Here are the terms matched with their corresponding descriptions:
- Mexico - 8. one of the only 17 countries recognized as Mega diverse
- Great Lakes - 3. nearly 20% of the world's fresh surface water is here
- Rio Grande - 5. stretches of it act as a natural border between the US and Mexico
- Cascade Range - 7. location of Mount St. Helens
- Nearctic - 6. North America and Canada make up the ecoregion
- Isthmus of Panama - 1. narrow curves with land that connects North and South America
- Guatemala - 2. an endemic species inhabited Sierra Gorda
- Lake Erie - 9. this body of water is a natural border between the US and Canada
- Endangered species in Sierra Gorda - 4. an endangered species found in Sierra Gorda
(Note: Depending on the context, number 2 might also refer to a specific species; however, I matched it to the only description in your list.)