Environmental sex determination in reptiles

Ciofi, Claudio; Swingland, Ian R.

doi:10.1016/s0168-1591(96)01108-2

Cited by 47 publications

(38 citation statements)

References 72 publications

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“…All snakes so far studied appropriately exhibit female heterogamety (e. g., Beçak et al, 1964;Beçak & Beçak, 1969;Singh, 1972), whereas there are both male (XX/XY) and female (ZZ/ZW) heterogamety in the lizards and turtles with GSD (Olmo and Signorino, 2005). Besides GSD or chromosomal sex determination (CSD), TSD is widespread in reptiles (Ciofi and Swingland, 1997). The mechanisms of sex determination and the primary factors of its complexity in birds and reptiles remain unknown (Sarre et al, 2004;Smith and Sinclair, 2004).…”

Section: Origins and Differentiation Of Sex Chromosomes In Reptilesmentioning

confidence: 99%

Different origins of bird and reptile sex chromosomes inferred from comparative mapping of chicken Z-linked genes

Kawai¹,

Nishida‐Umehara

Ishijima

et al. 2007

Cytogenet Genome Res

117

147

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Recent progress of chicken genome projects has revealed that bird ZW and mammalian XY sex chromosomes were derived from different autosomal pairs of the common ancestor; however, the evolutionary relationship between bird and reptilian sex chromosomes is still unclear. The Chinese soft-shelled turtle (Pelodiscus sinensis) exhibits genetic sex determination, but no distinguishable (heteromorphic) sex chromosomes have been identified. In order to investigate this further, we performed molecular cytogenetic analyses of this species, and thereby identified ZZ/ZW-type micro-sex chromosomes. In addition, we cloned reptile homologues of chicken Z-linked genes from three reptilian species, the Chinese soft-shelled turtle and the Japanese four-striped rat snake (Elaphe quadrivirgata), which have heteromorphic sex chromosomes, and the Siam crocodile (Crocodylus siamensis), which exhibits temperature-dependent sex determination and lacks sex chromosomes. We then mapped them to chromosomes of each species using FISH. The linkage of the genes has been highly conserved in all species: the chicken Z chromosome corresponded to the turtle chromosome 6q, snake chromosome 2p and crocodile chromosome 3. The order of the genes was identical among the three species. The absence of homology between the bird Z chromosome and the snake and turtle Z sex chromosomes suggests that the origin of the sex chromosomes and the causative genes of sex determination are different between birds and reptiles.

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Section: Origins and Differentiation Of Sex Chromosomes In Reptilesmentioning

confidence: 99%

Different origins of bird and reptile sex chromosomes inferred from comparative mapping of chicken Z-linked genes

Kawai¹,

Nishida‐Umehara

Ishijima

et al. 2007

Cytogenet Genome Res

117

147

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“…(9) Male heterogamety (XY or XXY) is known in turtles, (10) female heterogamety (ZW, ZZW, or ZWW) is known in snakes (11)(12)(13) and both are known in lizards. (14) Many species have GSD in the absence of any gross heteromorphy in the sex chromosomes.…”

Section: Introductionmentioning

confidence: 99%

The ends of a continuum: genetic and temperature‐dependent sex determination in reptiles

Sarre¹,

Georges²,

Quinn³

2004

BioEssays

276

259

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Two prevailing paradigms explain the diversity of sex‐determining modes in reptiles. Many researchers, particularly those who study reptiles, consider genetic and environmental sex‐determining mechanisms to be fundamentally different, and that one can be demonstrated experimentally to the exclusion of the other. Other researchers, principally those who take a broader taxonomic perspective, argue that no clear boundaries exist between them. Indeed, we argue that genetic and environmental sex determination in reptiles should be seen as a continuum of states represented by species whose sex is determined primarily by genotype, species where genetic and environmental mechanisms coexist and interact in lesser or greater measure to bring about sex phenotypes, and species where sex is determined primarily by environment. To do otherwise limits the scope of investigations into the transition between the two and reduces opportunities to use studies of reptiles to advance understanding of vertebrate sex determination generally. BioEssays 26:639–645, 2004. © 2004 Wiley Periodicals, Inc.

