Network analysis provides a powerful tool to analyze complex influences of social and ecological structures on community and household dynamics. Most network studies of social-ecological systems use simple, undirected, unweighted networks. We analyze multiplex, directed, and weighted networks of subsistence food flows collected in three small indigenous communities in Arctic Alaska potentially facing substantial economic and ecological changes. Our analysis of plausible future scenarios suggests that changes to social relations and key households have greater effects on community robustness than changes to specific wild food resources.multiplex networks | food sharing | mixed subsistence-cash economies | climate change | social-ecological systems G lobally, while millions of people combine subsistenceand market-based activities for their livelihoods, they are increasingly exposed to substantial perturbations from both climate change and globalization (1-4). Mixed subsistence-cash economies are characterized by strong human-landscape connections, in which social relations facilitate flows of food and other resources among households (5). Early termed the moral economy (6), cultural norms of sharing and cooperation enable risk sharing, improve food security, improve health and equity outcomes, and contribute to group identity and cohesion (7-10). Embedded social relations have been termed the "capital of the poor" (11) as they allow flexible access to resources in times of stress and rapid change (12-16). Yet inequities can emerge as cooperative institutions are stressed (17, 18) and effects of specific exposures on people, social relations, and landscapes are uncertain (3,4,19).The indigenous Alaskan communities considered here represent two ethno-linguistic groups occupying distinct ecological zones with differential access to marine and terrestrial resources: coastal Iñupiat and interior Athabascan Gwich'in (SI Appendix, Fig. 1). Common to all three communities are (i) exposure to significant ecological and economic change, (ii) substantial reliance on subsistence production of local wild foods, (iii) engagement in the market economy, and (iv) a strong focus on social relations. Within communities, households are characterized by strong heterogeneity in roles and degree of subsistence engagement (20,21). Although many challenges face Arctic communities (22, 23), we focus on three frequently cited scenarios: changes in resource abundance or distribution due to climate, shifts in cultural practices related to sharing and cooperation, and loss of key productive households. Specifically, climate change could affect access to critical species or entire species groups. Engagement in the cash economy and high food and fuel costs could displace dependence on social relations (2). Sharing and contributions have been described as particularly vulnerable to these changes (24, 25). Finally, loss of highly productive key households-it is well documented in Alaska that 30% of rural households produce 70% of food and redistri...