Genetic characterization of Clariid catfish (Clarias Macrocephalus) and its hybrid (female Clarias macrocephalus X male Clarias gariepinus) in Thailand | |
| Author | Goel, Amit Kumar |
| Call Number | AIT Thesis no. AQ-00-26 |
| Subject(s) | Catfishes--Genetics--Thailand Hybridization |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. AQ-00-26 |
| Abstract | The culture of hybrid catfish, the hybrid between the native female Clarias macrocephalus and the exotic male Clarias gariepinus, is currently one of the fastest growing sectors of aquaculture in Thailand. The rapid expansion of hybrid catfish culture has also led to concerns about its impacts on genetic diversity of other species and on natural and pure stocks of Clariidae. It is possible that the F 1 hybrid can successfully be used as broodstock for the production of later generation and/or backcross hybrids that may lead to hybrid introgression and loss of unique F 1 hybrid genotypes. This has implication for both aquaculture (through the loss of the desired characteristics of the F 1 hybrid) and for wild populations of the indigenous catfish, which may become introgressed. Allozyme study had indicated that some introgression of C. macrocephalus stocks might be occurring (Chaiparinya 1996). However, DNA markers can be more reliable and informative and involve simpler sampling protocols. Therefore, the nuclear genome was analysed using the nuclear DNA marker, CH4 exon and an alternative marker using restriction fragment length polymorphism (RFLP) of the ND 516 portion of the mitochondrial DNA was also developed. This study suggested that possession of double banded genotype in nmthern population of C. macrocephalus, from Nan, might be an indicative of C. gariepinus introgression. However, other factors, such as non-specific amplification, might be causative of occurrence of double-banded pattern in C. macrocephalus. Elsewhere, C. macrocephalus populations populating the other regions of Thailand did not show any sign of C. gariepinus fixed double banded genotype. These findings suggest that the hybrid introgression be in its early stage. However, if situation persists, ceaseless introgressive hybridization may be deleterious to existing genetic resources of the Clariidae in Thailand. These results also suggest that for introgression studies the use of mitochondrial DNA marker is not very useful especially when only one way hybridization is going on and introgression is not extensive. However, an appropriate nuclear DNA marker(s) coupled with indigenous knowledge and an informed sampling strategy will enable a full understanding of the introgression issue in Clariidae in Thailand |
| Year | 2000 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AQ-00-26 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Mair, Graham C.; |
| Examination Committee(s) | Macaranas, Julie M.;Stevens, W.F.;Bart, Amrit; |
| Scholarship Donor(s) | H. M. The Queen of Thailand; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2000 |