Discrimination of 2n = 60 <i>Spalax leucodon</i> cytotypes (Spalacidae, Rodentia) in Turkey by means of classical and molecular cytogenetic techniques

Abstract

Comparative studies among seven populations of 2n = 60 S. leucodon employing classic cytogenetics (G- bands, C-bands, AgNOR-staining), fluorochrome staining, and fluorescence in situ hybridization of telomeric and rDNA probes are reported here for the first time. The studied specimens were assigned to two cytotypes: 2n = 60W and 2n = 60R. The basic karyotype of both cytotypes consisted of eight pairs of subtelocentric and 21 pairs of acrocentric autosomes, subtelocentric X and acrocentric Y chromosomes. Both cytotypes had variable numbers of B-chromosomes (1–3) and variable numbers of autosomal arms (NFa = 74–76) caused by amplification (deletion) of heterochromatin short arms in the second pair. The short arms of subtelocentric chromosomes were comprised of heterochromatin in both cytotypes. Nucleolar organizer regions (NORs) and rDNA clusters were detected at telomeric sites of the short arms in pairs Nos. 3, 5, 6, 9, and 13 in cytotype W, and in the short arms of pair No. 6, 8, 12, 13, and 16 in cytotype R. Different locations of rDNA clusters allowed unambiguous discrimination between two S. leucodon cytotypes possessing the same 2n = 60 and similar NFa (74–76) variability. Our findings suggest a high level of chromosomal divergence, which means that it is possible to consider these cytotypes as a well-differentiated, chromosomal lineage within the leucodon group.

Chromosomal evolution of the Genus Nannospalax (Palmer 1903) (Rodentia, Muridae) from western Turkey

“…Most chromosomal races are, however, differentiated without a barrier. Although chromosomal races are close together geographically in Turkey, hybridization does not occur (Nevo et al, 1994;Coşkun, 2003;Sözen, 2004;Matur and Sözen, 2005;Sözen et al, 2006aSözen et al, , 2006bKankılıç et al, 2007;Ivanitskaya et al, 2008). We neither recorded any hybrid specimens in the study area nor found polymorphism in G-and C-banding patterns.…”

“…Previous banding studies (Ivanitskaya et al, 1997(Ivanitskaya et al, , 2008) suggested a high level of chromosomal divergence, which means that it is possible to consider these chromosomal races as having well-differentiated chromosomal lineage within the xanthodon group. Our phylogenetic tree indicates that each group (west, north, middle, and Thrace) is well differentiated (Figure 5).…”

“…Currently more than 30 chromosomal races have been determined in Turkish blind mole rats but there is still doubt about the taxonomy of this taxon (Nevo et al, 1994;Sözen et al, 1998aSözen et al, , 1998bSözen et al, , 1999Sözen et al, , 2000aSözen et al, , 2000bSözen et al, , 2006aSözen et al, , 2006bSözen et al, , 2011Sözen, 2004;Matur and Sözen, 2005;Kankiliç et al, 2007;Ivanitskaya et al, 2008;Arslan et al, 2011). Kandemir et al (2012) discussed the taxonomic name problem of blind mole rats and so here we will follow Kandemir et al (2012).…”

“…So far, only a few banding studies of Turkish N. nehringi have been performed. These were conducted in populations from Malatya (Ivanitskaya et al, 1997) and Kastamonu and Çankırı provinces (Ivanitskaya et al, 2008). Additionally, a banding study was performed by Ivanitskaya et al (1997) with southeastern Anatolian blind mole rats (N. ehrenbergi) using G-, C-, and AgNOR-banding techniques.…”

“…Additionally, a banding study was performed by Ivanitskaya et al (1997) with southeastern Anatolian blind mole rats (N. ehrenbergi) using G-, C-, and AgNOR-banding techniques. Ivanitskaya et al (2008) assigned the 2n = 60 populations in Turkey to 2 chromosomal races as 2n = 60W and 2n = 60R, based on G-bands, C-bands, AgNOR staining, fluorochrome staining, and FISH of telomeric and rDNA probes. They assumed that ancestral karyotype diverged into the 2n = 60W and R chromosomal races, and independent translocations of short arms of some chromosomes caused this differentiation.…”