Final answer:
High altitudes can cause acute mountain sickness in low-altitude natives. Acclimatization and long-term adaptations can also occur to improve oxygen levels.
Step-by-step explanation:
High altitudes can have immediate, intermediate, and long-term effects on low-altitude natives. Immediate effects include a condition called acute mountain sickness (AMS) which can cause symptoms like headaches, disorientation, fatigue, nausea, and lightheadedness. Intermediate effects include the body's process of acclimatization to high altitude, which involves adjustments in oxygen levels and the production of more hemoglobin. Long-term effects can vary depending on the individual, but may include enhanced respiratory function and cardiovascular adaptations.