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Key Event Title
Increased, Male Biased Sex Ratio
Key Event Components
|male sex differentiation||population of organisms||increased|
Key Event Overview
AOPs Including This Key Event
|AOP Name||Role of event in AOP||Point of Contact||Author Status||OECD Status|
|Aromatase inhibition leads to male-biased sex ratio via impacts on gonad differentiation||KeyEvent||Brendan Ferreri-Hanberry (send email)||Under Development: Contributions and Comments Welcome|
|AR agonism leading to male-biased sex ratio||KeyEvent||Evgeniia Kazymova (send email)||Under development: Not open for comment. Do not cite|
Key Event Description
Animals that exhibit environmental sex determination (ESD) are often at risk of sex ratios being skewed toward a particular sex depending on the environmental conditions in which organisms are exposed during early developmental stages (Ospina-Alvarez et al., 2008;Stewart et al., 2014). This process is particular to every species with ESD as the conditions necessary for the development of either male or female gonads can vary among taxa. Exposure during the critical period of sex differentiation to environmentalconditions that lead offspring sex determination towards a male gonad differentiation pathway is capable of producing sex ratio alterations. Persistence of such male-producing environmental conditions for prolonged periods of times can result in a male‐biased allocation among structured habitats for a given population (Brown et al., 2015).
How It Is Measured or Detected
Domain of Applicability
This key event is applicable to most non-mammalian vertebrates that exhibit environmental sex determination as their primary form of sex determination. Vertebrates with genetic sex determination as their primary form of sex determination but that often times exhibit sexual plasticity towards environmental conditions in their early sex determination stages resulting in a phenotypic sex different from the chromosomal and genetic make-up can be included in this key event.
Brown, A. R., Owen, S. F., Peters, J., Zhang, Y., Soffker, M., Paull, G. C., Hosken, D. J., Wahab, M. A., & Tyler, C. R. (2015). Climate change and pollution speed declines in zebrafish populations. Proceedings of the National Academy of Sciences of the United States of America, 112(11), E1237–E1246.
Canesini, G.; Ramos, J.G.; Muñoz de Toro, Monica, M.(2018) Determinación sexual y diferenciación gonadal en Yacaré overo. Genes involucrados en su regulación y efecto de la exposición a perturbadores endocrinos. (Unpublished Doctoral Thesis). Universidad Nacional Del Litoral
Ospina-Alvarez, N., & Piferrer, F. (2008). Temperature-dependent sex determination in fish revisited: prevalence, a single sex ratio response pattern, and possible effects of climate change. PloS one, 3(7), e2837.
Stewart, K. R., & Dutton, P. H. (2014). Breeding sex ratios in adult leatherback turtles (Dermochelys coriacea) may compensate for female-biased hatchling sex ratios. PloS one, 9(2), e88138. https://doi.org/10.1371/journal.pone.0088138