Conservation in Practice Maximizing Offspring Production While Maintaining Genetic Diversity in Supplemental Breeding Programs of Highly Fecund Managed Species

Supplemental breeding is an intensive population management strategy wherein adults are captured from nature and spawned in controlled settings, and the resulting offspring are later released into the wild. To be effective, supplemental breeding programs require crossing strategies that maximize offspring production while maintaining genetic diversity within each supplemental year class. We used computer simulations to assess the efficacy of different mating designs to jointly maximize offspring production and maintain high levels of genetic diversity (as measured by the effective population size) under a variety of biological conditions particularly relevant to species with high fecundity and external fertilization, such as many fishes. We investigated four basic supplemental breeding designs involving either monogamous pairings or complete factorial designs (in which every female is mated to every male and vice versa), each with or without the added stipulation that all breeders contribute equally to the total reproductive output. In general, complete factorial designs that did not equalize parental contributions came closest to the goal of maximizing offspring production while still maintaining relatively large effective population sizes. Next, we estimated the effective population size of 10 different supplemental year classes within the breeding program of the robust redhorse (Moxostoma robustum). Two year classes failed to produce progeny, whereas successful year classes used partial factorial designs to realize effective sizes ranging from 2 to 26 individuals. On average, a complete factorial design could increase the effective size of each robust redhorse supplemental year class by 19%. Programas Reproductivos Suplementarios para Especies Bajo Manejo: Estrategias para Maximizar la Producción de Cŕıas y Mantener la Diversidad Genética en Taxones Altamente Fecundos Resumen: La reproducción suplementaria es una estrategia de manejo intensivo de poblaciones en la que se capturan adultos silvestres, desovan en condiciones controladas y las cŕıas resultantes son posteriormente liberadas al medio silvestre. Para ser efectivos, los programas de reproducción suplementaria requieren estrategias cruzadas que maximicen la producción de cŕıas mientras se mantiene la diversidad genética dentro de cada clase suplementaria anual. Utilizamos simulaciones de computadora para evaluar la eficacia de diferentes diseños de apareamiento para conjuntamente maximizar la producción de cŕıas y mantener niveles altos de diversidad genética (medida por el tamaño poblacional efectivo) bajo una variedad de condiciones biológicas particularmente relevantes para especies de alta fecundidad y fecundación externa, como muchos peces. Investigamos cuatro diseños básicos de reproducción suplementaria involucrando apareamientos monógamos o diseños completamente factoriales (en los que cada hembra es apareada con cada macho y viceversa), cada uno con o sin la estipulación de que todos los reproductores contribuyen equitativamente al total de la reproducción. En general, los diseños factoriales que no igualaron las contribuciones parentales fueron los más cercanos a la meta de maximizar la producción de cŕıas y mantener tamaños poblacionales efectivos ‡Current address: Department of Molecular Biology and Genetics, 227 Biotechnology Building, Cornell University, Ithaca, NY 14853–2703, U.S.A., email [email protected] §Current address: Department of Biology, Duquesne University, Pittsburgh, PA 15282, U.S.A. Paper submitted December 2, 2002; revised manuscript accepted August 28, 2003.