Red-spotted newt

Park, D. and Propper, C. R. (2001). Repellent function of male pheromones in the red-spotted newt. Journal of Experimental Zoology 289,404—408. 

Responses of male red-spotted newts Notophthalmus viridescens) to waterborne female odors... 

In the case of the red-spotted newt (Notophthalmus viridescens) of North America, the red eft is the stage that occurs after transformation of the aquatic larva. The red eft is bright red or orange, and is a pre-reproductive adult stage. The red eft wanders widely in forests, sometimes for several years, and is most common on moist nights. Eventually, the red eft migrates to an aquatic... 

Not ah populations of red-spotted newts display this type of life cycle, for some coastal populations bypass the terrestrial red eft stage, and produce breeding adults directly from larvae. These adults may retain some larval characteristics, such as gills, which is an example at neoteny, or paedomorphosis. 

The red eft stage of the red-spotted newt contains toxic, bad-tasting chemicals in its skin. As a result, many potential predators learn to avoid this animal, and will not eat red efts. The range of the red salamander Pseudotriton ruber) overlaps part of the larger range of the red-spotted newt in the eastern United States. It appears that the superficially similar but non-toxic red salamander may be a mimic of the color of the red eft, taking advantage of the fact that many predators avoid this animal as food. 

THE PHEROMONAL REPELLING RESPONSE IN RED-SPOTTED NEWTS (NOTOPHTHALMUS... 

Using a series of Y-maze olfiictoiy choice tests, we found that male red-spotted newts show a pheromonal repelling response and that the occurrence of the repelling response depends on the number of males present, on male-female interactions, and on female fecundity. The purpose of the work presented here is to describe and elaborate on the main findings that we have reported in previous studies (Experiment I-IV, Park and Propper, 2001 Experiment V-VI, Park et al., submitted). 

In conclusion, the choice of a specific courting site should be a complex process, because individuals should consider many factors that affect their expected PRR. The details of the process of choosing a potential courting site are poorly understood. The existence of a pheromonal repelling response in red-spotted newts will allow us to investigate the relative importance of the factors involved. In future experiments, we plan to further explore the factors that contribute to the pheromonal repelling response, as well as the nature of the chemical cues involved. Finally, this paradoxical phenomenon, in which a mixture of two different odorants is less attractive than either alone, provides a unique opportunity to examine the processing of pheromones and odorant mixtures in the olfactory system. 

Able, D. L, 1999, Scramble competition selects for greater tailfin size in male red-spotted newts (Amphibia Salamandridae), Behav. Ecol. Sociobiol. 46 423-428. 

Dawley, E. M., 1984, Identification of sex through odors by male red-spotted newts, Noiophihahnus viridescens, Hetpetologica 40 101-105. 

Gill, D. E., 1978, Meta-population ecology of red-spotted newt, Notophthalmus viridescens (Rafinesque), Ecol. Monogr. 48 145-166. 

Massey, A., 1988, Sexual interactions in red-spotted newt populations, Anim. Behav. 36 205-210. 

Park, D., McGuire, J. M., and Eisthen, H. L., Differential responses of large and small male red-spotted newts, Notophthalmus viridescens, to conspecific chemical cues, Copeia, submitted. 

Pool, T. B., and Dent, J. N., 1977, Neuronal regulation of product discharge from the hedonic glands of die red-spotted newt, Notophthalmus viridescens, J. Exp, Zool. 201 203-220. 

Verrell, P. A., 1985, Male mate choice for large, fecund females in the red-spotted newt, Notophthalmus viridescens. how is size assessed Hetpetologica 41 382-386. 

Rohr, J. R., Madison, D. M., and Sullivan, A. M., 2002, Sex differences and seasonal trade-ofis in response to injured and non-injured conspecifics in red-spotted newts, Notophthalmus viridescens, Behav. Ecol. Sociobiol. 52 385-393. 

Pool, T.B. Dent, J.N. 1977. The ultrastructure and the hormonal control of product synthesis in the hedonic glands of the red-spotted newt Notophthalmus viridescens. J. Exp. Zool., 201, 177—202. 

Verrell, P.A. 1982. The sexual behaviour of the red-spotted newt, Notophthalmus viridescens (Amphibia Urodela Salamandridae). Anim. Behav., 30, 1224-1236. 

Rowland, W.J., Robb, C.C. and Cortwright, S.A. 1989. Chemically-mediated mate choice in red-spotted newts do males select or just detect females Anim. Behav., 39, 811—813. 

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