Y-Chromosome Disomy and Trisomy in Scarabaeid and Cerambycid Beetles

Sarri

et al. 2019

Bull. Entomol. Res.

A dual molecular and cytogenetic study was performed with the aim to improve the controversial systematic classification of some species of Lamiinae (Coleoptera: Cerambycidae). The karyotypes of species belonging to genera Morimus, Herophila, Dorcadion, Neodorcadion and Lamia share a number of characters, which differentiate them from other species, belonging to genera Phytoecia, Parmena and Monochamus. The karyotypes of the last three species comprise 20 chromosomes, mostly metacentric or sub-metacentric, as in the presumed Cerambycidae ancestors. The karyotypes of the former species share many characters derived from the Lamiinae ancestors by a number of chromosome fissions and inversions indicating their monophyly. Comparisons of the CO1 gene sequence also show the monophyly of Morimus, Lamia, Herophila and Dorcadion and their distant relationship with others. These convergent results allow us to propose a phylogenetic classification of these genera, which places the monospecific genus Lamia close to Dorcadion, clearly separates Dorcadion and Neodorcadion and places Herophila closer to Morimus than to Dorcadion/Lamia. The genus Morimus is the most derived. CO1 mutations loosely separate the forms M. asper and M. funereus, which have similar karyotypes and behaviour and copulate in captivity. The form M. ganglebaueri may have a funereus X asper hybrid origin.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phylogenetic relationships between genera Dorcadion, Lamia, Morimus, Herophila and some other Lamiinae (Coleoptera: Cerambycidae) based on chromosome and CO1 gene sequence comparison

Giannoulis

Sarri

et al. 2019

Bull. Entomol. Res.

“…Most of them had XY sex chromosomes, but we found XYY males in about 1% of the specimens analysed [Dutrillaux and Dutrillaux, 2011]. In 24 species from 9 families, the males studied had an X0 sex formula.…”

Section: Resultsmentioning

confidence: 64%

“…It was supposed to be important for a correct segregation of the sex chromosomes at anaphase I, but as suggested by the multiple occurrences of XYY males, it is not unfailing [Dutrillaux and Dutrillaux, 2011]. The occurrence of X0 males is the expected reverse situation caused by the incorrect segregation of the Y.…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Sex Chromosomes in Beetles. I. The Loss of the Y Chromosome

Dutrillaux²

2017

Cytogenet Genome Res

In the males of Coleoptera, the most frequent sex chromosome constitution is XY. At metaphase I of meiosis, the X and Y are linked by nucleolar proteins, forming the so-called parachute bivalent (Xy_p), which is assumed to allow the non-synapsed X and Y to segregate correctly at anaphase I. However, X0 males are not exceptional, and we explored the relationships between the X and nucleolar proteins in the absence of the Y chromosome in 6 species belonging to different families/subfamilies. Using C-banding and silver staining, we show that nucleolar proteins always remain in contact with the X until anaphase I. These proteins are generally more abundant than in the Xy_p bivalent, may remain associated with the NOR during diakinesis, and frequently link the X to 1 or 2 autosomal bivalents, which seem to play the same role as the Y. This role may also be played by B chromosomes, which appear to be more frequent in X0 than in XY males. In conclusion, following Y chromosome loss, various strategies using nucleolar proteins have been developed to facilitate the migration of the unique X at meiotic anaphase I.

“…In other beetles, the rare increases in sex chromosome numbers are most often due to the gain of the Y chromosome. However, the accidental formation of the XYY male sex formulae, as that of X0, is caused by the non-disjunction of the faulty Xyp system of Coleoptera, and not by chromosome fission [27]. Fissions involving the X chromosome during evolution of beetles, as in other animals, seem to be very unusual and not formerly demonstrated.…”

Section: Chromosome Fission In New Caledonian Passalidae: An Exceptio...mentioning

confidence: 96%

Multiple Chromosome Fissions, Including That of the X Chromosome, in Aulacocyclus tricuspis Kaup (Coleoptera, Passalidae) from New Caledonia: Characterization of a Rare but Recurrent Pathway of Chromosome Evolution in Animals

Salazar

et al. 2023

Genes

The male karyotype of Aulacocyclus tricuspis Kaup 1868 (Coleoptera, Scarabaeoidea, Passalidae, Aulacocyclinae) from New Caledonia contains an exceptionally high number of chromosomes, almost all of which are acrocentric (53,X1X2Y). Unlike the karyotypes of other species of the pantropical family Passalidae, which are principally composed of metacentric chromosomes, this karyotype is derived by fissions involving almost all the autosomes after breakage in their centromere region. This presupposes the duplication of the centromeres. More surprising is the X chromosome fragmentation. The rarity of X chromosome fission during evolution may be explained by the deleterious effects of alterations to the mechanisms of gene dosage compensation (resulting from the over-expression of the unique X chromosome in male insects). Herein, we propose that its occurrence and persistence were facilitated by (1) the presence of amplified heterochromatin in the X chromosome of Passalidae ancestor, and (2) the capacity of heterochromatin to modulate the regulation of gene expression. In A. tricuspis, we suggest that the portion containing the X proper genes and either a gene-free heterochromatin fragment or a fragment containing a few genes insulated from the peculiar regulation of the X by surrounding heterochromatin were separated by fission. Finally, we show that similar karyotypes with multiple acrocentric autosomes and unusual sex chromosomes rarely occur in species of Coleoptera belonging to the families Vesperidae, Tenebrionidae, and Chrysomelidae. Unlike classical Robertsonian evolution by centric fusion, this pathway of chromosome evolution involving the centric fission of autosomes has rarely been documented in animals.