Mitochondrial DNA diversity in nematodes

The relatively small literature on mitochondrial DNA (mtDNA) diversity in n ematode species is summarized here. Nematodes show a wide range of overall genetic diversities and population genetic structures. Species-wide levels of diversity correlate strongly with the breeding system and other life cyc le features that control effective population size. Obligate outcrossers th at parasitize mobile vertebrate hosts are the most diverse, species having hermaphroditic stages are less so, and species having asexual reproductive stages appear even less diverse. Nevertheless, these conclusions are prelim inary because there exist so few data on DNA diversity in nematodes. What i s needed are more comparative studies using similar sampling designs and th e same DNA markers, including nuclear loci and further work with mtDNA.