NSF Award Abstract - #0217068

AWSFL008-DS3

Collaborative Research: Development and Identity of Sexually Dimorphic
Reproductive Signals and Responses by African Elephants

Abstract

Collaborative Research: RUI - Development and Identity of Sexually Dimorphic Reproductive Signals and Responses by African Elephants

In the spirit of the BIO C-RUI program, this proposal crosses disciplinary, departmental, and institutional boundaries. The project will answer five questions regarding the proximate mechanisms of reproductive communication using innovative techniques at the interface of biology and chemistry. African elephants will be used to test hypotheses on developmental patterns of sexually dimorphic reproductive signals and responses. This is not only for the distinct advantages elephants offer as a research model, but also because basic scientific research can provide knowledge about these ecologically important, endangered animals that may aid in their long-term survival. This research team includes an animal behaviorist (Dr. Schulte) and an organic chemist (Dr. Goodwin), each with a track record of successful elephant-related research at predominantly undergraduate institutions. Dr. Rasmussen, who characterized the pre-ovulatory pheromone in Asian elephants and has made substantial contributions to the understanding of elephant biochemistry, behavior and olfaction, joins the team. These scientific collaborators are educators who believe that undergraduates learn science best by doing science, i.e. by research participation with scientists, presentation of results at scientific meetings, and co-authoring manuscripts. Undergraduate collaborators will actively participate in this research on sexually dimorphic reproductive signals and responses. Polygamous animals often display extreme sexual dimorphism, where males and females may live in very different social structures. In mammals, females typically raise the offspring often with little or no male assistance. African elephants (Loxodonta africana) illustrate this pattern very well. Intersexual interaction is especially prevalent during the breeding season when individuals use a variety of communicative behaviors to compete for and select mates as well as maintain social bonds. Chemical signals and related tactile behaviors are primary means of evaluating reproductive condition and attracting mates. The development of chemical signal production and sex-specific responses has received little attention. In fact, sexually dimorphic communication patterns related to reproduction have rarely been compared within the same species simultaneously in a single study. Focal questions in these arenas are posed in three sets: SET I: What are the specific chemical signals in pre-ovulatory urine that: A. Elicit male reproductive behavior? B. Elicit heightened female social responsiveness? SET II: During the differential development of males and females are there recognizable stages of: A. Male responses toward pre-ovulatory urine and its specific chemical signal(s)? B. Female responses toward pre-ovulatory urine and its specific chemical signal(s)? SET III: Based on the results in the first two sets, what are the comparative ontogenetic patterns of male and female responses toward known chemical signal sources and to specific signal compounds and more generally in the display of reproductively related behaviors? These questions are investigated first by a study of female-to-male signals (IA and IIA), then female-to-female signals (IB and IIB) and finally by comparing the two developmental pathways (III). Specifically, answers are sought by: (i) Collecting urine from captive and wild female African elephants; (ii) Performing behavioral bioassays of urine samples for the responses of both male and female conspecifics; (iii) Chemically analyzing bioactive urine fractions to identify organic compounds; (iv) Bioassaying selected urinary components with captive and then wild African elephants; (vi) Observing wild African elephants for reproductive chemotactile communication. The proposed research will identify proximate chemical causes of reproductive behavior and elucidate sexually dimorphic developmental patterns of communication. This study will lay the groundwork for future investigation on male based signals and of ultimate questions on this topic. The findings may assist in the conservation of endangered elephants in practice and other species.