Analysis of Male Agonistic Interactions in the Weakly Electric Fish, Brienomyrus brachyistius (Mormyridae) using a New Technique for Separating Electric Discharges
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The weakly electric mormyrid fish Brienomyrus brachyistius employs its electrosensory modality for the dual purposes of electrolocation and communication. The dominance relationship in mormyrids such as B. brachyistius can be described by two distinct phases: the initial phase of status determination and the ensuing phase of status maintenance. Much is known about the motor and electrical behavior of mormyrids in the initial phase of dominance, but much less is known about the second phase. This is due in large part to the technical difficulties associated with efficiently and accurately isolating the electric organ discharges (EODs) from individual fish. Through the use of a new EOD separation technique, G-PRIME, this study has been able to examine agonistic interactions during the second phase of dominance, status maintenance. This study describes G-PRIME and examines its accuracy, speed, and the volume of data it is able to handle. We also examined territoriality in this species and observed that territoriality was not present under these experimental conditions; rather a stable dominance hierarchy was in place. Additionally, the previously described sequence of pulse intervals (SPIs) "long cessation," "short cessation," and "pulse pairs" were observed and expanded upon by quantitative analysis, and a novel SPI termed the "long repeated acceleration-deceleration" (LRAD) was observed and analyzed. Adaptive functions of described SPIs are discussed as well as a possible neuronal mechanism of production of pulse pairs.
dissertation or thesis