Abstract
1. In many social species, reproductive success varies between
individuals within a population, resulting in socially structured
populations. Social network analyses of familial relationships may
provide insights on how fitness influences population-level demographic
patterns. These methods have however rarely been applied to
genetically-derived pedigree data from wild populations. 2. Here we use
social networks to reconstruct parent-offspring relationships and create
a familial network from polygamous boreal woodland caribou (Rangifer
tarandus caribou) in Saskatchewan, Canada, to inform recovery efforts.
We collected samples from 933 individuals at 15 variable microsatellite
loci along with caribou-specific primers for sex identification. Using
social network metrics, we assess the contribution of individual caribou
to the population with several centrality metrics and then determine
which metrics are best suited to inform on the population demographic
structure. We look at the centrality of individuals from eighteen
different local areas, along with the entire population. 3. We found
substantial differences in centrality of individuals in different local
areas, that in turn contributed differently to the full network,
highlighting the importance of analyzing social networks at different
scales. The full network revealed that boreal caribou in Saskatchewan
form a complex, interconnected social network with strong familial ties,
as the removal of edges with high betweenness did not result in distinct
subgroups. Alpha, betweenness, and eccentricity centrality were the most
informative metrics to characterize the population demographic structure
and for spatially identifying areas of highest fitness levels and social
cohesion across the range. 4. Synthesis and applications: Our results
demonstrate the value of different network metrics in assessing
genetically-derived familial networks. The spatial application of the
familial networks identified areas of higher fitness levels and social
cohesion across the range in support of population monitoring and
recovery efforts.