Salamanders pheromonal functions

The production of a female-influencing secretion from the chin gland of male Plethodontid salamander (P. jordani) points to a similar extension of function by the acquisition of female olfactory sensitivity to an intercellular signal protein. Female receptivity is enhanced by a male cytokine-like compound of the interleukin-6 family, in its released form. Rollman et al. (1999) note that pheromonal activity is a previously unrecognised function for cytokines. 

Delivery styles vary greatly among species of salamanders, yet the only function demonstrated for salamander courtship pheromones has been to increase female receptivity. The change in receptivity is inferred on the basis of reduced courtship time as a result of pheromone delivery. Reduced courtship time has been demonstrated quantitatively for two species of terrestrial plethodontid salamanders. In D. ocoee (the species using an injection mode of delivery), courtship time was shorter when a female was treated with a pheromone extract versus an inactive (saline) control solution (Houck Reagan, 1990). In the plethodontid R jordani, pairs in which the female was pre-treated with courtship pheromones escalated to advanced stages of courtship more quickly on average than did pairs in which the... 

The purpose of this scant review of homing and courtship is to emphasize that salamanders produce a variety of pheromones, probably from a variety of glands, and having a diversity of functions. However, there is not a single case where the composition and origin of a pheromone is well known, a factor that severely inhibits the study of pheromonal communication during territorial defense by salamanders. 

In general, the same techniques are used to collect stimuli for tests of pheromones used in reproduction as for tests of territorial pheromones. It is possible that in many cases the same pheromones may serve both functions advertisement to potential competitors and to potential mates. Although the collection techniques are similar for both types of pheromones, many studies of sexual advertisement pheromones have focused on aquatic animals (primarily newts) and the techniques described above for terrestrial salamanders have been modified for use in aquatic environments. For example, test animals might be exposed to water from a chamber that had contained another salamander (Dawley 1984b) or from sponges soaked with secretions from other salamanders (Twitty 1955). 

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