Publication Date

Summer 2016

Advisor(s) - Committee Chair

Dr. Bruce A. Schulte (Director), Dr. Jarrett R. Johnson, and Dr. Michael E. Smith

Degree Program

Department of Biology

Degree Type

Master of Science

Abstract

Asian elephants utilize two chemical signals that have been described to function in reproduction: (1) (Z)-7-dodecenyl acetate (Z7-12:Ac) is released by females near ovulation, and (2) frontalin is released by males around the time of musth. Signaling theory posits that the concentration at which either compound is emitted should have implications for the response of the receiver, varying with factors such as sex and reproductive experience. Here, the objectives were to: (1) investigate the effect of concentration on receiver chemosensory behavior in an effort to identify detection thresholds and concentrations of maximum response for reproductively experienced or inexperienced male and female Asian elephants, and (2) characterize the broader behavioral impacts of each of these compounds in an effort for application as environmental enrichment in captive settings. Concentrations from 0.0 mM to 2.0 mM of both frontalin and Z7-12:Ac were bioassayed simultaneously with captive elephants housed at facilities across North America in two experiments: one that tested mid-range concentrations and a second that tested low and high concentrations. There was a general increase in chemosensory response with increasing concentration of both compounds regardless of sex or reproductive experience. Females exhibited a lower detection threshold for frontalin, and the opposite was true for males with Z7-12:Ac. Reproductive experience also influenced thresholds: inexperienced males had a higher threshold than experienced males for frontalin (the same was true for females), and experienced males were able to detect Z7-12:Ac samples as low as 10–7 mM. Aside from inexperienced males, all elephants responded maximally to the 1.0 mM samples of both compounds. Elephants exposed to mid-range concentrations of either compound showed no notable changes in behavior after application of the signals, although inexperienced males spent less time inactive and more time walking after frontalin bioassays, and inexperienced females foraged more after exposure to Z7-12:Ac. Interpreted together, this suggests that the concentration at which either compound is emitted has strong implications for chemosensory response based on the identity of the receiver in Asian elephants, although it is unclear whether these compounds have other behavioral effects that can be targeted for a goal-oriented olfactory enrichment program.

Disciplines

Animal Sciences | Animal Studies | Biology

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