Skin coloration as a possible non-invasive marker for skewed sex ratios and gonadal abnormalities in immature common toads (Bufo bufo)

Újhegyi, Nikolett; Bókony, Veronika

doi:10.1016/j.ecolind.2020.106175

Cited by 12 publications

(6 citation statements)

References 64 publications

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“…The solvent‐control group, in which the rearing water contained 1 µl L −1 ethanol, served as control for the EE2 treatments, in which the nominal concentration was either 1 ng L −1 or 1 µg L −1 EE2, obtained by dissolving EE2 powder (Sigma E4876) in 96% ethanol and adding 1 µl of this solution to each litre of rearing water. Actual EDC concentrations were close to the nominal concentrations (Ujhegyi & Bókony, 2020). Both EDCs are documented to occur in our actual study ponds (Bókony et al, 2018).…”

Section: Methodssupporting

confidence: 65%

“…We detected no sex reversal in any of the treatment groups, except for the higher concentration of EE2 (Figure 2). However, detection of sex reversal might have been hindered by the high mortality rate in the treatment group of high concentration of the glyphosate‐based herbicide (see more details in Ujhegyi & Bókony, 2020). In the high‐concentration EE2 treatment, all genetic males developed into phenotypic females, regardless of their original habitat type (Figure 2).…”

Section: Resultsmentioning

confidence: 99%

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Novel genetic sex markers reveal unexpected lack of, and similar susceptibility to, sex reversal in free‐living common toads in both natural and anthropogenic habitats

et al. 2022

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Anthropogenic environmental changes are affecting biodiversity and microevolution worldwide. Ectothermic vertebrates are especially vulnerable because environmental changes can disrupt their sexual development and cause sex reversal, a mismatch between genetic and phenotypic sex. This can potentially lead to sex‐ratio distortion and population decline. Despite these implications, there is scarce empirical knowledge on the incidence of sex reversal in nature. Populations in anthropogenic environments may be exposed to sex‐reversing stimuli more frequently, which may lead to higher sex‐reversal rate or, alternatively, these populations may adapt to resist sex reversal. We developed PCR‐based genetic sex markers for the common toad (Bufo bufo) to assess the prevalence of sex reversal in wild populations living in natural, agricultural and urban habitats, and the susceptibility of the same populations to two ubiquitous oestrogenic pollutants in a common garden experiment. We found negligible sex‐reversal frequency in free‐living adults despite the presence of various endocrine‐disrupting pollutants in their breeding ponds. Individuals from different habitat types showed similar susceptibility to sex reversal in the laboratory: all genetic males developed female phenotype when exposed to 1 µg L−1 17α‐ethinylestradiol (EE2) during larval development, whereas no sex reversal occurred in response to 1 ng L−1 EE2 and a glyphosate‐based herbicide with 3 µg L−1 or 3 mg L−1 glyphosate. The latter results do not support that populations in anthropogenic habitats would have either increased propensity for or higher tolerance to chemically induced sex reversal. Thus, the extremely low sex‐reversal frequency in wild toads compared to other ectothermic vertebrates studied before might indicate idiosyncratic, potentially species‐specific resistance to sex reversal.

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Section: Methodssupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Novel genetic sex markers reveal unexpected lack of, and similar susceptibility to, sex reversal in free‐living common toads in both natural and anthropogenic habitats

et al. 2022

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“…Also, the rates of development and growth until metamorphosis can have life-long effects on fitness in amphibians (Smith, 1987;Berven, 1990;Altwegg and Reyer, 2003). However, sex differences in larvae are very rarely investigated due to the difficulties of phenotypic sex identification in immature animals (Ujhegyi and Bókony, 2020) and genetic sexing in amphibians overall (Nemesházi et al, 2020). In the agile frog, males typically start reproducing 1 year earlier than females (Riis, 1991;Sarasola-Puente et al, 2011), and larger males are more successful in male-male competition (Vági and Hettyey, 2016).…”

Section: Introductionmentioning

confidence: 99%

Sex Reversal and Performance in Fitness-Related Traits During Early Life in Agile Frogs

et al. 2021

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Sex reversal is a mismatch between genetic sex (sex chromosomes) and phenotypic sex (reproductive organs and secondary sexual traits). It can be induced in various ectothermic vertebrates by environmental perturbations, such as extreme temperatures or chemical pollution, experienced during embryonic or larval development. Theoretical studies and recent empirical evidence suggest that sex reversal may be widespread in nature and may impact individual fitness and population dynamics. So far, however, little is known about the performance of sex-reversed individuals in fitness-related traits compared to conspecifics whose phenotypic sex is concordant with their genetic sex. Using a novel molecular marker set for diagnosing genetic sex in agile frogs (Rana dalmatina), we investigated fitness-related traits in larvae and juveniles that underwent spontaneous female-to-male sex reversal in the laboratory. We found only a few differences in early life growth, development, and larval behavior between sex-reversed and sex-concordant individuals, and altogether these differences did not clearly support either higher or lower fitness prospects for sex-reversed individuals. Putting these results together with earlier findings suggesting that sex reversal triggered by heat stress may be associated with low fitness in agile frogs, we propose the hypothesis that the fitness consequences of sex reversal may depend on its etiology.

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“…On the other hand, pesticides can also directly act on the hormonal pathways of developmental processes as endocrine disrupting chemicals (EDCs), which alter the normal functioning of the endocrine system leading to impaired reproduction mechanisms such as infertility or intersex (Ujhegyi and Bókony 2020). EDCs have been found in amphibian breeding sites in agricultural landscapes.…”

Section: Introductionmentioning

confidence: 99%

Pesticide exposure affects reproductive capacity of common toads (Bufo bufo) in a viticultural landscape

2021

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Amphibian populations are declining worldwide at alarming rates. Among the large variety of contributing stressors, chemical pollutants like pesticides have been identified as a major factor for this decline. Besides direct effects on aquatic and terrestrial amphibian stages, sublethal effects like impairments in reproduction can affect a population. Therefore, we investigated the reproductive capacity of common toads (Bufo bufo) in the pesticide-intensive viticultural landscape of Palatinate in Southwest Germany along a pesticide gradient. In a semi-field study, we captured reproductively active common toad pairs of five breeding ponds with different pesticide contamination level and kept them in a net cage until spawning. Toads from more contaminated ponds showed an increased fecundity (more eggs) but decreased fertilization rates (fewer hatching tadpoles) as well as lower survival rates and reduced size in Gosner stage 25, suggesting that the higher exposed populations suffer from long-term reproductive impairments. In combination with acute toxicity effects, the detected sublethal effects, which are mostly not addressed in the ecological risk assessment of pesticides, pose a serious threat on amphibian populations in agricultural landscapes.

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Skin coloration as a possible non-invasive marker for skewed sex ratios and gonadal abnormalities in immature common toads (Bufo bufo)

Abstract: Skin coloration as a possible non-invasive marker for skewed sex ratios and gonadal abnormalities in immature common toads (Bufo bufo

Cited by 12 publications

References 64 publications

Novel genetic sex markers reveal unexpected lack of, and similar susceptibility to, sex reversal in free‐living common toads in both natural and anthropogenic habitats

Novel genetic sex markers reveal unexpected lack of, and similar susceptibility to, sex reversal in free‐living common toads in both natural and anthropogenic habitats

Sex Reversal and Performance in Fitness-Related Traits During Early Life in Agile Frogs

Pesticide exposure affects reproductive capacity of common toads (Bufo bufo) in a viticultural landscape

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