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Female natal philopatry has often been implicated as an important factor in moose ( Alces alces ) home range formation, with many populations showing behavioral evidence of sympatric home ranges among related individuals. However, previous genetic studies have failed to detect genetic subpopulation structure, leading to questions as to whether philopatry is a significant factor contributing to intra- and inter-population genetic structure. Here, we examine calving location data from radiomarked individuals ( n = 110) collected in 2 separate populations in Berners Bay and Gustavus, Alaska, to examine the extent to which genetic structure originating from philopatry is evident at fine spatial scales. When populations were combined, their overall relatedness correlogram was significant ( P < 0.001), with mean r = 0.079 between 0 km and 1.5 km ( P = 0.079). Additionally, 13% of the population shows significantly positive relatedness to their 4 nearest neighbors, with an overall average r = 0.19 of those focal individuals to their neighbors. We suggest that habitat structure, especially linear habitats (i.e., river valleys), or habitat bounded with barriers to dispersal, may be a factor in promoting the development of this structure. This study presents the 1st known evidence for fine-scale social genetic structure in moose and natal philopatry to calving locations in moose. In the context of natal philopatry within cervids, these findings identify several cervid-wide commonalities.

Alaska caribou (Rangifer tarandus granti) in southwestern Alaska are a poorly understood system, with differing descriptions of their regional population structure, population abundance that has varied greatly through time and instances of the release of domestic reindeer (R. t. tarandus) into their range. Here, we use 21 microsatellites and 297 individuals to investigate the genetic population structure of herds and examine for population bottlenecks. Then, using genetic characteristics of existing reindeer populations, we examine introgression into the wild caribou populations. Caribou of the area are genetically diverse (H E between 0.69 and 0.84), with diversity decreasing along the Alaska Peninsula (AP). Using G ST and Jost's D, we find extensive structuring among all herds; Migrate-n finds that AP herds share few effective migrants with other herds, with Southern AP and Unimak Island herds having the least. Bayesian clustering techniques are able to resolve all but Denali and Mulchatna caribou herds. Using a conservative assignment threshold of q reindeer ≥ 0.2, 3% of caribou show signs of domestic introgression. Denali herd has the most introgressed individuals (6.9%); those caribou herds that were historically adjacent to smaller reindeer herds, or were historically without adjacent herding, show no admixture. This domestic introgression persists despite the lack of managed reindeer in the region since the 1940s. Our results suggest that despite previous movement data indicating metapopulation-like dispersal in this region, there may be unknown barriers to reproduction by dispersing individuals. Finally, our results support findings that wild and domestic Rangifer can hybridize and show this introgression may persist dozens of generations after domestics are no longer present.