Final answer:
If group selection is an evolutionarily stable strategy, then the traits conferring (d) advantages to the group must be heritable. These heritable traits can result in altruistic behaviors that enhance the group's fitness and are selected for by natural selection, provided they contribute to the genetic success of the group.
Step-by-step explanation:
If group selection—the differential survival and reproduction of groups—is an evolutionarily stable strategy, then the characteristics of the group must be heritable. This means that the traits that confer a survival and reproductive advantage to the group must be passed down through generations. Such heritable traits are necessary for a group to be fit in evolutionary terms.
Natural selection acts on populations by selecting individuals with favorable traits for survival. Group selection is an extension of this principle, where the differential survival and reproduction of groups may favor the spread of altruistic behaviors, if those behaviors enhance the group's fitness and are heritable. This aspect of evolutionary biology is relevant in understanding how certain cooperative traits can become prevalent in a species.
Another important point is that for a behavior to be acted upon by selection, it must be heritable. This is because natural selection can only increase or decrease the frequency of genes that are passed from one generation to the next—not on behaviors that cannot be inherited. Therefore, for a group to exhibit stable altruistic traits, those traits must have a genetic basis.
Moreover, while group selection often implies the cooperative behavior among related individuals due to shared genes, it can also occur among unrelated members if the group's collective behavior improves its overall chances of survival and reproduction. However, it is important to distinguish between behaviors that are truly altruistic and those that may appear altruistic but ultimately provide some benefit to the individual exhibiting them.