The use of molecular techniques is increasingly important in the conservation biology of endangered species as a means of understanding the genetic structure and diversity present in populations. Recent developments in molecular techniques include a powerful new tool for generating DNA fingerprints and detecting genetic polymorphisms: amplified fragment length polymorphisms (AFLP). This technique uses PCR to amplify a random assortment of DNA restriction fragments generated using two enzymes. AFLP technology combines the reliability of restriction digestion of genomic DNA with the benefits of PCR-based assays by ligating primer recognition sequences, or adaptors, to the restricted DNA. Because of the amplification step, only a small amount of DNA is needed. The technique allows the characterization of a large number of genetic loci in a relatively short time frame and is reliable and reproducible. We present preliminary results of the application of AFLP technology to the endangered species, Isoëtes louisianensis (Louisiana quillwort), currently known in two parishes of southeastern Louisiana and eight counties in southern Mississippi. Genetic diversity appears to be low in many of the populations, especially those with small numbers of individuals. There appears to be a positive correlation between geographical distance and genetic distance. In a preliminary neighbor joining analysis based on three primer pairs (61 variable characters, 25 informative characters), individuals from the same populations and geographical locations cluster together at high bootstrap values.

Key words: AFLP, endangered species, genetic diversity, Isoëtes louisianensis