There has been a growing concern among wildlife scientists and ecologists as far as the effect of global warming on the sex ratio of certain animals is concerned. Rising global temperature has been reported to skew sex ratio in certain species. As the temperature of an ecosystem plays a vital role in the way some animals mate and reproduce, a possible decline in the population and species extinction, in the worst case, are expected because an imbalance in the number of males and females could ultimately suppress the process of reproduction. While in most species, sex of the embryo is determined when fertilisation takes place, in case of animals like sea turtles, alligators, and crocodiles, the gender of the offspring is decided after fertilisation which depends on the temperature of the developing eggs. This phenomenon is called temperature-dependent sex determination (TDS).
Sea turtles have been around for more than 200-million years now. Almost all the species of sea turtles have been affected by the changing climate. The rising temperature of sand has been creating a bias toward female sea turtles. Temperature below 83°Fahrenheit is said to produce more male offspring while a warmer temperature, somewhere above 85° Fahrenheit, produces majorly a female population. A temperature fluctuating between the two extremes produces a mix population of male and female offsprings. Increasing temperature has led the female sea turtles to outnumber the male ones. In Cape Verde, a West African island nation, which has the third-largest nesting population of the loggerhead species of sea turtles, 84 per cent of the hatchlings are females, as per a report published by scientists at University of Exeter, Britain. Fortunately, as a female turtle is able to store sperms for a longer period, a male turtle may not be required for reproduction; however, in the long run, a further rise in temperature would mean more female and lesser male population, which in turn would drastically affect their reproduction.
Unlike female sea turtles’ population which is favoured by warmer temperature, rising temperature is more conducive to more male alligator population. A study done on American alligators has found that if the temperature during the incubation of the eggs is greater than 34°C, the number of male alligators have been reported to be more. This could certainly lead to a male bias in the alligator population if the temperature continues to soar. An excess of males and lesser females could be disastrous for the species which, eventually, will put it at a greater risk of extinction caused by global warming.
The climate change consequences would be harsher for those animals whose sex is determined by variation in temperature. Animals like sea turtles, though, enjoy more attention from the scientific research community, we do not know for sure how many more such species are at risk. Unless we take radical steps to curb greenhouse gases emission by eliminating fossil fuel usage, switching to cleaner energy alternatives, pushing for a circular economy, incorporating sustainable ways to produce our food, controlling human population especially in the major developing countries, we might see a significant loss in habitat and biodiversity in near future.
