Karyotype of the gecko, Gekko japonicus. This is clearly in error, McBee et al. Goniurosaurus species occur over a wide latitudinal gradient with G. J Biogeogr. Conclusions I have summarized current knowledge of gekkotan sex determination and have shown that at least 8 to 9 transitions among sex determining mechanisms have occurred during the last million years of gekkotan evolution.
Reptiles are an especially suitable group for such analysis as the sex-determining mechanisms, in squamate reptiles in particular, are variable. Allsop, unpubl. Table 1 Known examples of sex chromosomes in gekkotan lizards as determined by cytogenetic analyses.
Breeding leopard geckos is relatively easy and rewarding. Simultaneous hermaphroditism: male and female sexual organs coexist in one individual e. The multiple origins and large number of W chromosome variants make Heteronotia an excellent group to study sex chromosome evolution within Gekkota.
Cytotaxonomy and Vertebrate Evolution. On the organization of individual differences in sexual behavior. Solleder and Schmid, Temperature is the most common environmental cue in tetrapods, a phenomenon known as temperature-dependent sex determination TSD.
A widely held view is that temperature-dependent and genotypic sex determination are mutually exclusive, incompatible mechanisms—in other words, a reptile's sex is never under the influence of both sex chromosomes and environmental temperature. Sex determination in turtles: diverse patterns and some possible adaptive values.
These 2 genera were coded as either ZW or XY and their sex determining mechanisms were estimated as part of the analysis.
New developments in cytogenetics and genomics are making it easier to study sex determination in a variety of non-model organisms. To take full advantage of the potential that geckos hold as a model clade and to fully understand the processes involved in how transitions between sex determining mechanisms occur, requires knowledge of the pattern and distribution of these mechanisms in a phylogenetic context.
Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. See Subscription Options. Reproduction and the mechanism of meiotic restitution in the parthenogenetic lizard Cnemidophorus uniparens.
Chrom Inf Serv.