Notable: Penguin population turnover from ancient DNA

Notable paper: Stefanie Grosser, Nicolas J. Rawlence, Christian N. K. Anderson, Ian W. G. Smith, R. Paul Scofield, Jonathan M. Waters. 2016. Invader or resident? Ancient-DNA reveals rapid species turnover in New Zealand little penguins. Proceedings of the Royal Society B doi:10.1098/rspb.2015.2879

Synopsis: Grosser and colleagues studied mtDNA from ancient remains of two species of little penguins on New Zealand, the New Zealand endemic Eudyptula minor and Eudyptula novaehollandiae, which occurs both in New Zealand and Australia. They found that all of the remains dating to before 1600 represent E. minor, and they conclude that the appearance of E. novaehollandiae happened only after human-mediated decline in the E. minor population, both because of human predation and because of the human introduction of dogs and rats.

Interesting because: Ancient DNA is increasingly useful to determine the causes of population turnover. Prior to this large sample of aDNA, some biologists had speculated (on the basis of comparison of genetic data from living birds) that E. minor and E. novaehollandiae had coexisted in New Zealand for as long as 200,000 years. Retrospective population genetics just isn’t very accurate when it comes to the time of population divergences and demographic parameters. Ancient DNA is vastly better with questions like this one.

Cool figure: I really like the way they have illustrated the haplotype network and changes in frequencies over time:

Figure from Grosser et al showing haplotype network for penguin mtDNA
Figure 2 from Grosser et al. 2016. Original caption: Temporal haplotype network reconstruction of New Zealand (blue) and Australian little penguin (red) mitochondrial control region sequences from southeastern New Zealand (Otago). Each layer represents a particular time period as indicated in the inset. Circle size is proportional to haplotype frequency. Edges between haplotypes represent single mutation steps. Unobserved haplotypes are indicated by small black circles. Grey circles connected by dashed lines represent haplotypes that occur within the population but not the particular temporal layer. The insets show sampling localities in Otago. Circle colour in insets indicates species affiliation of specimens of the particular site. Blue and red borders interpolate Otago-wide distribution of E. minor and E. novaehollandiae, respectively. H, haplotype diversity; n, sample size; NZ, New Zealand (E. minor).