8 July 2013
African starlings evolve color faster than any other bird — 10 times faster than their ancestors and modern relatives according to a new study from the University of Akron.
Like other Sturnidae these birds had iridescent qualities, but after they made it to sub-Saharan Africa 17 million years ago their colors went wild. The cells that give their feathers iridescence are called melanosomes. Instead of the usual simple rod-like forms, glossy starlings (Lamprotornis) developed hollow rods, solid flattened rods, and hollow flattened rods. Though these divergent melanosomes are sometimes found in other birds, glossy starlings can have all the variations in one species. This produced an explosion of new colors.
At the University of Akron Rafael Maia studied microscopic feather structures and used spectral color analysis and evolutionary modelling to figure out how these starlings evolved four types of melanosomes and 19+ species. It happened very fast.
Their social structure helped. For glossy starlings, color confers high rank in both sexes so the most colorful birds are the most successful breeders. Intense social pressure selected for better and better colors.
The results are gorgeous. Above, a greater blue-eared starling (Lamprotornis chalybaeus) shows off his teal and blue back. Below, a lesser blue-eared starling (Lamprotornis chloropterus) displays five colors even though he’s molting.
Read more about the study here in Science Daily.
(photos of a greater blue-eared and lesser blue-eared starling from Wikimedia Commons. Click on the images to see the originals)