adapt & dive

Penguin evolution and conservation

Penguins are one of the most dis-tinctive and charismatic bird orders. Supremely adapted for flipper-propelled diving, they are the most aquatic of all birds and hold the records for the deepest and longest dives. A new study by Theresa Cole and a large team of researchers (Nature Communications, doi: 10.1038/ s41467-022-31508-9) provides unprecedented insights into how they adapted to a life at sea.

Thanks to their dense bones and aquatic habitats, penguins are well represented in the fossil record. In addition to the 19 extant species, nearly 50 other penguin species are known from fossil or sub-fossil remains. Cole’s team combined data from fossil species with genomic evidence from all extant and recently extinct penguins to infer their evolutionary history.

By comparing the genomes of penguins with those of other birds, the researchers were able to identify the genes responsible for a suite of marine adaptations. These include genes that enhance dive duration by promoting oxygen storage in the muscles and by improving tolerance to low blood oxygen concentrations. Penguins also have

lost the gene for green cones in their retina and have blue-shifted their colour vision to enhance visual acuity in extremely low light levels.