Abweichende Form der Parthenogenese bei einer Mutation von Rhabditis pellio

An advantage for the evolution of male haploidy and systems with similar genetic transmission

“…This is now a slight variation of IV, due to the lcw proportion of females which arise from mictic eggs (perhaps an unavoidable consequence of male heterogamety). Pseudogamy is known in several other rhabditids, including some hermaphrodites, but none of these are known to so closely exemplify IV as does R. monohystera (Hertwig, 1920;Triantaphyllou, 1976). In summarising the discussion of the four genetic systems, I and IV seem the most likely to arise and withstand the reversion to diploidy because both can occur parthenogenetically or with maternal control of paternal genome loss.…”

On the Evolution of Parthenogenesis in Lonchoptera (Diptera)

“…The evidence in other animals for a mutation conferring parthenogenetic ability in a single step is not at all clear. Hertwig's (1920) case of a strain of Rhabditis pellio which suddenly displayed parthenogenesis, presumably based on mutation or recombination, is probably not relevant, since in that species, as in related nematodes, pseudogamy existed, with the continuing need for stimulation of the egg by sperm, even though the sperm took no further part in development. If we grant the possibility of such a single all-important gene mutation as the source of parthenogenetic ability in· L. dubia, it would still have to be assumed that the mutant gene concerned was widely disseminated in the bisexual populations prior to loss of males, in order to account for the extensive present-day chromosomal variability.…”

Ricerche Sulla Ovogenesi e Sulla Fecondazione Nella PlanariaPolycelis NigraEhrenberg con Particolare Riguardo All'Ufficio del Nucleo Spermatico

“…F enomeni simili sono stati successivamente visti in altre specie dello stesso genere: P. HERTWIG ( 1920HERTWIG ( -1922 li ha illustrati particolarmente in Rhabditis pellio e BELAR ( 1923BELAR ( -1924 in Rh. monohystera.…”