A review of the use of allozyme electrophoresis in plant systematics

The role of electrophoretic data is discussed as it applies to plant taxono my and systematic studies. Nei's (Am. Nat. 106 (1972) 283-292: Genetics 89 (1978) 583-590) genetic distances calculated for a large number of populati ons. species and genera were taken from published data. The relation betwee n Nei's genetic identity measures and taxonomic rank (populations. species and general;Ire shown graphically. The graphs obtained in this: way (from 3 021 pairs of plant taxa) differ substantially from previous graphs publishe d by Thorpe (Ann. Rev. Ecol. Syst. 13 (1982) 139-168, in: G.S. Oxford. D. R ollinson (Eds.). Protein Polymorphism: Adaptive and Taxonomic Significance. Academic Press. London. 1983. pp, 131-152) and Thorpe and Sole-Cava (Zool. Scripta 23 (1994) 3 18). These authors suggested that the divergence betwe en the different taxonomic ranks is roughly similar across a wide range of taxa. The latter was based on values for 2664 (Thorpe. 1982) and 8060 (Thor pe. 1983) pairs of animal and plant tars. but the plant data contributed li ttle to the total. For any given taxonomic rank. we round that plants are g enetically more closely related than animals (possibly; with the exception of birds). This result is important because the empirical relationships of genetic distance measures, to difTerent levels of taxonomic separation is o ften used for distinguishing and identifying cryptic or sibling species whe re convectional methods are unable to resolve systemnatic problems. (C) 200 1 Elsevier Science Ltd. All rights reserved.