Understanding Sex Determination by Temperature

Temperature-dependent sex determination (TSD) is a biological process where the incubation temperature of eggs influences the sex of the developing offspring. This phenomenon is observed in various animal groups.

Identifying Organisms with TSD

Let's examine the provided options:

• Some reptiles: This group famously includes species like turtles, crocodiles, and many lizards, where specific incubation temperature ranges produce males, while others produce females.
• All birds: Sex determination in birds is primarily governed by sex chromosomes (Z and W chromosomes), not environmental temperature.
• Humans: Human sex is determined by sex chromosomes (XX for females, XY for males) and is not influenced by temperature.
• All fish: While TSD occurs in a few fish species, it is not a universal trait across all fish; many rely on genetic or chromosomal factors.

Conclusion on TSD

Based on biological principles, some reptiles are the group where environmental temperature plays a crucial role in determining the sex of the individuals.