Whale Debate Resolved: Settling the Argument Once and for All

After years of debate, researchers have finally resolved the evolutionary origins of the pygmy right whale.

The pygmy right whale (Caperea marginata) is the smallest of the living baleen whales, with a unique tank-like skeleton. Despite its peculiarity, its ecology and behavior are still relatively unknown.

Due to its unusual characteristics, there has been disagreement among scientists regarding the evolutionary relationships of the pygmy right whale. However, a recent study published in Marine Mammal Science aims to settle this debate by sequencing the complete genome of Caperea and combining the findings with morphology and paleontology.

Co-author Dr. Felix Marx, curator of marine mammals at the Museum of New Zealand Te Papa Tongarewa, explains that the skull shape of the pygmy right whale suggests it is adapted for skim-feeding, a feeding behavior where the whale swims at the water’s surface with its mouth open. This behavior is similar to larger true right whales.

Dr. Marx is pleased that the power of genomics has been utilized to shed light on the evolutionary history of the pygmy right whale. The study’s results confirm that Caperea is a distinct lineage and not related to right whales, debunking the long-standing belief that they were closely related.

According to Co-lead author Dr. Kieren Mitchell, genetic information often prompts scientists to reconsider the similarities and differences between species. He suggests that when DNA and anatomy disagree on species relationships, there is usually a deeper and more interesting story about their evolution waiting to be discovered.

Dr. Nic Rawlence, Otago Palaeogenetics Laboratory Director, describes Caperea as a fascinating example of convergent evolution. Despite its resemblance to right whales in terms of feeding strategies, Caperea is likely the last surviving member of an ancient group of whales called cetotheres.

Now that the position of Caperea in the whale family tree has been confirmed, Dr. Ludo Dutoit, co-lead author and researcher at Otago’s Department of Zoology, suggests that further examination of the Caperea lineage and the significant events that influenced its evolution can be conducted.

Dr. Marx adds that Caperea may serve as another example of how unique characteristics contribute to the survival of a lineage. Other examples include river dolphins adapting to freshwater habitats and sperm whales excelling in deep-diving suction feeding.