Karyotype evolution in the social wasps (Hymenoptera, Vespidae).

Abstract

The chromosomes of 21 species of Vespidae (consisting of 9 polistines and 12 vespines) were compared using an air-drying technique.The haploid number of the Polistinae ranged broadly (n=14, 22, 23, 26, 30, 31, and 34), while it was either n=25 or n=26 in the Vespinae. There were no karyological homologies (in terms of marker chromosomes) between these two subfamilies. Some phylogenetic relationships of social wasps were discussed, based on the karyological literature now available (32 species). We suggested that the three genera of Vespinae (Dolichovespula, Vespa, and Vespula) would have differentiated in two different ways from a common ancestor having 27 acrocentrics (n=27) by tandem fusion (the first genus with n=26) and by two centric fusions (the latter two genera with n=25).In the genus Polistes, the 5 subgenera (Fuscopolistes, Aphanilopterus, Megapolistes, Polistella, and Polistes) would have evolved independently toward increasing chromosome numbers since they started to separate from their ancestor having n=9-14.

Evolutionary dynamics of the karyotype of the wasp Trypoxylon (Trypargilum) nitidum (Hymenoptera, Sphecidae) from the Rio Doce State Park, Minas Gerais, Brazil

“…Although important in the process of heterochromatin elimination from the pseudoacrocentric chromosomes, this type of rearrangement is considered rare in the evolution of animal karyotypes (White, 1973). It was nevertheless observed by Imai et al (1994) in ant species of the Myrmecia pilosula complex, and was also identified in wasps of the genus Vespula by Hoshiba et al (1989) as one of the events in metacentric chromosome formation, by which pair 1A also seems to have been formed. However, in order to achieve greater karyotype stability, this pair of chromosomes may still be undergoing fission, as demonstrated by the one-armed heteromorphism pattern that, according to Imai et al (1994), is characteristic of this kind of rearrangement.…”

Diploid males in the bumble bee Bombus terrestris

“…For the chromosome counts, the reproductive organs from the last larval stage or from young pupa of both sexes were generally used. The chromosome preparations were made by lactic acid dissociation, a drying technique improved by Hoshiba et al (1989).…”

Notes on the Remarkable Karyology of the Primitive Ant Nothomyrmecia Macrops, and of the Related Genus Myrmecia (Hymenoptera: Formicidae)

“…It is of some interest that both mammals and ants exhibit an extremely wide range of chromosome number variation: 2n--6-92, and 2n--2-94 respectively (for details see Imai, 1988;and Hoshiba et al, 1989).…”