DNA fingerprints of the Asian elephant in Sri Lanka, elephas maximus maximus, using multilocus probe 33.15 (Jeffreys)

Abstract

The elephant in Sri Lanka, with a population estimated to be about 4,000 at present, is threatened by the loss of its jungle habitat due to human activity centred around the development programmes of the country. The wild elephant population is fragmented, and restricted to a few isolated small habitats in protected areas. The maintenance of a high degree of genetic diversity within elephant subpopulations is vital for its long-term survival. Monitoring the degree of genetic heterogeneity in the geographical sub-populations of elephant is therefore an essential pre-requisite for this purpose. Although the maternal lineage of the elephant population in Sri Lanka has been examined previously, nuclear DNA has not been examined to gather complementary information. The aim of this study was to develop the methodology to obtain nuclear DNA fingerprints of the elephant with the multilocus human DNA probe 33.15 (Jeffreys), and to evaluate the probe to study the degree of genetic heterogeneity in the elephant population. A unique DNA fingerprint was obtained for each elephant DNA sample under the optimized conditions of hybridization (61°C in buffer containing 0.25 M sodium phosphate, 7% SDS, 1% BSA, 6% PEG, 10 mM EDTA and 0.25% dried milk, 100 ng/15 ml probe) developed during the study. A pair-wise comparison of DNA banding patterns of 8 individuals in the 3 - 23 kb region revealed a mean band sharing coefficient of 0.307 ±0.085. A total of 57 variable banding positions were observed and the mean number of bands per individual was 19 ±2.14. The calculated heterozygosity values for the unrelated and related individuals were 0.73, and 0.57 (mean) respectively. The study clearly demonstrated that the 33.15 probe is highly suitable to monitor the degree of genetic heterogeneity in the geographical sub-populations of the Asian elephant.