This post was originally published on February 15, 2009.
Check out the animation I created about my post. Enjoy!
On two small islands somewhere in the midst of the Galapagos Archipelago live some 100-200 mockingbirds. These specific mockingbirds however are some of the rarest bird species in the world, and the story that comes with them is so grand that while I type right now, I still don’t have a title. Let’s take a trip back in time.
In September of 1835, the ship HMS Beagle arrived in the Galapagos Islands. Aboard this ship was a naturalist named Charles Darwin, and little did he know that while investigating this wondrous miniature world, he would start to form some of the most fundamental ideas in the history of science. It all starts with the Mockingbird. Darwin had encountered other mockingbirds on his travels through South America, but being the brilliant observer he was, something stood out to him while he visited the different islands. While on his travels through all of South America, the mockingbirds he found were mostly similar, but among the islands, the mockingbirds had very definite differences in size, beak, plumage, etc. He realized he was seeing more variation between Mockingbird species just miles apart than he had across the span of a whole continent. This got Darwin thinking.
“I have specimens from 4 of the major islands, in each island each kind is exclusively found, the habits of all are indistinguishable, when I see these islands in sight of each other and possessed of but a scanty stock of animals, tenanted by these birds but slightly differing in structure and filling the same place in nature I must suspect they are only varieties … if there is the slightest foundation for these remarks, the zoology of these archipelagos will be well worth examining, for such facts would undermine the stability of species”- C. Darwin
Basically, this is when his light-bulb flipped on, but it gets better. Today these very same birds are extremely endangered, and have vanished from from the island they used to inhabit, surviving on two small neighboring islets. The specific reason is somewhat hazy, but unfortunately, humans probably had something to do with it. At any rate, a conservation effort has been launched to re-introduce the mockingbirds to the island, and this is where it gets really cool. While among the islands Darwin collected four of these birds, each one different, and from a different island. Those very birds Darwin himself brought back over 150 years ago have had DNA samples taken from them to compare to the current surviving birds. By doing this scientists can see which birds today have DNA most similar to the mockingbirds back then, and use those birds for re-introducing as they would be best suited for the islands. The other awesome thing is that by looking at bird candidates, birds can be chosen who have the large gene variation as well. The idea behind this is to give them a jump start on adapting to their environment, since the individual with the best traits will survive, having more variation among individuals, helpful traits are more likely to turn up and help the species survive.
Dr. Karen James of the Natural History Museum sums it up saying “We’re hoping to use the genetic profiles from the old specimens to help us select birds from the surviving populations to introduce to the old island.” Quite frankly, thank you Darwin, yet again.
You can view a video about this here.
After finishing my initial post, I contacted Dr. Karen James herself to see if she could answer some questions.
Q: Do you know if scientists used this method of “selecting the best” individuals in other conservation efforts?
A: Most of the time they use these methods to monitor populations that have already been reintroduced; our project is one of the very few that proposes to use the method before the reintroduction, to select which birds should be reintroduced in the first place.
Q: it seems like it would be a more effective way to “re-grow” a species, or more successful anyway.
A: That’s the idea!
-Happy Darwin Day to you and your class
The natural History Museum at London is a highly regarded institution with a vast collection of specimens, and one of the biggest collections of historical scientific artwork in the world. It is definitely a good source to anyone who is interested.
Are there any other species this method could be used for? How was the role Darwin’s Finches played in his thoughts on evolution different?