TOEFLスピーキング Task 3

The concept of 'environmental plasticity' refers to the ability of an organism to change its behavior or physiology in response to changes in its environment, without any genetic change. This allows organisms to adapt quickly to short-term environmental fluctuations, enhancing their survival. Plasticity is often triggered by specific environmental cues, such as temperature, light, or food availability, and can be reversible if conditions return to normal. This concept is important in understanding how species cope with changing habitats, especially in the face of human-induced environmental changes.

Professor: So, let me give you a classic example of environmental plasticity. Consider the desert beetle, which lives in extremely hot and dry conditions. On a typical day, the ground temperature can reach 50 degrees Celsius. But the beetle has a clever trick. When it gets too hot, it climbs up a plant stem, sometimes several centimeters above the ground. Because the air temperature at that height is cooler, maybe 35 degrees. This behavior is not learned or genetic; it's an immediate response to the heat. The beetle's body also changes its orientation—it aligns its body with the sun to minimize exposure, and it lifts its abdomen to increase air circulation. These behaviors allow it to survive until the cooler evening. If the temperature drops unexpectedly, the beetle returns to the ground and forages normally. So you see, these are not permanent changes, but flexible adjustments based on the environment.