Final answer:
Leopards are adept climbers, but lions and tigers can climb to a lesser extent, and this ability decreases as they grow larger. Cheetahs, in contrast, have developed for speed on the ground, not for climbing. The climber traits of big cats vary based on their ecological roles and physical characteristics.
Step-by-step explanation:
The question of whether lions, tigers, and cheetahs have begun to lose or not yet fully gained tree climbing traits pertains to animal behavior and evolution, areas within biology. Generally, among these big cats, leopards are known for their climbing abilities, often hauling prey into trees to avoid scavengers. On the other hand, lions and tigers can climb, but they are not as adept due to their larger size and different ecological roles. Cheetahs, being the lightest and designed for speed, have a body structure that is not ideal for climbing, and thus they rarely climb trees. Instead, their morphological traits favor running and acceleration.
Lions and tigers have retained some climbing ability, particularly when they are younger and lighter. However, as they grow, their size and weight generally limit their agility in trees. Cheetahs, however, have never been specialized for climbing. The evolutionary pressures for cheetahs have always favored speed on the ground, not climbing in trees, which is reflected in their physical structure and behavior.