter E.; Ledig, F. Thomas. 1987. The fitness consequences of multiple-locus heterozygosity: the relationship between heterozygosity and growth rate in pitch pine (Pinus rigida Mill.).
- Ledig, F. Thomas. 1986. Conservation strategies for forest gene resources.
- Strauss, Steven H.; Ledig, F. Thomas. 1985. Seedling architechture and life history evolution in pines.
- Strauss, Steven H.; Ledig, F. Thomas. 1985. Seedling architecture and life history evolution in pines.
- Ledig, F. Thomas; Korbobo, Donald R. 1983. Adaptation of sugar maple populations along altitudinal gradients: photosynthesis, respiration, and specific leaf weight.
- Standiford, Richard B.; Ledig, F. Thomas. 1983. Economic evaluation of Eucalypt energy plantations.
- Ledig, F. Thomas. 1983. Eucalypt Improvement for California: Progress and Plans.
- Ledig, F. Thomas; Conkle, M. Thompson. 1983. Gene diversity and genetic structure in a narrow endemic, torrey pine (Pinus torreyana Parry ex Carr.).
- Standiford, Richard B; Ledig, F Thomas. 1983. Proceedings of a work-shop on Eucalyptus in California, June 14-16, 1983, Sacramento, California.
- Ledig, F. Thomas; Guries, Raymond P.; Bonefeld, Barbara A. 1983. The relation of growth to heterozygosity in pitch pine.
- Guries, Raymond P.; Ledig, F. Thomas. 1982. Genetic diversity and populations structure in pitch pine (Pinus rigida Mill.).
- Guries, Raymond P.; Ledig, F. Thomas. 1981. Genetic structure of populations and differentiation in forest trees.
- Ledig, F. Thomas; Whitmore, J.L. 1981. Heritability and genetic correlations for volume, foxtails, and other characteristics of Caribbean pine in Puerto Rico.
- Drew, Allen P.; Ledig, F. Thomas. 1981. Seasonal patterns of CO2 exchange in the shoot and root of loblolly pine seedlings.
- Ledig, F. Thomas; Smith, D.M. 1981. The influence of silvicultural practices on genetic improvement: height growth and weevil resistance in eastern white pine.
- Ledig, F. Thomas; Porterfield, Richard L. 1981. West Coast tree improvement programs: a break-even, cost-benefit analysis.
- Drew, A.P.; Ledig, F. Thomas. 1980. Episodic growth and relative shoot:root balance in loblolly pine seedlings.
- Manley, S.A.M; Ledig, F. Thomas. 1979. Photosynthesis in black and red spruce and their hybrid derivatives: ecological isolation and hybrid adaptive inferiority.
- Ledig, F. Thomas; Clark, Joseph G.; Drew, Allen P. 1977. The effects of temperature treatment on photosynthesis of pitch pine from northern and southern latitudes.
- Ledig, F. Thomas. 1976. An analysis of methods for the selection of trees from wild stands.
- Ledig, F. Thomas; Drew, A.P.; Clark, J.G. 1976. Maintenance and constructive respiration, photosynthesis, and net assimilation rate in seedlings of pitch pine (Pinus rigida Mill.).
- Fryer, John H.; Ledig, F. Thomas. 1972. Microevolution of the photosynthetic temperature optimum in relation to the elevational complex gradient.
- Ledig, F. Thomas; Fryer, John H. 1971. A pocket of variability in Pinus rigida.
- Ledig, F. Thomas; Bormann, F. Herbert; Wenger, Karl F. 1970. The distribution of dry matter growth between shoot and roots in loblolly pine.
- Ledig, F. Thomas; Wilson, Robert W.; Duffield, John W.; Maxwell, Gerald. 1969. A discriminant analysis of introgression between Quercus prinus L. and Quercus alba L..