Climate Change and Sex Reversal in Amphibians

Why in News?

Rising global temperatures are raising concerns about the increasing frequency of sex reversal in amphibians and other animals. Scientists are examining whether climate-driven changes in sex development, combined with infectious diseases such as ranavirus, could further threaten amphibian populations. Around 40% of amphibian species are at risk of extinction, making them the most threatened group of vertebrates.

About Sex Reversal

Sex reversal is a biological phenomenon in which an individual’s developed or functional sex differs from the sex expected from its genetic makeup. It occurs naturally in several animal groups, including fish, reptiles and amphibians.

• Fish: Some species can change sex during their lifetime, sometimes more than once.
• Reptiles: Environmental conditions, particularly temperature during embryonic development in certain species, can influence sex determination.
• Amphibians: Some frogs can develop a functional sex that differs from their genetic sex, and certain individuals can become fertile members of the opposite sex.
• Birds: Sex reversal has also been documented in some birds, although it is relatively uncommon.

How Climate Change Can Influence Sex Reversal

• Temperature-sensitive development: In species whose sex determination is influenced by temperature, changing environmental conditions can alter the sex ratio of offspring.
• Disruption of hormonal processes: Temperature and environmental stressors may affect the endocrine pathways involved in sexual development in some species.
• Population imbalance: Changes in the proportion of males and females can affect mating opportunities and reproductive success.
• Long-term survival: Persistent changes in sex ratios may reduce population growth and genetic diversity, particularly in small or threatened populations.

The effects vary across species. Warming does not cause sex reversal in every animal, and the extent to which climate change increases its frequency remains an area of scientific investigation.

Ranavirus and Amphibian Decline

Ranaviruses are pathogens that infect cold-blooded vertebrates, including amphibians, fish and reptiles. They are associated with severe disease outbreaks and mass mortality in some amphibian populations. Certain outbreaks have killed more than 90% of tadpoles in a single event.

Source; The Hindu

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