Chromosomal evolution in Gekkonidae. I. Chromosome painting between Gekko and Hemidactylus species reveals phylogenetic relationships within the group

Abstract

Geckos are a large group of lizards characterized by a rich variety of species, different modes of sex determination and diverse karyotypes. In spite of many unresolved questions on lizards' phylogeny and taxonomy, the karyotypes of most geckos have been studied by conventional cytogenetic methods only. We used flow-sorted chromosome-specific painting probes of Japanese gecko (Gekko japonicus), Mediterranean house gecko (Hemidactylus turcicus) and flat-tailed house gecko (Hemidactylus platyurus) to reveal homologous regions and to study karyotype evolution in seven gecko species (Gekko gecko, G. japonicus, G. ulikovskii, G. vittatus, Hemidactylus frenatus, H. platyurus and H. turcicus). Generally, the karyotypes of geckos were found to be conserved, but we revealed some characteristic rearrangements including both fissions and fusions in Hemidactylus. The karyotype of H. platyurus contained a heteromorphic pair in all female individuals, where one of the homologues had a terminal DAPI-negative and C-positive heterochromatic block that might indicate a putative sex chromosome. Among two male individuals studied, only one carried such a polymorphism, and the second one had none, suggesting a possible ZZ/ZW sex determination in some populations of this species. We found that all Gekko species have retained the putative ancestral karyotype, whilst the fission of the largest ancestral chromosome occurred in the ancestor of modern Hemidactylus species. Three common fissions occurred in the ancestor of Mediterranean house and flat-tailed house geckos, suggesting their sister group relationships. PCR-assisted mapping on flow-sorted chromosome libraries with conserved DMRT1 gene primers in G. japonicus indicates the localization of DMRT1 gene on chromosome 6.

Chromosomal Characteristics of NORs and Karyological Analysis of Tokay Gecko, <i>Gekko gecko</i> (Gekkonidae, Squamata) from Mitotic and Meiotic Cell Division

“…1), namely, Cohen et al (1967), Singh (1974), De Smet (1981), Solleder and Schmid (1984), Wu and Zhao (1984), Trifonov et al (2011) and Qin et al (2012). The present study of the cytogenetics of G. gecko provides the first report on the Ag-NOR banding technique, size of chromosome, standardized idiogram and meiotic cell division which are compared to previous reports.…”

“…In spite of the great interest in reptilian karyotype evolution and sex determination, only about 10% of gekkonid species have been karyotyped (Trifonov et al 2011) and have been studied with conventional cytogenetic techniques, as well as Ag-NOR and C-banding techniques (Moritz 1984, Shibaike et al 2009). It was revealed that diploid chromosome numbers vary from 2n=38 to 2n=44 (Shibaike et al 2009), with most of the karyotypes composed of 2n=38 (Olmo 1986) (Table 1).…”

Are some chromosomes particularly good at sex? Insights from amniotes

“…Pokorná et al (2011) examined three species congeneric with G. hokouensis, and found Only in one species, Gekko hokouensis, does the same chromosome have a role in sex determination, suggesting this function arose independently, rather than being retained for~275 Ma. Mapping and painting data from Kawai et al (2009), Pokorná et al (2011), and Trifonov et al (2011; phylogeny after Gamble et al (2011) andRösler et al (2011) that a single acrocentric chromosome was marked by the chicken Z probe; however, sex chromosomes remain unidentified in these species (Gekko japonicus, Gekko vittatus, and Gekko ulikovskii). Trifonov et al (2011) used chromosome paints from G. japonicus to demonstrate that sex chromosomes in the tokay gecko, G. gecko, and the flat-tailed house gecko, Hemidactylus platyurus, are not homologous with those in chicken.…”

“…Mapping and painting data from Kawai et al (2009), Pokorná et al (2011), and Trifonov et al (2011; phylogeny after Gamble et al (2011) andRösler et al (2011) that a single acrocentric chromosome was marked by the chicken Z probe; however, sex chromosomes remain unidentified in these species (Gekko japonicus, Gekko vittatus, and Gekko ulikovskii). Trifonov et al (2011) used chromosome paints from G. japonicus to demonstrate that sex chromosomes in the tokay gecko, G. gecko, and the flat-tailed house gecko, Hemidactylus platyurus, are not homologous with those in chicken. In more distantly related gekkotans (a pygopod and a eublepharid), XXY sex chromosomes are also not homologous with the chicken Z, suggesting that those of G. hokouensis arose independently and more recently than the sex chromosomes of other gekkotans (Fig.…”

Genomic Structures of the kW1 Loci on the Z and W Chromosomes in Ratite Birds: Structural Changes at an Early Stage of W Chromosome Differentiation

“…camelus Z chromosome is largely identical to that of turtle chromosome 6 and snake chromosome 2 [Matsuda et al, 2005;Matsubara et al, 2006Matsubara et al, , 2012Kawai et al, 2007;Tsuda et al, 2007;Uno et al, 2012]. This finding strongly suggests that these reptilian Z sex chromosomes and the avian sex chromosomes derived independently from different autosomal pairs of their common ancestor, and the avian ancestral Z chromosome (= ratite Z) has been conserved in reptilian autosomes [Pokorná et al, 2012], although the Z chromosome of the Hokou gecko (Gekko hokouensis) exceptionally shares the homology with the chicken Z chromosome [Kawai et al, 2009], which is not found in other gekkotans [Trifonov et al, 2011;O'Meally et al, 2012]. This conserved homology has been also observed between the snake Z chromosomes and lacertilian autosomes in squamates [Srikulnath et al, 2009[Srikulnath et al, , 2013Vicoso et al, 2013b].…”