Genetic structure of lions (Panthera leo L.) in the Selous Game Reserve:: implications for the evolution of sociality

We use 14 microsatellites to examine the genetic structure of a lion (Panthera leo L.) population in southern Tanzania. Heterozygosity levels were high (0.75 +/- 0.08). Relatedness estimates showed that prides often had close relatives in neighbouring prides, whereas few relatives were found in prides not sharing a border. The drop-off in relatedness with distance was highly significant. Female pridemates exhibited a higher mean relatedness (0.26 +/- 0.07) to one another than did pride males (0.11 +/- 0.07). Mean relatedness among females was significantly higher in small prides than in large ones. Prides exhibited significant inbreeding avoidance (F-IL: -0.11). Mating did not detectably differ from random across prides (F-IT: -0.02 ns). In addition to being recognizable behavioural and demographic units, prides were statistically distinct genetic units (F-LT : 0.07). Some neighbouring prides grouped together both geographically and genetically, forming 'superprides' in the population (F-ZT = 0.05). Thus, although individual prides were genetically distinct, there was an important genetic structure above the level of social groups.