Preliminary Genomic And Isotopic Insights From Whaling Era Southern Right Whale Bone From Mainland Aotearoa New Zealand
Natalie dos Remedios, Caitlin Smith, Melinda Allen and Emma L. Carroll
Southern right whales (Eubalaena australis) experienced a dramatic demographic decline due to whaling.<br />Previous global simulations suggest this has decreased mitochondrial DNA (mtDNA) richness by between 32%<br />and 75%. In Aotearoa New Zealand, a single stock assessment suggested a decline from 30,000 prior to whaling<br />to as few as 40 whales in 1920. Despite the population rebounding to approximately 2000 whales in 2009, this<br />decline lasted for approximately five generations, with possible population level consequences for genetic<br />diversity. Here we undertake an analysis of bone samples from historical whaling sites, assumed to represent the<br />mainland New Zealand whaling era population. Combining mtDNA sequencing and stable isotope analyses, we<br />present preliminary analyses comparing these historical samples to the contemporary population. Of 18 whale<br />bone samples analysed, 13 yielded Sanger sequencing data of the mtDNA control region, confirming the presence<br />of 11 southern right whales and two humpback whales. Of the 11 southern right whale sequences, 10 were of high<br />quality and enabled population diversity statistics to be calculated. These 10 sequences included nine haplotypes<br />(217 bp), only one of which has been observed to date in the contemporary New Zealand population (n=692<br />whales). Despite a relatively small sample size, the haplotype and nucleotide diversity of the historical population<br />was substantially greater than that of the contemporary population. In addition, we extracted bone collagen and<br />generated stable isotope data (Î´13C and Î´15N) for four southern right whale samples and one humpback whale.<br />These samples fell to one end of the distribution of contemporary samples but indicated a potential shift in foraging<br />patterns that will only be elucidated through the analysis of additional historical samples. Overall, these<br />preliminary results provide a first glimpse of the genetic diversity once present among past southern right whale<br />populations in New Zealand, and highlight the potential to understand changes in foraging patterns over time<br />through the analysis of data from both historical and contemporary samples.