Salamander reproduction

Dawley, E. M., 1992, Sexual dimorphism in a chemosensory system the role of the vomeronasal organ in salamander reproductive behavior, Copeia 1992(1) 13-120. 

My goals in this paper are to review the role of courtship pheromone delivery in salamander reproduction, and to consider this behavior in terms of sexual selection. I first summarize breeding patterns of aquatic and terrestrial salamanders [since the timing and mode of delivery of these pheromones can be very different in an aquatic versus a terrestrial medium],... 

Evidence from these three levels—courtship observations, morphology and experimental courtship manipulations—is summarized below. Most information is available for salamanders in three families (Ambystoma-tidae, Salamandridae, and Plethodontidae) which account for the majority of salamander species living today. The information below is not intended to duplicate detailed reviews of salamander reproduction and courtship behavior (e.g., Arnold, 1972, 1976, 1977 Houck, 1977, 1982 Joly, 1966 Organ, 1961 Salthe, 1967). Instead, I focus on specific examples that highlight the diversity of modes with which males deliver courtship pheromones to females. 

Major sensory stimuli important to salamander reproduction can include visual stimuli (e.g., Himstedt, 1979 Malacarne and Curtassa, 1983 Verrell, 1982b), tactile stimuli, and olfactory stimuli other than courtship pheromones (Margolis, 1980 Roth, 1976). Moreover, the effects of any sensory signals on any animal can depend strongly on daily and seasonal changes in motivational states (Halliday, 1977 Halliday and Sweatman,... 

Amphibians such as frogs and salamanders depend heavily on temporary ponds for breeding. These ponds are highly vulnerable to the "acid shock" events associated with storms or snowmelt. In several studies, reproduction of amphibians has been shown to be seriously restricted when acidity of their habitat decreases to a pH value of less than 5 14). 

The demonstration of this behavioural response to a male pheromone signal is significant because of the manner in which the pheromone was delivered. Most other vertebrate examples of reproductive pheromones involve reception via the olfactory system(s). In contrast, D. ocoee females received the pheromone via diffusion through the dorsal skin. We assume that the well developed superficial capillary system of these lungless salamanders is the route by which the male pheromone was transported to whatever target tissue(s) initiated responses that affected female reproductive behaviour. 

Arnold, S.J. (1977) The courtship behavior of North American salamanders with some comments on Old World salamandrids. In D. Taylor and S. Guttman (Eds.), The Reproductive Biology of Amphibians. Plenum Press, New York, pp. 141-183. 

Larson, A., Weisrock, D.W. and Kozak, K. H. (2003) Phylogenetic systematics of salamanders (Amphibia Caudata), a review. In D.M. Sever (Ed.), Phytogeny and Reproductive Biology of Urodela (Amphibia). Science Publishers Inc., Enfield, New Hampshire, pp. 31-108. 

Reproductive failure of some acid-sensitive species of amphibians such as spotted salamanders, Jefferson salamanders, and the leopard frog... 

Butte Lake, British Columbia, do not undergo oxidative diagenesis because of a rapid rate of accumulation and short exposure time to dissolved oxygen in bottom waters. In Michigan, lakes with elevated concentrations of copper (34.0p,g/L) have low densities of fish populations. In the Elizabeth River estuary of southern Chesapeake Bay, anthropogenic copper and other chelatable metals are present at concentrations sufficient to adversely affect growth and survival of the copepod Acartia tonsa. In Norway, freshwater fish are present only when copper is less than 60.0p,g/L and some humic acids are present. Successful reproduction of the spotted salamander (Ambystoma maculatum) occurs at low water concentrations of copper (<10.0p,g/L), lead, and aluminum, and high concentrations of silicon. Failed reproduction occurs at low water concentrations of silicon, and elevated concentrations of copper (>25.0p,g/L), lead, and aluminum. 

Sexual isolation has arisen among numerous species of geographically isolated populations of salamanders (review by Arnold et al., 1993). Behavioral experiments indicate that the degree of reproductive isolation is stronger between sympatric species of large Plethodon than it is between allopatric populations of these species (Reagan, 1992). Sexual isolation may be due to species-specific differences in the chemosensory systems... 

In this terrestrial salamander system, chemical signals are broadcast in the environment by reproductively active females and are detected by the males as they tap... 

Mathis, A., 1989, Do seasonal spatial distributions in a terrestrial salamander reflect reproductive behavior or territorialitj Copeia 1989 788-791. 

Arnold, S.J. 1977. The evolution of courtship behavior in New World salamanders with some comments on Old World salamanders. In The Reproductive Biology of Amphibians (Ed. by D.H. Taylor S.I. Guttman), pp. 141—183. New York Plenum Press. 

Salamander courtship pheromones produced by male P. jordani share the basic characteristics of substances known to affect female reproductive behavior. The R jordani extract was comprised primarily of glycoproteins, including highly stable and non-volatile... 

Arnold, S.J., Reagan, N.L, Verrell, PA. 1993. Reproductive isolation and speciation in plethodontid salamanders. Herpetologica 9 216-228. 

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