Evolutionary insights from the genome of the Galápagos finch provide a fitting birthday present for Charles Darwin
Today is International Darwin Day, a celebration held in honour of Charles Darwin’s birthday on February 12th, 1809. This provides a very special opportunity to acknowledge Darwin’s enormous contribution to our understanding of the evolutionary origin of species, and today we are delighted to be able to bring you some genomic insights into one of the most iconic species in evolutionary biology.
Darwin first formulated his ideas on natural selection following his work as resident naturalist on HMS Beagle, a hydrographic survey ship bound for South America in the 1830’s. Of all the samples of flora and fauna collected by the young Darwin during this voyage, perhaps the most famous to make it into the annals of history are his collection of finches from various islands of the Galápagos archipelago.
Darwin was struck by the enormous variation in different types of beaks seen in these birds, that appeared to be tightly linked to very specialised feeding behaviours: some had slender beaks for eating insects; some had robust beaks for cracking nuts.
Although Darwin was to later see this pattern of specialisation in many other taxa in his extensive collection, few examples were to show this radiation so clearly, and to capture the essence of his nascent theory so well as among the finches.
“The most curious fact is the perfect gradation in the size of the beaks in the different species of Geospiza, from one as large as that of a hawfinch to that of a chaffinch, and… even to that of a warbler…” Charles Darwin, The Voyage of the Beagle 1839
To continue the celebrations of Darwin’s 204th birthday, BMC Genomics is delighted to be able to publish an article describing ‘Insights into the evolution of Darwin’s finches from comparative analysis of the Geospiza magnirostris genome sequence’
Here, an international collaboration of authors from the US and UK report an evolutionary analysis of the genome of the large ground finch (Geospiza magnirostris), one of 14 closely related species of Galápagos finch, and characterised by its large, nut-cracking beak. By assembling a draft genome of this species –the first of any of this group of iconic birds– the authors were able to gain unprecedented insight into the adaptive radiation of these finches that occurred some 2-3 million years ago, following their first arrival on the islands when much of the archipelago was still being formed.
This sequencing effort was able to predict over 13, 000 protein-coding genes from the Geospiza magnirostris genome assembly, of nearly a billion individually sequenced bases. Of these, the researchers were able to predict that 21 genes had been subject to positive selection in the Darwin’s finch lineage, including two genes that can be implicated in influencing changes in beak morphology. This work therefore presents the first fledging of a research effort that the authors hope will ”provide the necessary foundation upon which to build population genomics resources that will shed light on more contemporaneous adaptive and non-adaptive processes that have contributed to the evolution of the Darwin’s finches.”
We can only imagine the delight that Charles Darwin might feel to discover echoes of selection in the genomes of his most iconic namesake species. What a lovely birthday gift.
See more on the authors’ website ‘Nice timing: Our paper on the Darwin’s Finch genome is out today on Darwin’s birthday’
Simon Harold and Catherine Rice. Executive Editors, BMC Series