How does temperature affect sex determination in some reptiles?

In some reptiles, the temperature during embryonic development determines the sex of the offspring.

Temperature-dependent sex determination (TSD) is a type of environmental sex determination that is quite common in reptiles. This means that the sex of the offspring is not determined by the genetic information received from the parents, but by the temperature at which the eggs are incubated during a critical period of embryonic development.

The exact mechanism of how temperature influences sex determination is not fully understood, but it is believed to involve enzymes that are sensitive to temperature. These enzymes control the production of sex hormones, which in turn influence the development of the sex organs. At certain temperatures, these enzymes may favour the production of male hormones, leading to the development of male offspring, while at other temperatures, they may favour the production of female hormones, leading to the development of female offspring.

The temperature range within which sex determination occurs is known as the pivotal temperature. For example, in many turtle species, eggs incubated at temperatures below the pivotal temperature will develop into males, while those incubated at temperatures above the pivotal temperature will develop into females. However, the pivotal temperature and the pattern of sex determination can vary greatly among different species.

This phenomenon has important implications for the survival of these species in the face of climate change. As global temperatures rise, there is a risk that populations could become heavily skewed towards one sex, threatening the survival of the species. For example, a recent study found that more than 99% of green sea turtles in some areas of the Great Barrier Reef are now female due to rising temperatures.

In conclusion, temperature-dependent sex determination is a fascinating and complex process that plays a crucial role in the life cycle of many reptile species. Understanding this process is not only important for our understanding of reptile biology, but also for our ability to protect these species in a rapidly changing world.