Spatial genetic structure of Thai silver barb Puntius gonionotus (Bleeker) populations in Thailand.
Date
1996
Authors
Kamonrat, Wongpathom.
Journal Title
Journal ISSN
Volume Title
Publisher
Dalhousie University
Abstract
Description
Microsatellite DNA markers were developed from a Thai silver barb (Puntius gonionotus) genomic library and were then used to study various aspects of the genetics of P. gonionotus populations in Thailand. The aim is to provide means for evaluating management policies for the species in terms of conservation and genetic improvement.
Twelve natural populations from three rivers and 29 hatchery stocks from the central and north-east regions of Thailand were studied. Genetic variability was high in both groups of populations. Multidimensional scaling analysis of genetic distances revealed the discreteness apparent between watersheds among natural populations, and between geographic regions among hatchery stocks. High genetic variability within populations and significant genetic differentiation between populations both in native and hatcheries stocks indicate rich genetic resources of this species in Thailand. However, there was evidences that stock management may pose a threat of losing or altering genetic integrity of both natural and hatchery populations. Mixed stock analysis of the fish sampled from the rivers indicated 75% to 96% were from hatchery populations. This high genetic contamination of the natural populations was undoubtedly the consequence of restocking programs in which millions of P. gonionotus are released to rivers each year. Evidence of reduction of genetic integrity between regions was also observed in stations due to stock transfer. The results suggested an urgent need for genetically based stock management policies for both natural and hatchery populations.
The potential use of microsatellites for broodstock improvement in aquaculture was studied. Pedigrees of individuals were successfully established in a large communal rearing by using one to five microsatellites. The ability to identify individuals allowed a complicated genetic experiment and selective breeding to be conducted in places where facilities were limited. Results are considered to be more reliable because environmental variances are accounted for as fish are grown together from birth. In this study, heritability of growth traits in three stocks of P. gonionotus were estimated where all families were reared together. The estimates ranged from 0.193 to 0.523 suggesting that selective breeding in this species should result in good progress. However, heterozygosity in the largest individuals was greatly reduced, indicating that rapid inbreeding is very likely in simple means selection strategies.
Thesis (Ph.D.)--Dalhousie University (Canada), 1996.
Twelve natural populations from three rivers and 29 hatchery stocks from the central and north-east regions of Thailand were studied. Genetic variability was high in both groups of populations. Multidimensional scaling analysis of genetic distances revealed the discreteness apparent between watersheds among natural populations, and between geographic regions among hatchery stocks. High genetic variability within populations and significant genetic differentiation between populations both in native and hatcheries stocks indicate rich genetic resources of this species in Thailand. However, there was evidences that stock management may pose a threat of losing or altering genetic integrity of both natural and hatchery populations. Mixed stock analysis of the fish sampled from the rivers indicated 75% to 96% were from hatchery populations. This high genetic contamination of the natural populations was undoubtedly the consequence of restocking programs in which millions of P. gonionotus are released to rivers each year. Evidence of reduction of genetic integrity between regions was also observed in stations due to stock transfer. The results suggested an urgent need for genetically based stock management policies for both natural and hatchery populations.
The potential use of microsatellites for broodstock improvement in aquaculture was studied. Pedigrees of individuals were successfully established in a large communal rearing by using one to five microsatellites. The ability to identify individuals allowed a complicated genetic experiment and selective breeding to be conducted in places where facilities were limited. Results are considered to be more reliable because environmental variances are accounted for as fish are grown together from birth. In this study, heritability of growth traits in three stocks of P. gonionotus were estimated where all families were reared together. The estimates ranged from 0.193 to 0.523 suggesting that selective breeding in this species should result in good progress. However, heterozygosity in the largest individuals was greatly reduced, indicating that rapid inbreeding is very likely in simple means selection strategies.
Thesis (Ph.D.)--Dalhousie University (Canada), 1996.
Keywords
Biology, Genetics., Agriculture, Fisheries and Aquaculture.