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Spatio-temporal genetic variability of sea trout populations in Northwestern Spain
Abstracts / Aquaculture 272S1 (2007) S238–S321
S247
Relatively little information is available on the magnitude of inbreeding depression. In the present study we mated 20 sires and 35 dams in such a way that their offspring had inbreeding coefficients of 0, 3.1, 6.3, 9.4, 12.5 and 25%. The fry were produced in hapas suspended in fertilized ponds. Fry were individually tagged with Floy® tags. In total 1904 fish were stocked in two fertilized earthen ponds for grow-out. After an over-wintering period, 410 fish were harvested and measured for body weight. Inbreeding significantly affected body weight at tagging and survival. Results indicated that higher inbreeding coefficients are associated with lower body weights at tagging and a reduced survival. No significant effect of inbreeding was found on body weight at harvest.
similarity and components of fitness. As expected, more highly related parents produced progeny with lower survival (i.e. inbreeding depression). Surprisingly, however, the surviving progeny of genetically similar parents had higher growth (outbreeding depression or heterosis) than less related parental pairs. We discuss potential mechanism underlying these patterns and their implications for aquaculture and selective breeding.
doi:10.1016/j.aquaculture.2007.07.037
J.L. Campos a , P. Morán a, D. Posada a, P. Caballero b a Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, 36310 Vigo, Spain b Dirección Xeral de Conservación da Natureza, Consellería de Medio Ambiente, Xunta de Galicia, C/ San Lázaro s/n, 15781 Santiago de Compostela, Spain
Inbreeding effects on growth and survival in a naturalized population of the Pacific oyster (Crassostrea gigas) revealed using molecular marker-based estimates of parental relatedness M.D. Camara a, S. Evans b, C. Langdon b a USDA-Agricultural Research Service, Hatfield Marine Science Center 2030 SE Marine Science Dr. Newport, OR 97365, USA b Molluscan Broodstock Program, Hatfield Marine Science Center 2030 SE Marine Science Dr. Newport, OR 97365, USA Inbreeding is an important factor influencing mating systems, dispersal mechanisms, and variation in life history traits within and among populations and thus has profound implications in evolutionary biology, selective breeding, conservation biology, and even medicine. In theory, high fecundity species such as elm trees and oysters are expected to have higher genetic load and consequently more severe inbreeding depression than low fecundity species, and previous studies have confirmed that self-fertilization, brother/sister matings, and cousin/cousin matings in C. gigas produce progeny with lower growth and survival than non-consanguineous pairings of parents. It is unclear, however, whether these effects can be extrapolated to the lower levels of consanguinity expected in natural populations with random mating. We studied inbreeding in a naturalized population of Pacific oysters using molecular markerbased estimates of parental relatedness calculated from multi-locus microsatellite genotypes. Using analysis of covariance approaches, we found significant relationships between estimators of parental genetic
doi:10.1016/j.aquaculture.2007.07.038
Spatio-temporal genetic variability of sea trout populations in Northwestern Spain
Genetic variation at five microsatellite loci was investigated in six sea trout populations sampled in 1997 and 2003 to describe the spatio-temporal genetic variation in the southern limit of anadromy of this species (Northwestern Spain). Previous ecological studies that screened reproductive parameters, age structure and biometry of these populations have suggested the existence of differentiation among these anadromous populations. Accordingly, we have observed a significant genetic variation between basins and an isolation by distance genetic pattern. However, we did not detect significant temporal genetic differentiation between temporal samples within rivers. All the studied populations suffered an important decline during 1998, however we have not detected genetic consequences. The lack of significant variation among temporal samples suggests that these populations are very stable with a high effective population size. We recommend that these genetic differences and the previous ecological data should be taken into account for any management activities in the future. However, given the high genetic variability and temporal stability observed we suggest that no supportive breeding programs should be carried out in these populations. Instead, improving habitat conditions seems to be a more appropriate conservation strategy. doi:10.1016/j.aquaculture.2007.07.039
S247
Relatively little information is available on the magnitude of inbreeding depression. In the present study we mated 20 sires and 35 dams in such a way that their offspring had inbreeding coefficients of 0, 3.1, 6.3, 9.4, 12.5 and 25%. The fry were produced in hapas suspended in fertilized ponds. Fry were individually tagged with Floy® tags. In total 1904 fish were stocked in two fertilized earthen ponds for grow-out. After an over-wintering period, 410 fish were harvested and measured for body weight. Inbreeding significantly affected body weight at tagging and survival. Results indicated that higher inbreeding coefficients are associated with lower body weights at tagging and a reduced survival. No significant effect of inbreeding was found on body weight at harvest.
