ADVANCES IN MOLECULAR SYSTEMATICS: A REVIEW

ADVANCES IN MOLECULAR SYSTEMATICS: A REVIEW

Dr. S. JOHN BRITTO, S.J
Principal
St. Joseph's College (Autonomous)
Tiruchirappalli 620 002

One of the most exciting developments in the past decade has been the application of nucleic acid data to problems in systematics. The term
molecular systematics is used to mean macromolecular systematics the use of DNA and RNA to infer relationships among organisms, technically, isozyme methods and flavonoid data are also molecular.Molecular techniques provide powerful tools for the study of evolution and phylogeny. Most data of relationships at the species level and above have so far come from the chloroplast genome and the highly repeated sequences of ribosomal RNA.

Future data are likely to come also from low copy number nuclear genes. New tools are continually being developed for the study of variation within and among conspecific populations, including methods of genome mapping. As these tools come into more widespread use, they will provide new insights into the processes of population level differentiation. No matter how powerful the molecular data, how ever, morphological data will remain critical for phylogenetic studies. The major questions in Plant systematics are still morphological. Questions about the origin of species, the mechanisms of diversification, ad the best way to classify that diversity all require understanding of morphology as well as phylogeny. We can now envision a time when robust phylogenies will have been constructed for all groups of plants, and the question of systematics will shift from What is the phylogeny of my group? to How did the morphological diversity arise?