In Science this week, an international team of researchers reports on the genome sequences of 45 species of birds, creating the most comprehensive avian tree of life to date. The multi-year effort analyzed the genomes of at least one bird from every major bird lineage and, taken together, the findings show how the earliest branches on the avian tree diverged and offer insights into the evolution of avian sex chromosomes, vocal learning in birds and humans, and the evolutionary pressures that led to birds losing their teeth. The results of the effort also point a period of rapid bird evolution in the millions of years that followed the extinction of dinosaurs, and suggest that the earliest common ancestor of land birds such as parrots and hawks was an apex predator. A review article also covers recent progress in tracing bird evolution from theropod dinosaurs, examining research in developmental biology and functional anatomy in the context of the paleontological record to show how key features of birds originated and evolved from their dinosaur forebears. GenomeWeb has more on these bird genome studies here.
Also in Science, a team from the University of Utah provides new details about the ongoing battle between primates and bacteria for nutritional iron, focusing on the iron-binding protein transferrin. While many species of bacteria have developed a molecular receptor capable of taking iron out of transferrin, the researchers say that transferrin in primates has evolved to contain to contain single substitutions to evade bacterial iron-swiping receptors, demonstrating a "central role for nutritional immunity in the persistent evolutionary conflicts between primates and bacterial pathogens."