Darwin and the Floreana Mockingbird
When Charles Darwin visited the island of Floreana in 1835, he collected specimens of the Floreana Mockingbird. These specimens later ended up at the Natural History Museum in London. Today, DNA from these birds are helping conservationists make important decisions about the future of the species.
Since Darwin’s visit to the island, the Floreana Mockingbird has been driven almost to extinction. There are just 500 birds left in two sub-populations on two small islands off the coast of Floreana named Champion and Gardner-by-Floreana. The bird is no longer found on the island of Floreana because of rats and dogs introduced to the island from Darwin’s vessel.
Conservationists want to reintroduce the mockingbird to Floreana, but had questions about the bird populations on the other two islands.
From the BBC:
For this reintroduction to be effective, Dr James said, a population would have to be restored that was “as close as possible to what existed before”.
DNA samples that were taken from the birds on the two islands in 2006-2008 and 1905-1906 were compared to DNA samples from the specimens Darwin collected. Scientists discovered that the birds on both Champion and Gardner-by-Floreana have a similar genetic makeup to Darwin’s specimens. Further investigation revealed that these two sub-populations split and began evolving independently, possibly around the time of Darwin’s visit.
The birds on Champion show high levels of in-breeding, so conservationists have concluded that birds from both of these two sub-populations should be used to establish a single, mixed population on Floreana. More genetic diversity in the species will ensure a healthy re-introduction. Therefore the new birds on Floreana should be very similar to the birds originally seen by Darwin.
Dr Karen James, genetics expert at the Natural History Museum said: ‘Though Darwin knew nothing of DNA, the specimens he and FitzRoy collected have, after 170 years of safe-keeping in collections, yielded genetic clues to suggest a path for conservation of this critically endangered and historically important species.’