Chromosomes of Australian lygosomine skinks (Lacertilia: Scincidae)

Donnellan, Stephen C.

doi:10.1007/bf00126227

Cited by 20 publications

(14 citation statements)

References 34 publications

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“…Notably, the heteromorphic sex chromosome pair in B. duperreyi (pair 7) is also the heteromorphic sex chromosome pair for the two other species in the genus, and also in a further 28 species spanning nine other genera of skinks within the subfamily Lygosominae (Hardy 1979;Donnellan 1985Donnellan , 1991Hutchinson and Donnellan 1992). Given this apparent conservation of the sex chromosome pair, the PCR sexing test developed for B. duperreyi could prove to be useful for a number of species.…”

Section: Discussionmentioning

confidence: 99%

Isolation and development of a molecular sex marker for Bassiana duperreyi, a lizard with XX/XY sex chromosomes and temperature-induced sex reversal

et al. 2009

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Sex determination in the endemic Australian lizard Bassiana duperreyi (Scincidae) is influenced by sex chromosomes and incubation temperature, challenging the traditional dichotomy in reptilian sex determination. Analysis of those interactions requires sex chromosome markers to identify temperature-induced sex reversal. Here, we report the isolation of Y chromosome DNA sequence from B. duperreyi using amplified fragment length polymorphism PCR, the conversion of that sequence to a single-locus assay, and its combination with a single-copy nuclear gene (C-mos) to form a duplex PCR test for chromosomal sex. The accuracy of the assay was tested on an independent panel of individuals with known phenotypic sex. When used on offspring from field nests, our test identified the likely occurrence of a low rate of natural sex reversal in this species. This work represents the first report of Y chromosome sequence from a reptile and one of the few reptile sex tests.

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Section: Discussionmentioning

confidence: 99%

Isolation and development of a molecular sex marker for Bassiana duperreyi, a lizard with XX/XY sex chromosomes and temperature-induced sex reversal

et al. 2009

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“…Indeed, in many lineages chromosome evolution occurred both via increases and decreases of diploid number or via Robertsonian and non-Robertsonian mutations (Olmo, 1986;Donnellan, 1991;Pellegrino, Rodrigues & Yonenaga-Yassuda, 1999). In addition, as noted by King (1984King ( , 1995 in the majority of vertebrates, including several reptiles, the major adaptive radiations have been accompanied by Robertsonian changes at variance with the construct of the canalization model.…”

Section: Causes and Mechanisms Of Chromosome Variability In Reptilesmentioning

confidence: 99%

Rate of Chromosome changes and Speciation in Reptiles

Olmo

2005

Genetica

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The chromosome changing rate (i.e. the number of chromosome rearrangements per million years) was studied in 1,329 reptile species in order to evaluate the karyological evolutionary trend and the existence of possible correlations between chromosome mutations and some aspects of the evolution of this class. The results obtained highlight the existence of a general direct correlation between chromosome changing rate and number of living species, although different trends can be observed in the different orders and suborders. In turtles, the separation of pleurodires from cryptodires was accompanied by a considerable karyological diversification. Among pleurodires, the evolution of the Chelidae and Pelomedusidae was also characterised by chromosome variation, while in cryptodires a marked karyological homogeneity is observed between and within infra-orders. Similarly there is no correlation between changing rate and species number in crocodiles, where the evolution of the families and genera has entailed few chromosome mutations. Chromosome variability was greater in lizards and snakes. In the formers variations in chromosome changing rate accompanied the separation of the infra-orders and the evolution of most of the families and of some genera. The origin of snakes has also been accompanied by a marked karyological diversification, while the subsequent evolution of the infra-orders and families has entailed a high level of chromosome variability only in colubroids. The karyological evolution in reptiles generally entailed a progressive reduction in chromosome changing rate, albeit with differences in the diverse orders and suborders. This trend seems to be consistent with the "canalization model" as originally proposed by Bickham and Baker in [Bickham, J.W.& R J. Baker, 1979. Bull. Carnegie Mus. Nat. Hist. 13: 70-84.] However, several inconsistencies have been found excluding that in this class the ultimate goal of chromosome variations was the achievement of a so-called "optimum karyotype'' as suggested by the above-mentioned theory. Other mechanisms could underpin chromosome variability in Reptiles. Among them a genomic composition more or less favourable to promoting chromosome rearrangements and factors favouring the fixation of a mutant karyotype in condition of homozygosis. Turtles and crocodiles would have a genome characterised by large chromosomes and a low level of chromosome compartmentalisation limiting the recombination and the frequency of rearrangements. A low rate of chromosome variability modifying little if at all the gene linkage groups would have favoured a conservative evolutionary strategy. In the course of evolution, lizards and snakes could have achieved a genome characterised by smaller chromosomes and a higher level of compartmentalisation. This would have raised the frequency of recombination and consequently an evolutionary strategy promoting a higher degree of variability and a greater level of speciation.

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“…However, the numerical predominance of 2n --32 karyotypes in Mabuya throughout its range (Table 1), as well as in other closely related genera (King, 1973;Dennellan, 1991a: also see below), does not seem to favor this view. To support this view, we need to postulate the frequent occurrence of karyotypic orthoselection (King, 1993) toward the increase of the chromosome number in various lineages, but the chromosome fission seems to be much more rare compared to the fusion in lygosomine karyotypes (e.g., Donnellan, 1991b;Ota et al, 1991). We assume that the ancestral karyotype of Mabuya was actually in the widely prevailing 2n -32 format, and that the chromosomal divergence has occurred chiefly through various pericentric rearrangements (Donnellan, 1991 a, b) and sometimes through fusions.…”

Section: Implications Of the Highly Diverged Karyotype Ofmentioning

confidence: 99%

Chromosomal variation in the scincid genus Mabuya and its arboreal relatives (Reptilia: Squamata)

et al. 1996

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Karyotypes of four East and Southeast Asian species of the genus Mabuya and representatives of three arboreal genera considered to be closely related to the genus (Apterygodon, Dasia and Lamprolepis) are examined. Mabuya rugifera and M. rudis possess 2n = 32 karyotypes, whereas M. longicaudata lacks one small chromosome pair, which makes its diploid number 30. The karyotype of M. macularia quadrifasciata from southern Thailand differs from any known scincid karyotypes, including a previously reported karyotype of the conspecific Indian population, in exhibiting a high diploid number (38) and a gradual change in size from large to small chromosomes. This suggests that M. macularia may consist of more than one biological species. Karyotypes of Apterygodon vittatus, Dasia olivacea and Lamprolepis smaragdinus, while exhibiting a close similarity to most Mabuya karyotypes, suggest the occurrence of slight rearrangements involving either the deletion of two small chromosome pairs (A. vittatus), or the change of centromeric positions in medium and small chromosomes (D. olivacea and L. smaragdinus).

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Chromosomes of Australian lygosomine skinks (Lacertilia: Scincidae)

Cited by 20 publications

References 34 publications

Isolation and development of a molecular sex marker for Bassiana duperreyi, a lizard with XX/XY sex chromosomes and temperature-induced sex reversal

Isolation and development of a molecular sex marker for Bassiana duperreyi, a lizard with XX/XY sex chromosomes and temperature-induced sex reversal

Rate of Chromosome changes and Speciation in Reptiles

Chromosomal variation in the scincid genus Mabuya and its arboreal relatives (Reptilia: Squamata)

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