Final answer:
Direct fitness focuses on an individual's reproductive success, while inclusive fitness takes into account an individual's contribution to the reproductive success of relatives. This can be achieved through cooperative behaviors or by helping relatives survive and reproduce.
Step-by-step explanation:
In biology, direct fitness refers to an individual's reproductive success through producing their own offspring. It focuses on the number of viable offspring an individual can produce and raise to maturity. In contrast, inclusive fitness takes into account an individual's contribution to the reproductive success of their relatives, including siblings or nieces and nephews.
For example, if a bird helps its siblings raise their young and thus increases the survival and reproduction of its relatives, it is increasing its inclusive fitness. Inclusive fitness considers both an individual's direct reproductive success and the success of relatives, which can be achieved through cooperative behaviors or by helping relatives survive and reproduce.