DISCRIMINATION OF KIN-BASED AND DIET-BASED CUES BY LARVAL SPADEFOOT TOADS, SCAPHIOPUS-INTERMONTANUS (ANURA, PELOBATIDAE), UNDER LABORATORY CONDITIONS

We conducted laboratory choice tests with larval Great Basin spadefoot toads, Scaphiopus intermontanus Cope, to evaluate their ability to di scriminate kin- and diet-based cues. When offered a choice between sti mulus groups composed of familiar siblings and unfamiliar nonsiblings (both stimulus groups, as well as test individuals, raised on the same diet), larvae did not associate preferentially with either stimulus g roup. In diet-based cue experiments, larvae raised on Tubifex worms as sociated preferentially with unfamiliar nonsiblings raised on the same diet over unfamiliar siblings raised on rabbit chow. In the complemen tary experiment, however, larvae raised on rabbit chow did not associa te preferentially with either stimulus group. These results do not sup port a role for kin discrimination and kin selection in S. intermontan us larvae. If discrimination does occur, the results suggest that envi ronmentally derived cues may be the predominant means by which kin are discriminated. Moreover, the different results of the diet-based cue experiments suggest that larvae are not restricted to prefer only cues representative of their natal environment. Although familiarity is in volved, larvae also may be capable of reacting preferentially to a nov el stimulus based on some type of quality assessment.