[Life Forms of Lampreys (Petromyzontidae) as a Manifestation of Intraspecific Diversity of Ontogenesis].

Some lamprey genera include the forms that have significantly different life cycles (the most well-known are the "anadromous" and "resident," or the "parasitic" and "nonparasitic" forms). The analysis of data on the genetic characteristics of these forms shows that, in some cases, the nonparasitic lampreys independently derived from the parasitic ones in different aqueous systems. These data, together with the results of morphological analysis as well as data on the distribution, ecology, hybridization, and observations ofjoint spawning of parasitic and nonparasitic forms show that these forms belong to the same species (except the resident forms that were isolated long ago).