Final answer:
Robust traits serve an adaptive function by providing individuals with advantages that help them survive and reproduce.
Step-by-step explanation:
Robust traits serve an adaptive function by providing individuals with advantages that help them survive and reproduce. These traits give individuals an advantage over others, increasing their chances of having more offspring. So, robust traits are genetically based adaptations that have evolved because they aid in an organism's survival and reproduction in a given environment. For example, flies that trade early reproductive energy for greater storage of energy in their bodies are favored by natural selection because they are better able to survive the cold.