Atypical development in plant and soil nematodes.

Observations of atypical developmental and anatomical characteristics have been recorded for many taxa of soil nematodes. They include the unusual occurrence of extra feeding structures, aberrant configuration of features of both male and female reproductive systems, and the occurrence of intersexes assumed to be functionally female, functionally male, or non-functional. In many cases, hypotheses have been advanced regarding the genetic or developmental mechanisms and environmental stimuli that control, regulate, or facilitate abnormalities, but many are quite speculative and lack experimental verification. Further, the fitness costs or advantages, and the heritability of aberrant characters are largely unknown, except where they clearly preclude reproduction, either apomictic or amphimictic. Underlying mechanisms and ecological consequences may be difficult to study in organisms that are not readily cultured under axenic or sterile laboratory conditions, however information on developmental processes in Caenorhabditis elegans represents an important resource in which to seek homologies.