The Analysis Of Genetic Diversity Of Chinese Alligator(Alligator Sinensis) And Molecular Phylogeny Of Five Species Of Crocodiles

The AFLP (Amplified Fragment Length Polymorphism) technique is based on the selective PCR amplification of restriction fragments from genomic DNA digested by restriction enzymes completely. It is a powerful technique with dominant DNA molecular marker for polymorphism detection, and is applicable to DNA from any organisms without prior knowledge about the genomic makeup of the organism. The technique has been widely applied to the study of animal molecular biology.Chinese alligator (Alligator sinensis) is an endemic endangered species in China. AFLP was employed to characterize the genetic diversity within and between Changxing Subpopulation (CXSP) and Xuanzhou Subpopulation (XZSP). The results suggest that XZSP and CXSP have the similar origin, supported by both dendrogram analysis and geographic evidence. There are very low genetic variation existing in the population due to bottleneck events and small effective population size. Three individuals, C9904, XFi9915 and XF]9933 , were found with more genetic diversity in current study, so it will be better to offer more copulation chance to these individuals in captive breed plan.Portion of mitochondrial DNA control region form 39 individuals which belong to CXSP and XZSP respectively were sequenced in the study. All individuals share only one haplotype inferring no polymorphism has been found in the control region of Chinese alligator. The explanation for the phenomena is due to the result of bottleneck in history. This situation is not changed with the increase captive population size. Two captive populations couldn't be defined as separate evolutionary significant units (ESUs) because of lacking of genetic divergence between them, and should be considered as a single ESU in the conservation of the species. By comparing the sequences of control region of mitochondrial DNA from three species of crocodiles, it is revealed that the smallest genetic diversity exists between Alligator sinensis and Alligator mississipiensis.A portion of mitochondrial ND4 and cytochrome b gene of 3 species of crocodilian was sequenced. Additional homologous sequences of Alligator mississipiensis and Caiman crocodilus from GenBank were aligned together and compared with Chelonia mydas. The phylogenetic trees were reconstructed. Alligator sinensis is more related to Alligator mississippinesis than others.