Genetic invasion: hybridization between native and non-native elms in Southwest Missouri.

The purpose of this study was to investigate and document potential hybridization between two species of elm in Greene Co., Missouri using molecular markers. Siberian elm (Ulmus pumila) is an invasive, fast-growing, drought tolerant plant native to Eastern Siberia, Northern China, Manchuria, and Korea. Slippery elm (Ulmus rubra) is native to Missouri and typically found in Riparian corridors or other moist sites. On a routine field trip, trees with intermediate characteristics between the two were found in Greene Co., Missouri, raising the question of the extent of hybridization in the area. To determine hybridization, we identified trees using morphological characteristics and then examined Amplified Fragment Length Polymorphisms (AFLPs). This DNA fingerprinting technique uses restriction enzymes to cut DNA into many fragments and primers to PCR-amplify specific fragments for analysis. The resulting pattern of markers can be used to identify species, individuals or populations. In preliminary analysis of elms from Taney and Greene Counties, at least 13 distinct markers were found to differentiate Siberian elm from slippery elm. Cluster analysis showed three main groups of elms: slippery, Siberian, and a group of intermediates that are probably hybrids. We conclude that not only are Siberian elms escaping and becoming naturalized; but they are hybridizing with native elms, and hybrids are escaping. In other words, Siberian elm appears to be diluting the genetic identity of our native slippery elm. Supported by an SMSU faculty research grant to L.M.B.

* Ladd, M., S. Snider, J. Lewis and L.M. Bowe. Department of Biology, Southwest Missouri State University.