Final answer:
Elman Service's anthropological studies identified pastoralism and horticulture as the two subsistence systems most associated with tribal political organization, as they depend on extended family structures for managing resources.
Step-by-step explanation:
The two subsistence systems more strongly associated with tribal political organization are pastoralism and horticulture. Within anthropological studies, these particular modes of subsistence are considered central to tribal societies because they involve extended families controlling important resources such as animals and land, which is typical of tribal social organization. Anthropologist Elman Service's characterization of social organization highlighted these relationships, positing that tribal societies are often larger than bands and are organized around extended family structures and/or councils that manage leadership, decision-making, and conflict resolution. Pastoralism involves the raising and managing of herd animals, which often allows for wealth accumulation, and is distinguished by the mobility of pastoral groups. Horticulture, on the other hand, involves slash-and-burn farming or other forms of small-scale cultivation which can support settled communities without the use of intensive agricultural techniques like irrigation or plow agriculture, typical for tribal groups.