Convergent evolution is one of the patterns that we see in biology that argues that evolution is much more of a constrained process than sometimes recognized.
"Despite appearances, Hawaii's five species of recently extinct songbirds known as honeyeaters bore no close relationship at all to the honeyeaters found in Australia and New Guinea, according to a genetic analysis reported online on December 11th in Current Biology, a Cell Press publication. Rather, similarities in the way the two groups of birds act and look – including their long bills and brush-tipped tongues specially adapted for gathering nectar – arose independently in the two geographical regions.
The unexpected discovery makes the two groups of honeyeaters a particularly striking example of convergent evolution, the researchers said. Indeed, the Hawaiian honeyeaters include three distinct "morphotypes," each of which is also represented by honeyeaters of Australasia. Convergent evolution refers to the evolution of similar traits in distantly related taxa as a result of common selective pressures imposed by their environments."
