June 19, 2018 by Hayley
Dunning, Imperial
College London
Extensive new datasets about the
world's birds are helping to solve the riddle of how life on Earth diversified.
By combining global datasets on
bird characteristics, citizen-science species sightings and genetics,
researchers have begun to answer some key questions in biodiversity. The
results are published today in Nature Ecology & Evolution, in two
parallel studies that include Imperial College London researchers.
The first paper compiles body
measurements and estimates of evolutionary history for hundreds of closely
related bird species (called 'sister species') to study how new species evolve.
In most cases, new bird species
begin to emerge when one population is isolated geographically from others,
such as by a mountain range. Later, the diverging species may extend their
geographical ranges, bringing them back into contact.
These encounters can play out in
one of three ways: the species can interbreed and form a single species again;
they can stay separated but with hard borders between their two ranges; or they
can continue to expand their ranges until they coexist over a wide area.
What determines whether emerging
species stay separate or coexist? The team, led by Dr. Jay McEntee at the
University of Florida, used a vast citizen-science database of bird sightings
worldwide to identify where sister species were seen in the same place at the
same time, allowing the timing and extent of coexistence among sister species
to be estimated.
Different traits allow
coexistence
The researchers found that if
sister species had very different traits that affect their way of life, such as
beaks adapted to different foods, they were more likely to coexist sooner and
over larger areas.
In contrast, those with very
similar traits appeared not to overlap successfully. The researchers think this
is because there is 'interference' between the species, such as interbreeding,
or competition for resources like food.
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