 Reference Base  Characterization of a species-specific repetitive DNA fro... |
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Ali, Md. S.; Asim, A.S.; Bashamboo, S.; Anu; Mathur, T.K.; Malik, P.K.; Mathur, V.B.; Raha, A.K.; Ansari, S., 1999. Characterization of a species-specific repetitive DNA from a highly endangered wild animal, Rhinoceros unicornis, and assessment of genetic polymorphism by microsatellite associated sequence amplification (MASA). Gene 228: 33-42, fogs. 1-5, table 1
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| Location: |
World |
| Subject: |
Taxonomy - Evolution |
| Species: |
Indian Rhino |
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3.6. Phylogenetic relationship of rhino with other species based on MASA analysis
The oligo primer OAT15.2 used for MASA showed genome-specific amplicons with DNA samples from rhino and other vertebrate species (data not shown). As mentioned earlier, based on the average percentage of matched bands using Diversity One Version 1.6 soft- ware (PDI, New York, USA), a phylogenetic tree was constructed to ascertain the genetic affinities of rhino with other vertebrate species with respect to OAT15.2 repeat loci (Fig. 4b). Rhino samples from Jaldapara and Assam form one cluster but still these two main- tained separate units, whereas the other vertebrate species, depending upon their genetic affinities, segregated accordingly. The phylogenetic tree in the present study is specific to OAT 15.2 repeat loci and may not be construed for final positioning of a clad in the context of molecular systematics. Amplicons generated by MASA using other oligo primers were not used for construction of a phylogenetic tree, because primers OAT15.2 and OAT18.2 both carry similar sequence repeat motif whereas primer 033.15 revealed numerous bands (not shown).
4.2. Genetic similarities among R. unicornis
Among all the samples of R. unicornis, the overall similarity with respect to pSS(R)2 locus was found to be 86%. All the animals from a single geographical habitat segregated together owing to their genetic affinities (Fig. 4a). Jaccard's similarity coefficient showed that in the cluster, a single male ('F') from a different location forms a separate unit. The apparent genetic similarity among the six samples and relatively limited variation between these six and the single male is not surprising, because all six samples originated from one (Jaldapara) habitat in West Bengal, whereas male 'F' from the National Zoological Park was of Assam origin. This is a significant observation indicating at least some level of genetic variation between the two isolated populations. In the light of this observation, the animals from these two populations may be considered for reshuffling to achieve infusion of unrelated genetic material in the two confined gene pools. The low level of genetic diversity (Sulaiman and Hasnain, 1996; Ali et al., 1999) is likely to cause inbreeding depression.
On the population front, loss of a single male that has already sired several offspring will be less damaging compared with the one that has not. Thus, total protection of the rhino populations by strict control on poaching would allow them to maintain a natural level of heterozygosity while propagating their germplasm in an unconstrained manner. Notwithstanding present results, conclusive evidence may be obtained only if similar analyses were conducted on a larger number of samples from other areas to gain an insight into intraspecies genetic variations. This would also enable the delineation of rhinos from different Indian populations into a single clad or possible sub-species.
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