Year in review: Insect, bird evolution revisited
Genetic analyses produce new family trees
RETHINKING LINKS Insects got an entirely new family tree after an extensive genetic analysis rearranged the creatures' relations.
Dr. Oliver Niehuis, ZFMK, Bonn
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Biologists in 2014 saw what an astronomical amount of data could do for evolutionary questions — and what it couldn’t.
Bernhard Misof of the Zoological Research Museum Alexander Koenig in Bonn, Germany, and 100 coauthors, published an evolutionary family tree of insects and close relatives based on the subset of some 1,478 genes shared by 144 kinds of organisms (SN: 12/13/14, p. 8).
This project, called 1KITE (for 1,000 Insect Transcriptome Evolution), arranged branches on the new tree in ways that looked familiar, but details of certain insect orders differed. Project coleader Karl Kjer of Rutgers University says he has abandoned some of his earlier ideas on branches near the base of the tree as a result of the findings. And Kevin Johnson of the Illinois Natural History Survey in Champaign is rethinking whether the parasitic lifestyle really did evolve twice in Psocodea louse history, as he and colleagues had proposed.
Louse history still poses questions. The new tree puts the origins of parasitic lice at about 53 million years ago, well after dinosaurs died out. Vincent Smith of the Natural History Museum in London, who has proposed that lice nipped dinosaurs, points out that the new study still has considerable uncertainty in its time estimates for louse ancestors.
Another ambitious project redrew the bird genealogical tree based on the full genomes for 48 bird species. Published in December, this work, like the insect family tree, received funding from the Chinese genetic institute BGI.
NEW INSECT TIMELINE
The earliest insects may have arisen as long ago as 479 million years, says a new study. Insects first took flight about 406 million years ago, as plants developed their vascular plumbing and expanded into the air too. Silhouettes show when ancestors of some major living orders of insects likely first started on their distinctive evolutionary paths. (From earliest, on left: springtails; jumping bristletails; silverfish; dragonflies and damselflies; crickets and katydids; bugs, cicadas and plant lice; snakeflies; beetles; sawflies, wasps bees and ants; moths and butterflies; true flies; caddisflies; cockroaches; and scorpionflies.)
Credit: 1KITE, adapted by M. Atarod
