Genetic Diversity in Southeastern Rare and Endangered Plant Species

Attempts to conserve or restore populations of an endangered species will only be successful if the species’ biology is well enough known to allow conservation biologists to make intelligent decisions. Information on the levels and distribution of genetic diversity is, therefore, desirable before any restoration or conservation effort is undertaken. Ideally, demographically and genetically healthy populations can be used to restore extinct or depleted populations. Over the last several years Dr. M. J. Godt and I have studied the genetic structure of several rare and endangered plant species from the southeastern U.S. These studies have included species from many diverse habitats (rocky cliff faces, bogs, rich forests) and from many plant families. Where possible we attempt to make collections from as many populations as possible throughout the known range of the species. Generally, these rare species maintain less genetic diversity within their populations than more widespread species. However, some rare species maintain unusually high levels of genetic diversity. Comparisons of the rare species with their more widespread, closely related congeners have shown that rare species often have a subset of the alleles of their more common relatives. This observation is consistent with the explanation that the rare species are habitat specialists that have recently evolved from the more widespread species. Rare species with unique alleles and higher levels of genetic diversity may, on the other hand, be older, once more widespread species.

Additional Research Projects

Genetic Consequences of Pre-Columbian Agave Cultivation

Although its ethnobotanical importance in Mexico and Central America has been long recognized, Agave cultivation by pre-Columbian indigenous peoples north of the Mexican border was documented less than 30 years ago. Recently, pre-Columbian Agave cultivation in Central Arizona has received more attention but many questions remain. Molecular techniques are used to examine both cultural and evolutionary aspects of Agave cultivation in this region. Specifically, a combination of allozyme, microsatellite, cpDNA and ribosomal DNA analyses are used 1) to determine levels of genetic variability within and among populations of two cultivars, A. murpheyi and A. delamateri, 2) to clarify the number of independent introductions of the two species into central Arizona from Mexico, 3) to identify their progenitors and possible routes of introduction, 4) to determine whether human selection for different traits in A. murpheyi differed with cultural context, 5) to compare levels and partitioning of genetic diversity within wild and cultivated populations of A. parryi and 6) to determine whether cultivated populations of A. parryi were derived from the same founder.

Conservation and Sustainable Use of Moringa peregrina

Moringa peregrina is a highly nutritious tree that produces economically valuable oil in addition to its benefits as a medicinal plant, water purifier and animal fodder. However, due to overgrazing and over-harvesting this drought resistant tree has become one of the most endangered plant species in Egypt. A collaborative research project with Saad Zaghaul (Suez Canal University, Ismailia, Egypt) will assist the conservation of this rare species and will preserve its key role in the desert ecosystem of the Southern Sinai. The project has these objectives: 1) to study the biology of the species in its natural ecosystem; 2) to study the level and distribution of genetic variation for several types of traits (morphometric, allozyme, cpDNA); 3) to determine the heritability of economically important traits (eg. pod and oil production); 4) to preserve M. peregrina in its natural habitats; 5) to reestablish this tree in natural habitats; 6) to develop protocols to reproduce M. peregrina by different methods; 7) to increase public awareness concerning the importance of this tree and its benefits; 8) to transfer scientific knowledge about the tree in a format that can be used to train local Bedouins to grow and establish M. peregrina in natural habitats as well as cultivated orchards; 9) to increase the participation of the local Bedouin in ongoing conservation activities as the only assurance for sustained conservation.

Burke, J.M. and J.L. Hamrick. 2002. Genetic variation and evidence of hybridization in the genus Rhus (Anacardiaceae). Journal of Heredity 93:37-41.
Godt, M. J. W. and J. L. Hamrick. 1998. Allozyme diversity in the endangered pitcher plant Sarracenia rubra ssp: alabamensis (Sarraceniaceae) and its close relative S. rubra ssp rubra. American Journal of Botany 85:802-810.
Godt, M. J. W. and J. L. Hamrick. 1999. Population genetic analysis of Elliottia racemosa (Ericaceae), a rare Georgia shrub. Molecular Ecology 8:75-82.
Godt, M. J. W. and J. L. Hamrick. 1999. Genetic diversity in rare southeastern plants. Natural Areas Journal 21:61-70.