Summary – The New Taxonomy- the molecular approach to orchid classification. Dr. Stewart McConnell


Dr Stewart McConnell’s talk centred on changes to plant classification following the relatively recent application of DNA analysis. Historically, the parameter used for identifying and distinguishing species was largely morphology – the study of plant form, and this, for many centuries, has enabled great advances in our understanding of plant relationships. However, some unrelated plants exhibit parallelism; that is, they have evolved along similar lines in response to various factors and thus share similar morphology. As a result, shared morphology does not necessarily reflect common ancestry. The use of molecular techniques and maximum parsimony analysis enables the researcher to erect a tree or cladogram (with each species under consideration at the end of the branches). They are thus able to propose the most likely evolutionary route taken by a single or group of species and the number of mutations that this would have entailed. Recently, the use of such modelling and powerful computers has, despite a degree of subjectivity inherent to the technique, resulted in increasingly reliable results, especially when used in conjunction with classical disciplines such as morphology and anatomy. Molecular biologists are currently attempting to refine this valuable technique and adopt a multidisciplinary approach.