DNA antigo de amostras de ossos de baleia-franca-austral, Eubalaena australis (Desmoulins, 1822) (Mysticeti, Cetartiodactyla) no Atlântico Sul Ocidental

Abstract

The Southern Right Whale (Eubalaena australis) was object of great commercial exploitation between the XVII and XX centuries in the Southern Hemisphere. Recent surveys suggest that the world’s population is of 12,000 specimens, which would represent 17% to 21% of its original size. Despite the supposed recovery, the drastic populational decline, resultant from 400 years of hunting activities, could have generated high levels of endogamy, low reproduction capacity and loss of genetic variability of the species, compromising their potential of adjustment, thus increasing their probability of extinction. Due to the exposed, it is of extreme importance the comparative evaluation of the genetic variability between the current E. australis population and representative samples from the hunting period, especially from Brazilian coast. Therefore, the purpose of this study was: I. To optimize and compare extraction and amplification methods of aDNA from Southern Right Whale’s bones in different stages of deterioration; II. To genetically characterize segments of the mtDNA’s D-Loop region from E. australis bones collected at Península Valdés in Argentina and Santa Catarina in Brazil, and III. To compare nucleotide sequences of the recovered region from aDNA samples with those described for the current populations. This study compared five different extraction methods in order to obtain genetic material from deteriorated samples. The extraction method containing Dextran Blue reagent showed the higher efficiency. With the amplification of 20 short fragments and overlapping of aDNA through Nested-PCR technique, and further cloning of the latter fragment, it was possible to sequence small fragments, varying from 7 to 59 pb, from the mtDNA’s D-loop region from 11 bones samples of E. australis, out of the 88 attempts performed. Analyzing the recovered material together with the updated data of the species, the Network 4.6 program revealed a network containing 19 haplotypes, 4 of them generated only with ancient population samples, which are new for the species. The results are still preliminary and their meanings should be evaluated with caution. However, it should be noted that the four new haplotypes found could support the hypothesis of a higher haplotype diversity in E. australis when it was hunted.