Yunnan is located at the junction of two major biodiversity hotspots in the world. The high-altitude Qinghai-Tibet Plateau quickly transitioned to the low-altitude Malay Peninsula in Yunnan. Most rivers in Yunnan are north-south, and tropical flora and fauna follow the north-west wet and hot The air has penetrated into most areas of Yunnan. Therefore, Yunnan has more than 50% of plant species, more than 70% of animal species, and more than 80% of vegetation types in 4% of the country's land area. What does this passage mean? ['The characteristics of biodiversity in Yunnan are outstanding.', 'Yunnan has special natural geographical conditions.', 'The relationship between topography and biodiversity in Yunnan.', 'Links between climate and biodiversity in Yunnan.']