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ABSTRACTS OF PRESENTATIONS IN ORDER PRESENTED development and geothermal development in the area. The habitat development will result in nearly a doubling of existing habitat at the site. Preliminary results of our University of Nevada, Reno contract investigating the taxonomic relationships of speckled dace (Rhinichthys osculus) populations indicate that fish from the Owens River drainage are more closely related to fish from the Lahontan drainage than the Colorado River drainage. The Amargosa River population is the most genetically distinct. The Department, based on the numerous Cyprinodon macularius found during a 1991 pupfish survey around the Salton Sea, effected a regulation change that eliminates or modifies bait fishing gear that could result in "take" of pupfish. The Department also provided some funding and collected fish for an Arizona State University electrophoretic study of Cyprinodon macularius. Additional ponds were developed at Shoshone Springs for Shoshone pupfish (Cyprinodon nevadensis shoshone). The habitat for this fish consists only of two artificial ponds which could be lost in a severe thunderstorm or other event. Molecular genetic studies of California (and some Nevada) pupfish populations will begin in November 1992. The study's primary focus is to examine the genetic relationships within Cyprinodon nevadensis complex and determine (at the subspecies level) from those in the Amargosa River. The study will also include samples from the following populations: Cyprinodon diabolis, Cyprinodon radiosus, Cyprinodon salinus ssp. and Cyprinodon macularius. RESUMEN RECEIVED TOO LATE TO BE TRANSLATED VRLIENHOEK, R. C.*; LEBERG, P. L. (RCV - Center for Theoretical & Applied Genetics, Rutgers Univ., New Brunswick, NJ 08903-0231; PLL - Dept. Biology, Univ. of Southwestern Louisiana, Lafayette, LA 70504.) Parasites and the Red Queen: the management of biological warfare in endangered populations / Parasitos y la Reina Roja: el manejo de la guerra biol6gica de las poblaciones en peligro KEYWORDS: parasites; genetic diversity; Red Queen; Poeciliopsis ABSTRACT Introduction of exotic species poses an additional threat against native fishes that can be waged by fellow travelers -- parasitic helminths, bacteria, and viruses. The ability of native populations to withstand these additional threats would be affected by their demographic stability and their level of genetic diversity. Competent immune surveillance and variation in susceptibility affect the rate at which parasites spread through a host population. According to Red Queen hypothesis, a host population of a long-lived species must evolve as fast as it can just to keep up in an evolutionary race with short-lived parasites. Because evolutionary rate is tied to genetic variability in the host population, variability must be maintained to allow native populations to stay in place with their native parasites and -to face the treat of exotic parasites. Field and laboratory studies with fishes in the genus Poeciliopsis were designed to examine critical assumptions on which the Red Queen hypothesis is based. Field studies revealed that genetic diversity in the host is associated with a lower parasite load. Laboratory experiments with these fish revealed genetic variation in susceptibility to a helminth parasite. The management implications for small endangered populations are discussed. RESUMEN La introducci6n de especies ex6ticas plantea de nuevo una amenaza adicional para peces nativos que pueden ser afectados por companeros viajeros--helmintos parasitos, bacterias y virus. La habilidad de las poblaciones nativas para resistir esta amenaza adicional podria estar afectada por su estabilidad demograpia y su nivel de diversidad gen6tica. La vigilancia inmune competente y la variaci6n en la susceptibilidad afectan la tasa en la cual los parasitos se propagan a trav6s de una poblaci6n hospedera. De acuerdo a la hip6tesis de la Reina Roja, una poblaci6n hospedera de una especie de vida larga podria desarrollarse tan rapido como pueda mantener una tasa evolutiva con parasitos de vida corta. Porque la tasa evolutiva esta ligada a variabilidad gen6tica en la poblaci6n hospedera, ]a variabilidad podria ser mantenida y permitir que poblaciones nativas permanezcan en el lugar con sus parasitos nativos y afrontar la amenaza de parasitos ex6ticos. Estudios de campo y laboratorio indican que la diversidad gen6tica en el hospedero esta asociada con una baja carga parasita. Experimentos de laboratorio con estos peces revelan variacion gen6tica en susceptibilidad a un helminto parasito. Se discuten las implicaciones de manejo para poblaciones pequefias en peligro. 16