What concept explains the increase in overall fitness of a group when some members assist in the survival and reproduction of offspring?

The concept that best explains the increase in overall fitness of a group when some members assist in the survival and reproduction of offspring is inclusive fitness. Inclusive fitness considers not only the direct reproductive success of an individual but also the impact of an individual's actions on the reproduction of their relatives. When individuals help their relatives raise offspring, they can increase the chances of those offspring surviving and reproducing, thereby enhancing the shared genetic contribution to the next generation.

This concept introduces the idea that altruistic behaviors, which may seem disadvantageous to an individual in the short term, can actually lead to a net increase in genetic representation within the population if those being helped share a significant proportion of their genes. Hence, through inclusive fitness, helping behaviors can improve the overall fitness of the group or lineage.

While natural selection relates to the broader processes by which traits increase an organism's chances of survival and reproduction in a given environment, inclusive fitness specifically addresses the genetic contributions of individuals to the fitness of their relatives. Adaptive radiation describes a process of diversification from a common ancestor into new environments, which does not directly explain the assistance in offspring survival. Kinetic selection is not a standard term in evolutionary biology and does not encapsulate these dynamics effectively.