Off the coast of Ecuador, there is a cluster of volcanic islands that seem like they are on another planet. These islands, called the Galapagos, have been untouched until very recently, being used as a base for 18th and 19th century sailors and pirates, and finally being claimed and settled in 1832.
These islands are home to a host of strange creatures that are monumentally different from their mainland counterparts. One well-known species is the flightless cormorant (Phalacrocorax harrisi), which seems to have traded flight for swimming skills.
It’s once broad wings are now short and stubby, 3 times smaller than what it need to fly. For reference, it’s the size of a normal cormorant, but with the wingspan of a Steller’s Jay. How did its wings get so small in the first place?
Faulty genes are thought for be blamed. The CUX1 gene, in a defective form, is known to cause smaller wings in chickens. This shows that the flightless cormorant’s different form of CUX1 may also cause the same changes. Little cell antennae called primary cilia that receive important developmental messages were broken, like an old TV that won’t give you the latest news. You go on living, but don’t know what’s new.
Galápagos cormorants have had continually smaller wings over the past 2 million years. The have exceptional diving skills compared to other cormorants. The CUX1 gene mutated, and natural selection determined that better swimmers get more food, spreading the gene and shrinking the wings. Lack of predators diminished liabilities of flightlessness, and over time, they came to look as they are today.
*A quick side note: They don’t fly, but they still hold their wings out to dry. It seems unnecessary. That’s okay, though, because they look funny, like a T. rex trying to show you how wide something is.*
It’s an amazing world of science out there… let’s go exploring!