Triploidy in Natural Populations of the Black Fly Cnephia Mutata (Malloch)

Abstract

Populations of Cnephia mutata in southern Ontario contain both diploid and triploid individuals. The diploid form is bisexual and lacks chromosomal polymorphism except for a rearrangement involved in its cytological sex determining mechanism. The triploids are parthenogenetic; they produce female progeny only and are highly heterozygous for inversions. The banding pattern of the salivary gland chromosomes of diploids and triploids is very similar; the identical standard sequence occurs in both. The complete lack of autosomal inversions in diploids contrasted with their abundance in triploids indicates that effective genetic exchange does not occur between the two forms; they are reproductively completely isolated, although opportunity for cross-mating would seem to exist. The origin of polyploid parthenogenetic forms in black flies is discussed and the view is favored that they are autopolyploid and automictic.

Triploidy in the Natural Population of the Psychodine Moth FlyPsychoda ParthenogeneticaTonnoir (Diptera: Psychodidae)

“…The triploidy found in P. parthenogenetica seems to confirm a complete thelytoky and hence the existence of two distinct forms, one thelytokous and the other bisexual. In fact only one possible alternative exists which could deny this affirmation, that the males be occasional triploid individuals generated by parthenogenesis, as it seems to occur in a species of Prosimulium (BASRUR and RoTHFELS 1959). This eventuality, however unlikely, cannot be excluded for the moment.…”

“…This may be attributed to the same genetic and biological causes which have produced the origin and successful development of the thelytoky, and perhaps to the competition of the same thelytokous form, at least at beginning. Anyhow the coexistence of the two forms on a wide range makes one think of a case very similar to the one of the simuliid Cnephia mutata (BASRUR and RoTHFELS 1959), a 'super-species' which includes two forms, a diploid bisexual one and a triploid thelytokous one. In this case also the two forms frequently coexist in the same biotope, but there is good evidence that they do not interbreed.…”

“…It was found in a number of species belonging to different families, although more frequently among the Chironomidae (SCHOLL 1956(SCHOLL , 1960LINDEBERG 1958;PoRTER 1971) and Simuliidae (BASRUR and RoTHFELS 1959). Within the Psychodinae, besides Psychoda parthenogenetica, VAILLANT ( 1971) reports three other species, Psychoda phalenoides, P. lativentris and P. moravica, in which this mode of reproduction seems to be present.…”

“…The whole history of this debated question is reported in a recent paper of SALAMANNA (1975). Although a parthenogenetical generation of males is an unlikely event, which has been reported only once within the Diptera (BASRUR and RoTHFELS 1959), it is plain that the taxonomic problem exists. Only it has been stated perhaps wrongly.…”

A new hypothesis for the origin of the parthogenetic grasshopper Moraba virgo

“…Quite convincing examples exist in the simuliid Cnephia mutata (Basrur and Rothfels, 1959), in the lizard genera Cnemidophorus and Lacerta (e.g. Darevsky and Danielyan, 1968;Lowe et al, 1970), in the fish Poeciliaforniosa (Abramoff et al, 1968) and Poeciliopsis (Schultz, 1969), and in the Salamander Ambystoma "jeffersonianum" complex (Uzzell and Goldblatt, 1967).…”