ENEMY PHENOMENON IN SOUTHERN RED-BACKED SALAMANDERS. Kenzie Medley, Biology. Faculty Advisor: Dr. Alicia Mathis The “dear enemy” hypothesis states that a territory owner shows reduced aggression toward a neighbor once territorial boundaries are established. Neighbors that do not restrict their activity to the agreed upon territory boundaries can be characterized as “cheaters” and might be subject to retaliation. To establish territory boundaries, we exposed each focal Southern Red-backed Salamander, Plethodon serratus, to reflections produced from a mirror located on one side of an arena for a week. To simulate a cheating neighbor, we moved the mirror to the other side of the arena; a cooperating neighbor was simulated by replacing the mirror in its original location. Salamanders exposed to the cheating “neighbor” were significantly more aggressive than salamanders exposed to the cooperating “neighbor”. Discrimination against “cheating” neighbors is consistent with the dear enemy hypothesis.