Traditional taxonomy and molecular studies in the field of biodiversity of soil nematodes

DOUCET, M.E; LAX, P.

Congreso; Second International Congress of Tropical Nematology; 2009

Biodiversity of soil and freshwater nematodes is far from being fully understood. Numerous species continue to appear with particular characteristics regarding the taxonomical, biological and phylogenetic aspects, as well as their relationship with the environment. However, the number of research articles related to taxonomy (description of new or poorly known species) has been decreasing along with the number of nematode taxonomists. The emergence of molecular biology and its influence on biological sciences is remarkable in this complex situation. The molecular approach in research can be conceptually similar to that considered the “classical” one (basically the analysis of morphological and morphometrical characters) but design and practice of experiments are quite different. Molecular biology experiments require expensive equipment and reagents that are not easily available everywhere. For classical experiments a microscope, good ability to observe and adequate training are enough. Another element is competition among scientific journals, which privilege publication of non-descriptive articles. At the same time, descriptive taxonomy is usually confused with phylogenetic one. Genera and species of significantly different morphology, anatomy, morphometry, and hosts have been related from the molecular approach. Even though these organisms may be closely related when considering certain DNA regions using specific software, the synonimisation proposed is artificial. These observations do not intend to support a task regarded by many as in “danger of extinction”. Rather, they are intended to remind us that nematodes are still worms, mostly microscopic ones with different external and internal shapes and variable behaviour. Direct contact with the organism under study is essential. A good connection with the real situation should lead us to equally encourage the use of all the study tools to advance in the knowledge of biodiversity of this fascinating animal group.