New Scientist - 31 May 2014.bak

IN BRIEF
THEO ALLOFS/MINDEN
Big flightless birds get a
shake up of their family tree
HUGE flightless birds like emus and the extinct moa may
look alike, but an analysis of ancient DNA reveals they are
more distantly related than we expected.
Moas, which lived in New Zealand, and emus belong to
a flightless group called ratites. Until now the assumption
was that early ratites spread around the world on foot
while Africa, New Zealand and Australia were one
land mass. When this broke up, the birds were separated
and evolved independently, producing everything from
Madagascar’s huge extinct elephant birds to the smallest
ratite, New Zealand’s kiwis.
Planet-munching suns are messy eaters
HUNGRY suns are unlikely to
be good hosts. Sun-like stars
sometimes devour their Earth-like
planets, and astronomers have
figured out how to identify the
grizzly leftovers.
Stars are mostly made of
hydrogen and helium, but they
can also contain a spattering of
other elements on their surfaces.
Analysing starlight lets scientists
see which elements are present.
Keivan Stassun at Vanderbilt
University in Nashville,
Tennessee, and his colleagues
used telescopes in Chile to look
at the light from a pair of sun-like
stars (The Astrophysical Journal,
doi.org/sv8). Both stars host
relatively large planets, with
masses between those of Neptune
and Jupiter. The team analysed
15 elements, including known
building blocks of rocky worlds.
But their DNA begs to differ. Alan Cooper of the
University of Adelaide in Australia sequenced DNA from
the bones of Madagascan elephant birds, and compared
it with that of other flightless birds. This showed that
elephant birds and moas are not evolutionary siblings at
all, but evolved separately from small flying birds. And
while Madagascar’s elephant birds are indeed closely
related to New Zealand’s kiwis, their last common
ancestor lived much more recently than 100 million years
ago, which is when Madagascar and New Zealand split
apart. This implies that they must have descended from
a bird capable of flying across the oceans.
Moas were most closely related to South American
flying birds called tinamous, which also supports the idea
that it evolved from a flying bird (Science, doi.org/swq).
They found that both stars had
much higher levels of Earth-like
components than our sun,
suggesting that these stars ate
rocky planets that once orbited
alongside the existing gas giants.
Finding stars that show signs
of planet-eating can speed up the
hunt for habitable worlds, because
systems that are unlikely to host
life can be quickly ruled out. “The
one that looks like it swallowed its
Earth already is probably not the
one to start with,” says Stassun.
Unique ‘potter’ frog
packs eggs in mud
A NEWLY discovered frog is the
only amphibian that coats its eggs
in mud. Doing so might protect
the eggs, but beyond that it may
also pay the frogs to be different.
The kumbara night frog lives in
south India. Kotambylu Vasudeva
Gururaja of the Indian Institute of
Science in Bangalore, who found
it, saw them pick up mud with
their forelimbs and spread it on
their eggs (Zootaxa, doi.org/sv6).
They might do it to stop the
eggs drying out, says Gururaja,
or to hide them from predators.
But he thinks the real reason is
that the frogs simply need to be
different from their neighbours.
Two related species, Jog’s night
frog and Rao’s dwarf wrinkled
frog, share the area. So each
species needs to differentiate
itself with distinct behaviours
to avoid futile interbreeding.
Gururaja found that they all make
unique calls, mate differently and
care for their young differently.
Fix leaky gut lining
to slow HIV’s attack
PLUG the gut to stall HIV.
It seems the virus damages the
gut, allowing bacteria to leak out
and spark an immune response,
triggering many lethal diseases.
Ivona Pandrea at the University
of Pittsburgh and colleagues gave
a drug used to treat kidney disease,
called sevelamer, to monkeys
newly infected with the simian
equivalent of HIV. The drug binds
to bacteria, keeping them safely
inside the gut. Those given the
drug had a dramatically reduced
immune response compared with
a control group (Journal of Clinical
Investigation, doi.org/swc).
Because an increased immune
response triggers many lethal
diseases in people with HIV, giving
the drug to people soon after
infection may prolong lives.
18 | NewScientist | 31 May 2014