Some like it dry: Water restriction overrides heterogametic sex determination in two reptiles

• Published in: Ecology and evolution Vol. 9; no. 11; pp. 6524 - 6533
• Main Authors: Dupoué, Andréaz, Lourdais, Olivier, Meylan, Sandrine, Brischoux, François, Angelier, Frédéric, Rozen‐Rechels, David, Marcangeli, Yoan, Decencière, Béatriz, Agostini, Simon, Le Galliard, Jean‐François
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.06.2019; Wiley Open Access; John Wiley and Sons Inc; Wiley
• Subjects: Animal biology; Animal reproduction; Biodiversity and Ecology; Councils; dehydration; early growth; Environmental Sciences; Evolution; Females; Fitness; Gene expression; Gestation; heterogamety; Influence; Life Sciences; Males; Offspring; Original Research; Population; Population stability; Pregnancy; Reproductive Biology; Reproductive fitness; Reptiles; Reptiles & amphibians; Sex; Sex determination; Sex ratio; Sex reversal; Sexes; Sexual reproduction; Snakes; survival; Vertebrate Zoology; Water deprivation; early growth; heterogamety; sex reversal; survival; dehydration; gestation; sex determination; sex ratio
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.5229

The evolution of sex determination is complex and yet crucial in our understanding of population stability. In ectotherms, sex determination involves a variety of mechanisms including genetic determination (GSD), environment determination (ESD), but also interactions between the two via sex reversal. In this study, we investigated whether water deprivation during pregnancy could override GSD in two heterogametic squamate reptiles. We demonstrated that water restriction in early gestation induced a male‐biased secondary sex ratio in both species, which could be explained by water sex reversal as the more likely mechanism. We further monitored some long‐term fitness estimates of offspring, which suggested that water sex determination (WSD) represented a compensatory strategy producing the rarest sex according to Fisher's assumptions of frequency‐dependent selection models. This study provides new insights into sex determination modes and calls for a general investigation of mechanisms behind WSD and to examine the evolutionary implications. OPEN RESEARCH BADGES This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at https://doi.org/10.5061/dryad.mv06pv1. This study demonstrated that water restriction in early gestation induced a male‐biased secondary sex ratio in two reptile species (a snake and a lizard), which could be explained by water sex reversal as the more likely mechanism. We further tested the assumptions of evolutionary models. This study cases of water sex determination (WSD) seemed to help producing the rarest sex according to Fisher's assumptions of frequency‐dependent selection models.