The animals of the Galapagos Islands are renowned for being some of the most unique in the world. With a high number of endemic species, wildlife holidays in Galapagos offer nature lovers a glimpse into a true microcosm of evolution. Many species have adapted to this unique and remote environment by evolving characteristics that enable them to survive the harsh and diverse conditions. Of all the species, though, few have adapted in such an unusual way as the bird that cannot fly. |
The Flightless Cormorant
On his exploration of the archipelago, naturalist Charles Darwin was fascinated by the discovery of a cormorant with wings so disproportionate to the size of its body that it was unable to fly. At the time, Darwin was formulating his groundbreaking theories of evolution and natural selection, and he believed that environmental changes could have resulted in the bird's loss of its ability to fly. In modern studies of the bird's DNA, scientists have discovered that, over two million years ago, it also underwent genetic changes, resulting in the small wings that have rendered it unable to fly.
A Story of Two Halves
While Darwin observed that numerous evolutionary changes occurred in the archipelago that could have contributed to the process of natural selection in the species, scientists have been able to go one step further to decipher the changes in the bird at a molecular level.
Characterised by its short, flimsy wings, this is the largest of all the world's cormorants, and the only one of the 40 species that’s unable to fly. However, it is an extremely strong swimmer, and is able to dive for fish. From his observations of these characteristics, Darwin hypothesized that, with the loss of flight, the bird had developed other skills that enabled it to survive – a process now known as positive selection.
The alternative possibility is that the birds lost their ability to fly simply because they had no predators from which to escape, and they did not need to migrate in order to breed. It's also possible that the changes occurred as a result of a combination of both of these reasons.
Through a project where links were found between the genetic changes in the bird's DNA and changes in the structure of certain proteins in the body, scientists identified the presence of a gene called CUX1. The structure of the gene in the cormorants from the archipelago is different to that of all the other species that are able to fly, leading scientists to conclude that its presence changed the function of certain proteins, thus affecting wing size. They also found that the birds' DNA showed a high number of mutations that affected the cilia, which play a vital role in skeletal development and bone growth.
Research into whether the genetic mutations of the flightless cormorant are shared by other flightless birds is ongoing, but the same kind of genetic changes have been found to cause problems in human skeletal development. The findings from researchers' work with the bird have the potential to lead to new treatments for serious bone disorders in humans.
Encounter the Unique Flightless Cormorant on Wildlife Holidays in Galapagos
For those who visit the region on wildlife holidays in Galapagos, more than 1,000 breeding pairs of the birds can be seen on the islands of Isabela and Fernandina. They can be observed diving for food in the surrounding oceans, using their muscular legs to propel them down into the water. The thriving (and increasing) population is a reminder that, as always, Mother Nature is full of surprises.
Marissa Ellis-Snow is a freelance nature writer with a special interest in the unique wildlife of the Galapagos Islands. Marissa chooses the expert-led led wildlife holidays in Galapagos organised by Naturetrek, which have brought her unforgettable sightings of a wide range of wildlife in one of the most spectacular regions on Earth.
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