Effects of Incubation Temperature on Sex Determination in the Endangered Magdalena River Turtle,Podocnemis lewyana

Gómez-Saldarriaga, Catalina; Valenzuela, Nicole; Ceballos, Claudia P.

doi:10.2744/ccb-1170.1

Cited by 19 publications

(13 citation statements)

References 40 publications

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“…These can be broadly categorised into temperature-dependent sex determination, genetic sex determination [ 1 , 3 – 7 ] and systems where genotype and environment interact to determine sex [ 8 , 9 ]. Temperature-dependent sex determination (TSD)—where sex is determined by incubation temperature during the “thermosensitive period”—occurs in all crocodiles, many turtles, the tuatara, and seems to be the predominant mechanism of sex determination for lizards [ 10 – 15 ]. By contrast, genetically controlled sex determination (where genes on sex chromosomes determine sexual phenotypes; GSD) occurs in snakes and some lizards and turtles [ 3 , 16 – 20 ].…”

Section: Introductionmentioning

confidence: 99%

Sex determination mode does not affect body or genital development of the central bearded dragon (Pogona vitticeps)

Whiteley

Holleley

Ruscoe

et al. 2017

EvoDevo

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BackgroundThe development of male- or female-specific phenotypes in squamates is typically controlled by either temperature-dependent sex determination (TSD) or chromosome-based genetic sex determination (GSD). However, while sex determination is a major switch in individual phenotypic development, it is unknownhow evolutionary transitions between GSD and TSD might impact on the evolution of squamate phenotypes, particularly the fast-evolving and diverse genitalia. Here, we take the unique opportunity of studying the impact of both sex determination mechanisms on the embryological development of the central bearded dragon (Pogona vitticeps). This is possible because of the transitional sex determination system of this species, in which genetically male individuals reverse sex at high incubation temperatures. This can trigger the evolutionary transition of GSD to TSD in a single generation, making P. vitticeps an ideal model organism for comparing the effects of both sex determination processes in the same species.ResultsWe conducted four incubation experiments on 265 P. vitticeps eggs, covering two temperature regimes (“normal” at 28 °C and “sex reversing” at 36 °C) and the two maternal sexual genotypes (concordant ZW females or sex-reversed ZZ females). From this, we provide the first detailed staging system for the species, with a focus on genital and limb development. This was augmented by a new sex chromosome identification methodology for P. vitticeps that is non-destructive to the embryo. We found a strong correlation between embryo age and embryo stage. Aside from faster growth in 36 °C treatments, body and external genital development was entirely unperturbed by temperature, sex reversal or maternal sexual genotype. Unexpectedly, all females developed hemipenes (the genital phenotype of adult male P. vitticeps), which regress close to hatching.ConclusionsThe tight correlation between embryo age and embryo stage allows the precise targeting of specific developmental periods in the emerging field of molecular research on P. vitticeps. The stability of genital development in all treatments suggests that the two sex-determining mechanisms have little impact on genital evolution, despite their known role in triggering genital development. Hemipenis retention in developing female P. vitticeps, together with frequent occurrences of hemipenis-like structures during development in other squamate species, raises the possibility of a bias towards hemipenis formation in the ancestral developmental programme for squamate genitalia.Electronic supplementary materialThe online version of this article (10.1186/s13227-017-0087-5) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Sex determination mode does not affect body or genital development of the central bearded dragon (Pogona vitticeps)

Whiteley

Holleley

Ruscoe

et al. 2017

EvoDevo

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“…Some species show superior abilities to adapt to temperature changes, while others are adversely affected. For example, it has been shown that in an endangered turtle (Podocnemis lewyana), environmental sex determination (a form of phenotypic plasticity) is sensitive to temperature stability during the egg incubation period (Gómez-Saldarriaga et al, 2016). Another study demonstrated that declining species of springtails were more sensitive to desiccation under warmer temperatures as compared to invasive springtails (Chown et al, 2007).…”

Section: Acclimatizationmentioning

confidence: 99%

A Potential Role for Phenotypic Plasticity in Invasions and Declines of Social Insects

2019

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“…While the presence of TSD in M. reevesii is well documented [Du et al, 2007], no study has determined the TSP for this turtle. Thus, we assumed that the target stages sampled here may encompass the early, middle, and late TSP in this species as it occurs in other cryptodiran turtles [Bull and Vogt, 1981], but we note that because the TSP can vary among closely related species [Bull and Vogt, 1981;Bieser and Wibbels, 2014;Gomez-Saldarriaga et al, 2016], further testing is needed to corroborate the validity of this assumption.…”

Section: Tissue Collectionmentioning

confidence: 99%

Effects of Incubation Temperature on the Expression of Sex-Related Genes in the Chinese Pond Turtle, Mauremys reevesii

Tang

Mu²,

Valenzuela³

et al. 2017

Sex Dev

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Despite widespread temperature-dependent sex determination (TSD) in reptiles, it is still unclear how the molecular network responds to temperature variation and drives the sexual fate. Profiling of sex-related genes is the first step in understanding the sex determination system in reptiles. In this study, we cloned the full-length coding sequences of Cyp19a1, Foxl2, Rspo1, Sf1, and Sox9 in an Asian freshwater turtle (Mauremys reevesii) with TSD and identified the expression patterns of these genes and Dmrt1 at different incubation temperatures to understand their roles in urogenital development. Our results showed that Cyp19a1, Foxl2, and Rspo1 were expressed in the adrenal-kidney-gonadal complex at a high level in females, while Sf1 and Dmrt1 were highly expressed in males. In addition, Foxl2 and Rspo1 showed sex-dimorphic expression in the presumed early thermosensitive period (TSP), Dmrt1 was upregulated at the beginning of the presumed TSP, and Sox9 did not show sex-dimorphic expression until the end of the presumed TSP. These results suggest that Foxl2 and Rspo1 are probably upstream genes involved in female sex determination and that Dmrt1 may be a key factor in male sex determination. Therefore, our study provides a solid foundation for further investigations on the molecular mechanism underlying sex determination in M. reevesii.

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Effects of Incubation Temperature on Sex Determination in the Endangered Magdalena River Turtle,Podocnemis lewyana

Cited by 19 publications

References 40 publications

Sex determination mode does not affect body or genital development of the central bearded dragon (Pogona vitticeps)

Sex determination mode does not affect body or genital development of the central bearded dragon (Pogona vitticeps)

A Potential Role for Phenotypic Plasticity in Invasions and Declines of Social Insects

Effects of Incubation Temperature on the Expression of Sex-Related Genes in the Chinese Pond Turtle, <b><i>Mauremys reevesii</i></b>

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