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Passerines, parrots Core landbirds Comparing the genomes of representatives Falcons of almost all bird orders provides better reso- Seriemas lution of the relationships among the major Rollers, kingfishers, hornbills, barbets, lineages in the Neoaves (lower case groups). woodpeckers, trogons, mousebirds, etc. Owls (among oscine passerines, parrots and Vultures, eagles, hawks Core waterbirds hummingbirds). However, there are also Pelicans, cormorants, gannets, some key differences, with unique genes ibises, herons, storks, etc. Passerea associated with song learning in passer- Penguins, albatrosses, petrels ines, and a peculiar ‘song-within-a-song’ Divers system found in parrots, which might ex- Tropicbirds, Sunbittern, Kagu plain their ability to mimic human words. Shorebirds, cranes Still another paper showed how the bird’s Hoatzin sex-determining w-chromosome (which is found in females) has evolved to different Hummingbirds, swifts, nightjars & allies degrees in different lineages, and in some Bustards birds retains many more functional genes Turacos than the y-chromosome in mammals. An-

Cuckoos, coucals Columbea other paper explored the genes that allow Pigeons, sandgrouse, mesites penguins to tolerate extreme Antarctic Flamingos, grebes environments. And a more applied paper GALLOANSERES (gamebirds, ducks, geese) explored genetic diversity in endangered species. Not surprisingly, species such as PALAEOGNATHAE (ratites, tinamous) the Crested Ibis that have experienced re- cent population bottlenecks had reduced The study found that the Neoaves are di- rapid radiations) resulted in plenty of con- diversity in their immune-system genes. the last word on the vided into two groups, dubbed the Colum- flicting gene and species trees. However, genetic diversity was greater peter ryan bea and Passerea. The former comprises Given that the entire genome was avail- than expected, and there was evidence of two main lineages: the pigeons, sandgrouse able for analysis, is this really the last word rapid evolution in metabolic- and brain- and mesites (Columbimorphae), and the on the evolutionary history of birds? Al- function genes, giving some degree of of flamingos and grebes (Phoenicopterimor- most certainly not at a fine scale: adding hope for the long-term viability of such evolution birds phae). The branching sequence among more species is likely to shuffle some of populations. the Passerea was not resolved unequivo- the branches around. However, the broad The studies confirmed that all mod- he Avian Phylogenomics Con- comprises more than one billion base was until now the most comprehensive cally, but core groups of landbirds and structure is likely to remain. Indeed, there ern birds have appreciably smaller, more sortium was established four pairs! assessment of bird evolution. waterbirds were detected, as well as sev- are relatively few changes from the rela- streamlined genomes than mammals, years ago to conduct the first Erich Jarvis and 103 colleagues recently At the largest scale there were no big eral miscellaneous groupings. Perhaps the tionships established by Hackett’s study on thanks to shorter sections of non-coding Tgenomic study across a vertebrate class. published some of the findings of this vast surprises. Modern birds are still divided more surprising groupings included the a much smaller amount of genetic data six DNA and about 10 times fewer contribu- Its goal was to obtain complete gene se- endeavour in the leading journal Science. into three groups: the Palaeognathae Sunbittern (and Kagu) being linked to the years ago. I think it’s safe to say that we now tions from viral genomes. The latter result quences for representatives of all bird They had at their disposal the genomes of (ratites and tinamous), Galloanseres tropicbirds, and the enigmatic Hoatzin as- have a fairly good idea of how and when suggests that birds either are less suscepti- orders. When you consider that the hu- 48 birds from 36 of 40 extant bird orders (gamebirds and waterfowl) and Neoaves sociated with the shorebirds and cranes. modern birds evolved. Adding more spe- ble to viral invasions or are better able to man genome project cost US$3-billion (missing only storks, which are allied to (all other birds). What was new, however, However, these relationships were lost cies is most likely to improve our under- purge viral genes than mammals. With the and lasted 14 years, this might seem an the broader Pelecaniformes, and three rat- was the ability to infer the early origins when a smaller subset of the data was used. standing of where these events took place. notable exception of woodpeckers, all lin- unrealistic goal. But sequencing technol- ite groups: rheas, kiwis and cassowaries- of the Neoaves. This vast group, which The bustards formed an unlikely alliance eages also have many fewer repeat genes, ogy has progressed in leaps and bounds Emu). With such a vast amount of data to comprises more than 10 000 species in with the turacos, cuckoos and nightjars/ arvis’s paper was just one of a suite of which might limit their rate of evolution since the human genome project was work with they had the luxury of using a 33 orders, underwent an explosive ra- swifts/hummingbirds. 23 published jointly as a ‘flock of ge- relative to mammals. Quite why birds have completed in 2003. Today a genome can variety of datasets to infer the evolution- diation around 60‒70 million years ago, Among the core landbirds, the parrots Jnomes’, with eight papers in Science smaller genomes remains open to debate, be sequenced in a matter of months for ary history of birds. What they consider almost certainly associated with the sud- were again found to be sister to the pas- and 15 papers in other journals. One paper but it has been argued that it represents yet around US$100 000. The greatest chal- to be the ‘best’ tree was based on a mere den availability of new niches following serines, together forming a group with the showed that the common ancestor of all another adaptation to flight – with smaller lenge is managing the vast amount of 41.8-million base pairs – less than five the large meteor impact 66 million years falcons and seriemas. The position of the modern birds lost its bony teeth about 116 genomes reducing the mass of each cell! data generated – the average bird genome per cent of the total genome – selected ago that triggered the most recent mass mousebirds and trogons was not fully re- million years ago. Another paper found What is certain is that the raw data gen- because they were comparable gene se- extinction event (and saw the demise of solved, but both fall within the core land- that convergent changes in the activity of erated by the Avian Phylogenomics Con- above Rüppell’s Bustard. The bustards quences across all species sampled. Yet all non-avian dinosaurs). Because the bird group. The results of the ‘best’ tree more than 50 genes are responsible for the sortium – all publicly available – is set to formed an unlikely alliance with the this is more than one thousand times Neoaves radiated so quickly, it has been were broadly supported by analyses based brain structures involved in vocal learning revolutionise our understanding of avian turacos, cuckoos and nightjars/swifts/ more data than was used by Shannon very hard to deduce the sequence in on different subsets of the genome data, in humans and birds, even though song evolution and genetics. hummingbirds. Hackett and colleagues in 2008, in what which they evolved. but incomplete lineage sorting (due to very learning has evolved three times in birds Peter Ryan

10 african birdlife march/april 2015 news & views 11