Penguin Genomes Unveiled

Today, the Penguin Genome Consortium announced that they have completed genomes of all living penguin species. This international team includes research form about a dozen countries specializing in all aspects of penguin research and conservation.  Project leaders Hailin Pan, Tess Cole, and Guojie Zhang invited me to contribute a fossil perspective to the paper, joining the team of 48 researchers from ten different countries who came together to complete this monumental task.

Genetic datasets can help biologists understand how species are related to one another, and how they evolved.  When I started working on penguin evolution about 15 years ago, we only had data from 5 genes for penguins, providing DNA sequences that totaled a few thousand base pairs in length.  The datasets were so small, I remember aligning the sequences by eye on my laptop. The complete genomes are around 1.3 BILLION base pairs long. Capturing datasets this hug were unimaginable a short time ago, but thanks to the relentless advancing of technology it is now not only feasible but affordable. It cost an estimated $300,000,000 dollars to sequence the first human genome, which was completed in 2003. Today, the cost to sequence a human genome is approximately $1000.

Still, analyzing datasets with billions of base pairs is a daunting endeavor. Fortunately, computer algorithms have advanced to the point where it is manageable. The team has already completed an evolutionary tree of penguins using this massive dataset, which resolves the debate over whether the Aptenodytes penguins (Kings and Emperors) are the first lineage to branch off. That turns out to be the case, meaning the biggest and most cold-adapted of the living penguins split off from the rest very early in modern penguin history (but still later than some the oddballs front he fossil record which left no living descendants).

Evolutionary tree of modern penguins based on new genomes. Figure from Pan et al. 2019.

Over the coming months, the team will use the genomes to explore what makes a penguin a penguin. All sorts of interesting analyses can be conducted with data on this scale, ranging from studies of demography (estimating the history of population sizes over time) to testing boundaries between species to understanding how things like specialized respiratory systems and scale-like feathers evolved in penguins. Understanding the history of penguins is critical because they are among the groups most highly sensitive to climate change. Several species of penguins are already declining or are predicted to decline under future climate change scenarios. It will be exciting times ahead!

Reference:

Pan et al. High-coverage genomes to elucidate the evolution of penguins. 2019. GigaSciencedoi: http://dx.doi.org/10.1093/gigascience/giz117