Sage-Grouse exhibit lekking behavior where males congregate on communal display grounds (leks) and females select a mate, breed, and then incubate eggs and raise young on their own (Wiley 1973). Many hypotheses have been proposed to explain why males participate in leks when the majority of males apparently fail to mate. Explanations range from anticipating future breeding opportunities (Wiley 1973), unpredictable female copying behavior (Kokko 1997), reduced predation risk (Boyko et al. 2004), parasite-host co-evolution (Boyce 1990), increased mating opportunity (Höglund and Alatalo 1995) to kin selection (Kokko and Lindström 1996), with the latter hypothesis having been tested on lekking grouse species using genetic data (Höglund et al. 1999, Bouzat and Johnson 2004, Gibson et al. 2005, Lebigre et al. 2007, Segelbacher et al. 2007). Kin selection is thought to drive the participation of low-ranking males in leks because they may indirectly and directly increase their own fitness by joining male relatives (Kokko and Lindström 1996, Sherman 1999). Subordinate males may benefit indirectly if their presence at the lek increases the reproductive success of related males. Direct benefits to subordinate males include increased mating opportunities with increased lek size, increased number of females attending the lek, or attraction of females to the lek that might be interested in males other than dominant individuals (Kokko and Lindström 1996, Sherman 1999, Sœther 2002). Several genetic studies have found evidence for kin association on leks (Höglund et al. 1999, Petrie et al. 1999, Bouzat and Johnson 2004), but others have not (McDonald and Potts 1994, Martín et al. 2002, Madden et al. 2004, Höglund and Shorey 2003, DuVal 2007, Loiselle et al. 2007, Segelbacher et al. 2007, Knopp et al. 2008) including the only study on Sage-Grouse (Gibson et al. 2005).
We used polymorphic microsatellites to answer two main questions. First, what is the genetic diversity and connectivity of Sage-Grouse in Alberta? Second, are leks composed of related males? We expected to find low diversity and high differentiation between leks because of low estimated population size and extensive habitat fragmentation across the species’ range in Alberta. For within-lek relatedness, we predicted low levels of male kinship within leks because a study of Sage-Grouse in California found males were typically unrelated (Gibson et al. 2005) and there is no evidence to suggest Sage-Grouse in Alberta would show different patterns of lek organization.