Chromosomal variation in Agromyzidae (Diptera)

Abstract

The polytene chromosomes from the gastric coeca of Cerodonta (Butomomyza) eucaricis Nowakowski are described. There are five long and one dot‐like chromosome, the latter with indistinct bands. The X chromosome is number 5 and shows an allocyclical behaviour: In male larvae the bands are less distinct and the whole chromosome is much shorter than in female larvae. A material of 1444 larvae has been cytologically investigated. From their chromosomal morphology they could be classified as belonging to two different semispecies or perhaps sibling species. 1061 larvae belonged to the first semispecies and 349 to the other. The two semispecies occur as a rule sympatrically and may hybridize in nature. The hybrids are fertile, at least to some extent. The semispecies differ in one fixed inversion in the X chromosome and in five floating autosomal inversions. The two semispecies do not share any polymorphisms, but by occasional hybridization inversions could be transferred from one of the two semispecies to the other. Possible mechanisms for reproductive isolation and taxonomic state are discussed.

Origin and evolution of Y chromosomes: Drosophila tales

“…The best outgroups for this purpose are the Steganinae subfamily (which belongs to the same Drosophilidae family) and sister families such as Ephydridae and Curtonotidae. Little is known about their chromosomes, and the limited data from more distant Acalyptrata families are contradictory, with one study suggesting that the Drosophilidae karyotype is highly derived [60], and another suggesting that it is ancestral [61]. An investigation of the karyotype of outgroups such as Ephydridae is clearly needed.…”

Parthenogenesis in Hexapoda: holometabolous insects

“…Thelytoky was also found in a few other families, for example, Agromyzidae, Ceratopogonidae, Chamaemyiidae, Ctenostylidae, Hybotidae, Lonchopteridae, and Simuliidae (Normark, ). In the Agromyzidae, for example, Phytomyza crassiseta Zetterstedt, 1860 was reported to contain both parthenogenetic and bisexual diploid populations as well as several thelytokous triploid strains (Block, ). Moreover, thelytokous parthenogenesis was found in another member of the same genus, Ph.…”