High genetic diversity in cryptic populations of the migratory sutchi catfish Pangasianodon hypophthalmus in the Mekong River

So, N., Maes, G.E., and Volckaert, F.A.M. (2006) High genetic diversity in cryptic populations of the migratory sutchi catfish Pangasianodon hypophthalmus in the Mekong River. Heredity, 96. pp. 166-174.

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The detection and conservation of spawning units is of crucial importance in highly migratory species. The sutchi catfish Pangasianodon hypophthalmus (Pangasiidae; Teleostei) is a common large-sized tropical fish, which migrates annually to several upstream spawning sites on the Lower Mekong River and feeds on the huge floodplain of the Lower Mekong and Tonle Sap for the other half of the year. We hypothesised that because of the relative size of the feeding and spawning habitat, genetic variability would be high and homogeneous in foraging populations, but that spawning stocks would be distinct in space and time. To test these predictions, 567 individuals from 10 geographic locations separated by up to 1230 km along the Lower Mekong River were genotyped at seven microsatellite loci. The level of genetic diversity was much higher than other freshwater fish and reached values comparable to marine species (mean He=0.757). All samples collected at the potential spawning sites deviated from Hardy–Weinberg expectations, suggesting admixture. Individual-based clustering methods revealed genetic heterogeneity and enabled the detection of three genetically distinct sympatric populations. There was no evidence of recent reduction in effective population size in any population. Contrasting with the vast extent of the feeding grounds, the shortage of spawning grounds seems to have moved sutchi catfish towards diachronous spawning. Hence the sustainable exploitation of this natural resource hinges on the conservation of the limited spawning grounds and open migration routes between the spawning and feeding grounds.

Item ID: 30590
Item Type: Article (Research - C1)
ISSN: 1365-2540
Keywords: fisheries; microsatellites; migration; Pangasiidae; spawning; sympatry
Funders: BTC, Katholieke Universiteit Leuven, Mekong River Commission, International Foundation for Science (IFS)
Date Deposited: 24 Jul 2014 05:51
FoR Codes: 06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 70%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 30%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960807 Fresh, Ground and Surface Water Flora, Fauna and Biodiversity @ 60%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960699 Environmental and Natural Resource Evaluation not elsewhere classified @ 40%
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