Inferring recent historic demographic events (bottlenecks) using genetic data, case study: North Atlantic blue whale (Balaenoptera musculus musculus)

Signals of past demographic changes can be found within the genetic diversity of a population long after an event has occurred. However, modern genetics is not always able to detect past demographic changes. Sometimes, signals of demographic changes are lost over time, overshadowed by other events or statistical power is insufficient to discriminate between different events. In this study we looked at the genetic diversity of the North Atlantic blue whale (Balaenoptera musculus musculus). Blue whales were intensively hunted during the early 1900’s, subjecting the entire species to a bottleneck. We attempted to estimate the timing of this demographic event based upon the current genetic diversity of the population. Additionally, we estimated effective population sizes before and after whaling. Standard bottleneck tests such as the M-ratio test and the heterozygosity-excess were used to see whether a signal of the bottleneck could be detected. MSVAR was used to estimate the timing and the abundances before and after the demographic event based upon genetic data. Finally, BEAST was implemented to look at demographic changes over a longer period of time. Preliminary results suggest other demographic changes distort the signal of the recent bottleneck, shifting the timing of the demographic event