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“…In most animals, the traditional view was that sex determination results from (a) genotypic sex determination (GSD), in which sex is determined at the time of fertilization by genetic factors independent of environmental influence or (b) environmental sex determination (ESD), in which sex is determined by environmental factors that act after fertilization [Ciofi and Swingland, 1997]. ESD has been studied in a variety of vertebrates and invertebrates including fishes [Conover, 1984;Conover et al, 1992;Beamish, 1993;Baroiller et al, 1996;Luckenbach et al, 2003], crustaceans [Naylor et al, 1988;Bergström, 1997;McCabe and Dunn, 1997;Rigaud et al, 1997], reptiles [Bull, 1980;Ferguson and Joanen, 1983;Deeming and Ferguson, 1988;Ewert and Nelson, 1991;Janzen and Paukstis, 1991;Lang and Andrews, 1994], nematodes, rotifers, polychaetes, and echiurids [Korpelainen, 1990].…”

Section: Temperature-dependent Sex Determinationmentioning

confidence: 99%

“…Sex in many of these species is determined by incubation temperature, a type of ESD known as temperature-dependent sex determination (TSD) [reviewed in Bull, 1980]. TSD is particularly widespread in reptiles, occurring in all crocodilians, marine turtles, and tuatara examined to date and is common in freshwater turtles and lizards [Bull, 1980;Ewert and Nelson, 1991;Janzen and Paukstis, 1991;Cree et al, 1995;Ciofi and Swingland, 1997;Lance, 1997]. The sex determining mechanism is not known in many of the squamate reptiles and has been described in less than 10% of extant reptilian species.…”

Section: Temperature-dependent Sex Determinationmentioning

confidence: 99%

“…No clear relationship has emerged between TSD and GSD in squamate lineages [Viets et al, 1994;Wibbels et al, 1994]. TSD was thought to occur exclusively in species without sex chromosomes [Bull, 1980;Valenzuela et al, 2003] but is now known to co-occur with GSD in species within the lizard families Agamidae, Eublepharidae, Gekkonidae, Scincidae, and possibly the Lacertidae, Varanidae and Iguanidae [Viets et al, 1994;Ciofi and Swingland, 1997;Harlow and Shine, 1999;Quinn et al, 2007;Radder et al, 2008]. The existence of GSD and TSD in closely related species suggests that the sex determining systems are themselves closely related [Wibbels et al , 1994].…”

Section: Temperature-dependent Sex Determinationmentioning

confidence: 99%

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Viviparity and Temperature-Dependent Sex Determination

Robert

Thompson

2009

Sex Dev

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Although temperature-dependent sex determination (TSD) has been a ‘hot topic’ for well over 30 years, the discovery of TSD in viviparous taxa is recent. Viviparity and TSD was regarded unlikely on theoretical grounds as viviparity allows for high stable developmental temperatures through maternal basking. However, pregnant squamates of many species choose different body temperatures from non-pregnant females and males, and we now know that differential temperature selection by viviparous species with TSD allows for the production of sons or daughters. Three species of squamate reptiles (all are skinks) are now know to exhibit TSD. The physiological mechanism by which viviparous reptiles control the sex of their offspring is not understood, but exposure to different operational sex ratios in the adult population is a factor in some species. The functional role of sex steroid hormones in egg yolk and how the hormones are manipulated in utero is still an area requiring detailed investigation. Fast maturing squamate reptiles provide an excellent, but as yet underutilized, model system for studying the adaptive significance of TSD, and the occurrence of TSD in viviparous species requires substantially more work on a phylogenetically diverse range of species.

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Environmental sex determination in reptiles

Cited by 47 publications

References 72 publications

Different origins of bird and reptile sex chromosomes inferred from comparative mapping of chicken Z-linked genes

Different origins of bird and reptile sex chromosomes inferred from comparative mapping of chicken Z-linked genes

The ends of a continuum: genetic and temperature‐dependent sex determination in reptiles

Viviparity and Temperature-Dependent Sex Determination

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