Alpha-male paternity in elephant seals

The aim of this study was to assess paternity of males that dominated matin g in harems at northern (Mirounga angustirostris) and southern (M. leonina) elephant seal rookeries using DNA fingerprinting and microsatellite DNA an alysis. Southern alpha males had greater reproductive success than most nor thern alphas at similar-sized harems. Comparison of the relatedness between pups within harems also suggested that fewer males achieved matings in the southern elephant seal population. This was consistent with behavioral obs ervations that suggest greater competition for mates in northern elephant s eal harems. Reproductive success was consistent with estimates of mating su ccess in some cases, but lower than expected for some northern elephant sea l alpha males. A lower reproductive success than predicted from mating beha vior may arise from a variety of factors including sperm competition, male sperm depletion from Frequent mating, or reduced fertility. The alternative s are discussed in the context of environmental and historical factors.