Nematodes have been most successful in colonizing soils and marine sediments: it is the only major metazoan group which is persistently abundant and diverse across realms. In marine sediments of shallow waters, nematodes are present at densities between 0,5 and 5 million individuals per m2 (Soetaert et al., 2009). In soil, the number of nematodes under non-extreme environmental conditions ranges from 2-20 million individuals per m2 (Bongers, 1994). In both soil and marine sediments, the density of other, second most abundant metazoans, including polychaetes and harpacticoid copepods in marine sediments, and mites and springtails in terrestrial soils, are about an order of magnitude lower. These data about nematode abundance and diversity prompt questions about the factors underlying the ecological success of this rather basal Ecdysozoan group. One of the main factors contributing to their ecological success could be their ecological flexibility. Using a phylum-wide SSU rDNA data base harbouring over 3,500 taxa allowed us to pinpoint at least 30 major habitat transitions. In Clades 1-6 (formerly referred to as Adenophorea) these transitions were bidirectional, whereas most likely members of Clades 8-12 (previously known as Secernentea) showed exclusively transitions from terrestrial to marine systems. We relate these transitions to the evolution and diversification of the secretory-excretory (S-E) systems as well as to feeding habits. Their ability to feed on types of food sources that are available both in soils and marine sediments such as bacteria, protists, and other nematodes, and to parasitize organismal groups present in both systems including lower and higher plants as well as a wide range of (in)vertebrates will have contributed to the ecological flexibility and the evolutionary success of nematodes.
|Publication status||Published - 10 Sep 2018|
|Event||ESN Conference 2018 - Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium|
Duration: 9 Sep 2018 → 13 Sep 2018
|Conference||ESN Conference 2018|
|Period||9/09/18 → 13/09/18|
Helder, J., Schratzberger, M., & Holterman, M. H. M. (2018). The remarkably high number of transitions from marine to terrestrial habitats and vice versa as an adaptation that could have contributed to the ecological success of nematodes. Abstract from ESN Conference 2018, Ghent, Belgium.