Cytogenetic variability in three species of the genus Cicindela (s.l.) (Coleoptera, Cicindelidae): karyotypes and localization of 18S rDNA genes

Abstract

Three tiger beetle species from the Cicindelini tribe were examined cytogenetically and found to have the following karyotypes: Cicindela argentata, 2n = 18 + X 1 X 2 Y/X 1 X 1 X 2 X 2 ; Cicindela aurulenta, 2n = 18 + X 1 X 2 X 3 Y/X 1 X 1 X 2 X 2 X 3 X 3 and Cicindela suturalis, 2n = 18 + X 1 X 2 X 3 X 4 Y/X 1 X 1 X 2 X 2 X 3 X 3 X 4 X 4 . Fluorescence in situ hybridization (FISH) using a PCR-amplified 18S rDNA fragment as a probe showed the presence of ribosomal clusters in two autosomes in C. argentata, two autosomes and two heterosomes in C. aurulenta and in two heterosomes in C. suturalis (male configuration), revealing two new patterns of rDNA localization. Such results are representative of the cytogenetic variability observed in the species rich genus Cicindela (sensu lato) mainly as regards the localization of rDNA genes and the number and morphology of the heterosomes, in spite of the stability of autosome numbers. Changes in the localization and number of rDNA clusters were independent of changes in the number of sex chromosomes, indicating that several processes might have contributed to the great karyotypic diversity found within this speciose Coleopteran group.

Chromosomal similarities and differences among four Neotropical Elateridae (Conoderini and Pyrophorini) and other related species, with comments on the NOR patterns in Coleoptera

“…In related beetle species, alterations in the NOR distribution patterns could be responsible for karyotypical differentiations, occurring as a unique event or concomitant with variations in the diploid number and type of sex-determination system. The last situation seems to have occurred in the subfamily Cicindelinae (Adephaga), in which the chromosomal derivations, from the basal to the derivative taxa, have given rise to multiple sex-determination systems and have shifted the NORs from autosomes to sex chromosomes (Galia´n and Hudson 1999;Galia´n et al 2002;Proenc¸a et al 2002b;Proenc¸a and Galia´n 2003;Proenc¸a et al 2004;Zacaro et al 2004). Go´mez-Zurita et al (2004), analysing some representatives of the Timarcha genus (Chrysomelidae, Polyphaga), also verified the presence of NORs on the sex chromosome, but only in species that possesses the derivative sex-determination system of the neoXY type.…”

A historical review of the studies of Neotropical tiger beetles (Coleoptera: Cicindelidae) with special reference to their use in biodiversity and conservation

“…Investigations of chromosomes, genes and molecules have become critical for understanding many other aspects of Neotropical tiger beetles from phylogeny to evolution of adaptations. The unique nature of tiger beetle sex chromosomes has been especially useful in reconstructing evolutionary trends (Serrano & Yadav, 1984;Proença et al, 1999Proença et al, , 2004Galián et al, 2002), and studies at the molecular level (Vogler & DeSalle, 1994;Vogler & Pearson, 1996;Vogler et al, 1997Vogler et al, , 2005Pons & Vogler, 2006) have opened up areas of investigation that have implications for many other organisms.…”

Chromosome evolution in tiger beetles: Karyotypes and localization of 18S rDNA loci in Neotropical Megacephalini (Coleoptera, Cicindelidae)

“…On the other hand, Cicindelidae species belonging to the Collyrini, Ctenostomini and Cicindelini tribes have been described as having a diverse multiple sex chromosome system, XnY, where n varies from two to four (Serrano and Galián, 1998;Galián and Hudson, 1999;Proença et al, 1999aProença et al, , b, 2002aProença et al, , 2004Galián et al, 2002;Zacaro et al, 2004). These heterosomes form a characteristic rosette-like multivalent during pairing at diakinesis and metaphase I, linked by telomeric connections without forming chiasmata between the various X chromosomes (Giers, 1977).…”