Nematodes are known as one of the most speciose, abundant, and ubiquitous yet most poorly known of the major metazoan phyla on earth. In many habitats, the species richness of nematodes exceeds that of all other multicellular animals. Ironically, the tropical rainforest is known as a region of relatively low nematode biodiversity. The simplest explanation is that tropics have not been sampled adequately. Systematic sampling of vertical strata from soil and litter to arboreal habitats at La Selva resulted in 167 distinct MOTUs (molecular operational taxonomic unit) among the 360 nematode characterized. This project will tie the MOTUs to morphology and ecology for identification and delineation of nematode species identified in a preliminary survey. The focus will be on nematode taxa living in symbiosis (i.e., parasitism, mutualism and commensalism) with vascular and nonvascular plants, decaying plant debris, soil, epiphytes and invertebrates. As a country, Costa Rica has an unusually rich biodiversity that is seriously threatened by deforestation because of pressure of human population growth and economic expansion. The survey will establish a baseline for comparison of future conservation efforts in Costa Rica that require environmental monitoring. The timing of the study is urgent, especially in a time of rapid global climate change and habitat destruction.
