Saturday, 13 December 2014

Bird Genomes, Bird Phylogeny—and Mesites

Science this week (12 December) carries a series of articles and eight papers on a major bird genome project. The  whole genomes of 48 species of have been sequenced by a very large and international group of authors. Using massive computing power they have obtained a new phylogenetic tree that completely destroys some traditional groupings while throwing up or confirming interesting relationships between modern species.

An example of the latter is the close relationship between the mesites—the very peculiar birds endemic to Madagascar—and the sandgrouse, the common ancestor of which, according to the results, split from the doves. In turn, the closest relations of this entire group (Columbimorphae) are  the flamingos and grebes (Phoenicopteromorphae).

Another confirmation of earlier findings on smaller parts of the genomes is that Birds-of-prey—the old Falconiformes—are blown asunder. That other strange bird, the hoatzin that is shown on the cover, emerges as most closely related to the plovers and cranes.

This is the summary of the phylogeny from the paper:

The origins of the work lie in trying to find the genes responsible for vocal learning in birds but the study so far, as I have just touched the surface of, has far wider implications for all that we know about birds. The radiation of modern birds, now grouped as the Neoaves, which occurred from nearly 70 until 50 million years ago, is really only now being revealed.

However, there is still some uncertainty, as might be expected from the number of species in which the genome has been sequenced; where the owls fit in is one example. The genomes of other species are apparently on the way to join the original findings in another round of number crunching.

I cannot resist moving from the general to the particular by showing a photograph—albeit a poor one—of a mesite. The mesites in their appearance and behaviour are some of the strangest birds I have seen; designed by a committee of civil servants doesn’t even start to describe the Brown Mesite (Mesitornis unicolor). We saw all three species in Madagascar in 2003. The commentary that accompanies the papers in Science describes the mesites as flightless. They are not flightless, they can fly but just do not often fly. They live, feed and nest within a hop of the ground. The Subdesert Mesite (Mesitornis benschi) only really flies when it feels threatened. Then it flies up onto the top of a low tree, puts its head down and tail up while fluffing out its breast feathers. For all the world it looks like a fruit. The photograph, a screen grab from a video, shows the bird just coming out of this position, slowly raising its head and lowering its tail before slipping to the ground. It only occurs in a small area of south-west Madagascar in spiny forest. The Moussa family were, and apparently still are, the expert guides in Ifaty. When we were there the forest was being cut back at an alarming rate so it is good to know that at least some of it remains.

Subdesert Mesite, Ifaty, 4 November 2003