TitleContext-dependent kin discrimination in larvae of the marbled salamander, Ambystoma opacum
Publication TypeJournal Article
Year of Publication1996
AuthorsHokit, DG, Walls, SC, Blaustein, AR
JournalAnimal Behaviour
Type of ArticleJournal Article

The context-dependent nature of kin discrimination was examined in larvae of the marbled salamander, Ambystoma opacum. In a graphical analysis, relationships between aggression and social and ecological factors were explored. Increasing relatedness between individuals was predicted to reduce aggressive encounters, except when correlates of fitness (e.g. body size) differed between individuals and/or when environmental conditions increased the profitability of aggression. These predictions were tested in a multifactorial experiment in which genetic relatedness, food quantity, relative body size and the potential for physical encounters were manipulated. The effects of each factor and their interactions on larval aggression and correlates of fitness (body size and timing of metamorphosis) were examined. Frequency of aggression depended upon an interaction between kinship, food quantity and relative larval size. Thus, in accordance with our graphical model, kinship-based aggression varied in a context-dependent fashion. Low food level reduced body size and increased the time required to reach metamorphosis. When larvae were not separated by a barrier, growth was inhibited in the smaller, but not the larger, individual of a pair. Moreover, the larval period was significantly shortened in chambers where barriers were absent. Neither kinship nor initial relative size, either alone or in combination with the other factors, significantly affected larval performance. These results show that the frequency of larval aggression in A. opacum depends upon prevailing social and environmental conditions; however, the influence of aggression on larval growth and metamorphosis remains unclear. Previous inferences regarding context-dependent kin discrimination in amphibians have been based on independent, interspecific studies or concurrent, intraspecific comparisons between individuals of alternative morphologies. The present results provide direct evidence that simultaneous variation in multiple socio-ecological factors may alter aggression in a single amphibian species in which kin discrimination is known to occur. (C) 1996 The Association for the Study of Animal Behaviour.

URL<Go to ISI>://WOS:A1996VA49700003