Genetic and morphometric studies to differentiate between wild and domestic Asian water buffaloes (Bubalus bubalis) and their hybrids in Kaziranga National Park, Assam, India.

摘要

Wild Asian water buffaloes (Bubalus bubalis) in Kaziranga National Park (KNP) are facing the threat of extinction due to hybridization with domestic water buffaloes. There are three types of buffaloes in KNP wild, domestic swamp and their hybrid. Measurements from photographs of frontal view were used to differentiate among types. Principal component analysis indicates that domestic buffaloes are a distinct group separate from both hybrid and wild. However, hybrid and wild have extensive overlap in their principal component scores. Discriminant function analysis separates domestics from wild with a classification error of 13%. Pair-wise comparison of hybrid and wild yields a classification of error of 49%. A classification scheme based on photographic measurements is presented primarily as a management tool. Seventeen bovine microsatellite loci developed in cattle were used without any modification to examine for genetic differences among types. In addition to routine source of DNA (blood and organ tissue), a remote method of skin biopsy was used to sample hybrid and wild buffaloes. A fourth group of buffaloes (domestic river type) was also included in the microsatellite analysis from New Delhi. Average heterozygosity for the four types of buffaloes varies from 0.59 to 0.67, wild buffaloes being the least and domestic swamp being the most heterozygous for the 17 loci typed. Principal component analysis of allele frequencies indicate that wild type are a distinct group, domestic swamp and river are closest and domestic hybrids being intermediate but closer to domestics. An interesting finding of the present study was that domestic swamp and liver buffaloes are closest with a genetic distance of D_S = 0.0537, and D_A = 0.0515. These distances are lower than expected for the sub-species differences. It is concluded that domestic swamp buffaloes from KNP are similar to river type, and that the wild buffaloes are still a distinct group fully worthy of conservation efforts.