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

Abstract

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 Crías 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 crías resultantes son posteriormente liberadas al medio silvestre. Para ser efectivos, los programas de reproducción suplementaria requieren estrategias cruzadas que maximicen la producción de crías 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 crías 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 ...

Multiple paternity increases effective population size

“…On the other hand, if thousands of males and females are in a mating system with temporal polyandry, the increased N e gained by the addition of simultaneous polyandry (MP) may have a less meaningful influence on the maintenance of genetic diversity in the population. Nonetheless, multiple mating by either sex will typically increase N e and decrease the variance in N e per generation, significantly improving the maintenance of genetic diversity in a conservation context (Fiumera et al. 2004).…”

Genetic variation of hatchery and wild stocks of the pearl oyster Pinctada fucata martensii (Dunker, 1872), assessed by mitochondrial DNA analysis

“…Since it is well known that the pearl qualities such as the color and thickness of the nacreous layer are decided genetically Komaru 1990, 1996), most culturists carry out selective breeding of the oysters in order to produce good-quality pearls in Korea and Japan. Additionally, P. fucata martensii is a highly fecund, broadcast spawning species (Matsui 1965), a combination of traits that, in hatcheries, can easily result in populations with low Ne due to the likelihood of a few individuals producing the majority of offspring in a given generation (Wada and Komaru 1994;Fiumera et al 2004). Broodstock that are subsequently chosen from such cohorts are also more likely to be closely related, which can lead to ongoing problems associated with inbreeding depression and significantly reduce the response to selection (Mgaya et al 1995;Evans et al 2004;Lind et al 2009).…”

Reduced Genetic Variation and Decreased Effective Number of Breeders in Five Year-Classes of Cultured Geoducks (Panopea generosa)

“…Isolating both males and females to release gametes individually would enable factorial crosses and avoid sperm competition. A complete factorial breeding scheme without equalizing family size comes Effective number of breeders (N b ) in wild and cultured Panopea generosa groups estimated using three methods: parentage without parents (Waples & Waples 2011), linkage disequilibrium (Hill 1981), and sibship assignment (Wang 2004, Wang & Santure 2009 closest to the goal of maintaining genetic diversity while maximizing progeny production (Fiumera et al 2004, Busack & Knudsen 2007, but partial factorial designs as small as two by two provide many of the benefits of full-factorial mating schemes (Busack & Knudsen 2007) and may be more manageable for hatchery personnel to conduct.…”