Visual Species Recognition and Mate Choice in Fur Seals: An Experimental Study

Abstract

Most extant fur seal species have discrete breeding ranges, and it is assumed that prior to sealing they were even more separate. However, post sealing most populations have made dramatic recoveries and in the process of so doing have recolonized their previous ranges and possibly further afield. At three locations, Crozet Is., Macquarie Is. and Marion Is., subantarctic and Antarctic fur seals now breed sympatrically and produce hybrid offspring. Hybridization is rare in mammals with multiple barriers to gene exchange between species. At Îles Crozet hybridization between Antarctic and subantarctic fur seals is significantly less (~3%) than expected if random mating were occurring suggesting that one isolating mechanism may be traits by which females choose conspecific mates. Male subantarctic fur seals have a conspicuous pelage with creamy ventral surface, dark dorsal fur and a prominent sagittal crest, visually very distinct from other fur seals which are uniformly dark in color with no sagittal crest. We tested whether male pelage is a visual cue for species recognition by manipulating eight male subantarctic fur seals to make them resemble Antarctic fur seals and comparing their behavior and mating success with eight control males. Experimental male territories had significantly fewer females than control male territories, suggesting that females may choose conspecifics based on visual cues.