Asian elephant chemical signals

Rasmussen, L. E., Schmidt, M. J., and Daves, G. D., 1986, Chemical communication among Asian elephants. Chemical Signals in Vertebrates IV, D. Duvall, D. Muller-Schwarze and R. M. Silverstein, eds.. Plenum Press, New York, pp. 627-644. 

Rasmussen L.E.L. and Hultgren B. (1990). Gross and microscopic anatomy of vomeronasal organ in the Asian Elephant (Elephas maximus). In Chemical Signals in Vertebrates 5 (MacDonald D., Milller-Schwarze D. and Natynczuk S.E., eds.). Oxford University Press, pp. 154-161. 

Rasmussen L.E.L. and Schulte B. (1998). Chemical signals in the reproduction of Asian (Elephas maximus) and African (Loxodonta africana) elephants. Anim Reprod Sci 53, 19-34. 

Rasmussen, L.E.L. (1999) Evolution of chemical signals in the Asian elephant, Elephas maximus behavioural and ecological influences. J. Biosci. (Bangalore) 24, 241-251. 

Rasmussen, L.E.L. and Schulte, B.A. (1999) Ecological and biochemical constraints on pheromonal signaling systems in Asian elephants and their evolutionary implications. In R. Johnston, D. Miiller-Schwarze and P. Sorenson (Eds.), Advances in Chemical Communication in Vertebrates, Vol. 8 Kluwer Academic/Plenum Press, New York, pp. 46-62. 

Scott, N.L. and Rasmussen, L.E.L. (2005) Chemical communication of musth in captive Asian elephants, Elephas maximus. In R.T. Mason, M.R LeMaster and D. Miiller-Schwarze (Eds.), Chemical Signals in Vertebrates 10. Springer Press, New York, pp. 118-127. 

Abstract A relatively small number of mammalian pheromones has been identified, in contrast to a plethora of known insect pheromones, but two remarkable Asian elephant/insect pheromonal linkages have been elucidated, namely, (Z)-7-dodecen-1-yl acetate and frontalin. In addition, behavioral bioassays have demonstrated the presence of a chemical signal in the urine of female African elephants around the time of ovulation. Our search for possible ovulatory pheromones in the headspace over female African elephant urine has revealed for the first time the presence of a number of known insect pheromones. This search has been facilitated by the use of a powerful new analytical technique, automated solid phase dynamic extraction (SPDE)/GC-MS, as well as by novel macros for enhanced and rapid comparison of multiple mass spectral data files from Agilent ChemStation . This chapter will focus on our methodologies and results, as well as on a comparison of SPDE and the more established techniques of solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). 

Compared to the large number of chemical signals identified in insects, only a small number of proven mammalian pheromones are known, two of which have been identified in elephants (Albone 1984 Brown and Macdonald 1985 Wyatt 2003 Burger 2005). Female Asian elephants (Elephas maximus) release a... 

To begin the assessment of possible chemical messages between male Asian elephants, responses of captive males to conspecific musth and nonmusth urine were measured. Some obvious disadvantages of captive studies are substantially offret by some real advantages (1) close, accurate behavioral observations in a limited-size enclosure, (2) precise placement of test samples on substrate free of conflicting signals, (3) safe collection of test samples of elephant origin from males whose hormonal status can subsequently be determined. 

Results from the relative time spent investigating each sample demonstrate that the captive male Asian elephants in this study used chemical signals in urine to distinguish between musth and nonmusth urine. The males spent more time investigating the musth urine samples, perhaps to assess the relative dominance of the donor and status as a potential competitor for mates. Olfactory investigation of nonmusth urine shows that there are additional chemical signals other than those related to musth state present in excretions. 

Many similarities exist between the lifestyles and behaviors of Loxodonta africana and Elephas maximus, two of the three extant species of elephants (Sukumar, 2003 Poole, 1987, 1989a,b Rasmussen and Krishnamurthy, 2000 Rasmussen and Schulte, 1998). While the roles of olfaction and the chemical senses in Asian elephant society have been extensively investigated (Rasmussen and Greenwood, 2003 Rasmussen et al, 1997, 2002), similar investigations in the African species are limited to recent studies of chemical signals among males (Rasmussen and Wittemyer, 2002). 

Our standard control in these studies is vanilla extract in water. The control generally elicits a low level of interest, mainly sniffs and checks. We interpret this as interest in an odor source but not one with a meaningful signal (i.e., with evolutionarily evolved meaning). Female Asian elephants often show about the same interest in luteal urine as our control. However, luteal urine does evoke place and flehmen response on occasion, whereas, the control does not (Slade et al., 2003). Luteal urine probably contains cues on sender identity, but chemicals either specific to or more abundant in follicular urine reveal reproductive readiness. 

This paper focuses on the ecological and biochemical constraints imposed on such chemical communication. Our analysis of these constraints and their relationship to chemical communication will include (1) the evolution of chemical signals in elephants (2) the operational levels of chemical signals within elephant society (behavioral and/or physiological conditions of the emitters and responders are important constraints) and (3) the types of chemicals available as potential chemical signals. We will focus on two specific chemical signals to illustrate these constraints (1) volatile emissions from male Asian elephants in musth, and (2) (Z)-7-dodecenyl acetate, a female preovulatory pheromone. 

Table II. Temporal properties and chemical identities of potential chemical signals from temporal gland secretions of Asian male elephants in musth...

Rasmussen, L.E.L. Schulte, B.A. 1998. Chemical signals in the reproduction of Asian and African elephants. Anim. Reprod. Sci., in press. 

Rasmussen, L.E.L., Schmidt, M.J. Daves, G.D. 1986. Chemical communication among Asian elephants. In Chemical Signals in Vertebrates Evolutionary, Ecological, and Comparative Aspects (Ed. by D. Duvall, M. Silverstein D. Miiller-Schwarze), pp 627—646. New York Plenum Press. 

Rasmussen, L.E.L., Gunawardena, R.A. Rasmussen, R.A. 1997b. Do Asian elephants, especially males in musth, chemically signal via volatiles in breath Chem. Senses, 22, 775. 

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