The Australian National
University
The number of songbird species is much
larger than the number of other bird orders, but until now scientists have
not been sure why.
DNA mutation rates are the deciding
factor in the battle of the birds, which sees songbird species
disproportionately outnumbering other bird orders, according to research
from The Australian National University.
Researchers have long wondered why some groups of organisms boast more
species than others. Work carried out in the ANU College of Medicine,
Biology and Environment sheds light on this problem. The research reveals
that diversification in bird species is directly linked to the rate of
genome evolution, that is, how quickly changes in DNA occur.
Dr Robert Lanfear from the Research School of Biology, who led the
research team, said that the study?s results confirm that when a bird
species is split into two separate populations by a physical barrier, such
as a mountain range, the rate at which the two populations diverge to
become separate species depends on the mutation rate.
?It has been shown before that species that accumulate more changes in
their DNA tend to diversify more quickly. But is it changes in the DNA
that cause speciation, or speciation that causes changes in the DNA? Our
study suggests that, at least for birds, it?s the changes in DNA that
cause speciation,? he said.
?From an evolutionary perspective, this takes us one step closer to
understanding why some groups of organisms have more species than others,?
said Dr Lanfear.
?Our research has shown that part of the answer to this mystery may be
because lineages with faster mutation rates, such as songbirds, diversify
more quickly.?
The paper, ?Mutation rate is linked to diversification in birds? is
published in the current issue of the Proceedings of the National
Academy of Sciences. | 