Possible Clues:

• Hierarchical system ... or what is formed when the answers to the starred clues are placed end to end
• One is expected to swallow it to replace China in the natural order of things
• Ecological diet hierarchy
• Hawk -> snake -> frog -> insect, e.g
• Ecological diet sequence, or what you can form by linking the starred answers together?
• Ecological hierarchy, and a structure found in this puzzle
• Ecological succession