Climate-driven frog sex reversal threatens species survival, study shows

UPDATE - follow-up to Global warming is turning frogs' sex reversal into an extinction risk: Heat-driven sex reversal in wild agile frogs significantly reduces their reproductive success and leaves their offspring vulnerable to disease and high temperatures, according to a study published in Science Advances on September 3.

Findings in Hungary

Researchers in Hungary studied agile frogs, where excessive heat during the tadpole stage can override chromosomes and turn genetic females into fertile males. While sex-reversed males made up roughly 20% of wild populations, they accounted for only 4% of egg clutches in breeding ponds. Veronika Bokony, lead author and researcher at the HUN-REN Centre for Agricultural Research, noted that when frogs mate freely, sex-reversed individuals struggle to become sires because females often withhold eggs or seek other mates. Offspring of sex-reversed males also showed a 61% rate of sex reversal compared to just 17% for offspring of normal males.

Disease and Extinction Risks

When exposed to an artificial heat wave and the pathogen ranavirus, tadpoles of sex-reversed males carried higher viral loads. University of Canberra professor Arthur Georges praised the field assessment. Computer models showed that combined pressures from lower paternity, high sex reversal rates in offspring, and disease susceptibility could drive small populations to extinction within 60 to 70 years, with ranavirus accelerating population decline by about 10 years.

Context

Amphibians are among the most threatened vertebrates globally, with roughly 40% facing extinction risks due to habitat loss and climate shifts. Understanding how physiological traits respond to rising global temperatures helps scientists forecast biodiversity losses in freshwater ecosystems.