The process of speciation usually takes an incredibly long time, but for the Galapagos Big Bird, the process happened extremely quickly — in just two generations of finches, to be precise. This new lineage of birds comes from the hybridization of two existing species of finches on the Galapagos archipelago.The finches on Galapagos are an incredibly important part of scientific history, and are an integral part of the method in which Darwin first described the theory of Natural Selection. This explanation for the evolution of biodiversity here on Earth has radically changed the field of Biology and has given us a greater understanding of the world around us.
While participating in field work on the island of Daphne Major in 1981, Princeton University researchers Rosemary and Peter Grant noticed an immigrant male that was larger than the island’s populations with a song that was different than the existing species’. Over 40 years of direct observation, the Grants discovered that the Galapagos Big Bird was the origin of a new lineage after this immigrant male bred with a resident medium ground finch female. Subsequent DNA analysis revealed that this strange male bird was a large cactus finch that had flown to the Galapagos from Española island, more than 60 miles to the southeast.
While any discovery of a new species is exciting in and of itself, the identification of the Galapagos Big Bird lineage is significant because it shakes up our understanding of how speciation works. Previously, it was thought that all incidences of new species took an incredibly long time to develop, but the Grants’ publication in Science shows a new species developing in just 40 years.
In most cases, different species do not mate with one another, but in recent years there have been a number of cases where two closely related species have successfully mated and produced offspring with hybridized DNA. The Galapagos finches are especially significant because there’s a large amount of gene flow between the 18 species on the island, which leads to situations like the evolution of the Galapagos Big Bird.
The discovery of this brand new lineage is a testament to the usefulness of long-term field studies. While it’s impossible in most cases for a single researcher to observe the development of a species from beginning to end, we now understand that speciation might not take nearly as long as we think. When two related species mate, it’s a real possibility that we could see a brand new animal like the Big Bird within tens of years rather than hundreds.