similarity and components of fitness. As expected, more highly related parents produced progeny with lower survival (i.e. inbreeding depression). Surprisingly, however, the surviving progeny of genetically similar parents had higher growth (outbreeding depression or heterosis) than less related parental pairs. We discuss potential mechanism underlying these patterns and their implications for aquaculture and selective breeding.
doi:10.1016/j.aquaculture.2007.07.037
J.L. Campos a , P. Morán a, D. Posada a, P. Caballero b a Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, 36310 Vigo, Spain b Dirección Xeral de Conservación da Natureza, Consellería de Medio Ambiente, Xunta de Galicia, C/ San Lázaro s/n, 15781 Santiago de Compostela, Spain
Inbreeding effects on growth and survival in a naturalized population of the Pacific oyster (Crassostrea gigas) revealed using molecular marker-based estimates of parental relatedness M.D. Camara a, S. Evans b, C. Langdon b a USDA-Agricultural Research Service, Hatfield Marine Science Center 2030 SE Marine Science Dr. Newport, OR 97365, USA b Molluscan Broodstock Program, Hatfield Marine Science Center 2030 SE Marine Science Dr. Newport, OR 97365, USA Inbreeding is an important factor influencing mating systems, dispersal mechanisms, and variation in life history traits within and among populations and thus has profound implications in evolutionary biology, selective breeding, conservation biology, and even medicine. In theory, high fecundity species such as elm trees and oysters are expected to have higher genetic load and consequently more severe inbreeding depression than low fecundity species, and previous studies have confirmed that self-fertilization, brother/sister matings, and cousin/cousin matings in C. gigas produce progeny with lower growth and survival than non-consanguineous pairings of parents. It is unclear, however, whether these effects can be extrapolated to the lower levels of consanguinity expected in natural populations with random mating. We studied inbreeding in a naturalized population of Pacific oysters using molecular markerbased estimates of parental relatedness calculated from multi-locus microsatellite genotypes. Using analysis of covariance approaches, we found significant relationships between estimators of parental genetic
doi:10.1016/j.aquaculture.2007.07.038
Spatio-temporal genetic variability of sea trout populations in Northwestern Spain
Genetic variation at five microsatellite loci was investigated in six sea trout populations sampled in 1997 and 2003 to describe the spatio-temporal genetic variation in the southern limit of anadromy of this species (Northwestern Spain). Previous ecological studies that screened reproductive parameters, age structure and biometry of these populations have suggested the existence of differentiation among these anadromous populations. Accordingly, we have observed a significant genetic variation between basins and an isolation by distance genetic pattern. However, we did not detect significant temporal genetic differentiation between temporal samples within rivers. All the studied populations suffered an important decline during 1998, however we have not detected genetic consequences. The lack of significant variation among temporal samples suggests that these populations are very stable with a high effective population size. We recommend that these genetic differences and the previous ecological data should be taken into account for any management activities in the future. However, given the high genetic variability and temporal stability observed we suggest that no supportive breeding programs should be carried out in these populations. Instead, improving habitat conditions seems to be a more appropriate conservation strategy. doi:10.1016/j.aquaculture.2007.07.039