Researchers used human face recognition techniques to identify and compare
guenons' features
Guenon monkeys' colourful and varied
faces have evolved as a way to avoid crossbreeding, scientists have found.
Many different species of guenons live side-by-side meaning mating with other
species, which could lead to infertile offspring, is a possibility.
The researchers used human facial recognition technology to identify primate
features from photographs. They found that guenons' looks have evolved to become more distinctive from
their relatives living close by.
The findings are reported in the journal Nature Communications and
researchers say they are the best evidence to date of visual signs acting as a
barrier to breeding across species.
Guenons - Cercopithecini - are a group of more than 25 species of
monkeys which originated in the forests of Central and West Africa.
"A key question is what mechanisms keep closely related species that overlap
geographically from interbreeding, so that they are maintained as separate
species.
"Our findings offer evidence for the use of visual signals to help ensure
species recognition: species may evolve to look distinct specifically from the
other species they are at risk of interbreeding with," Dr Higham said.
"In other words, how you end up looking is a function of how those around you
look. With the primates we studied, this has a purpose: to strengthen
reproductive isolation between populations."
Scientists have previously shown examples of species being differentiated
(called character displacement) by acoustic and electric signals but the authors
believe their research is the best example of visual variety across a broad
group.
"These results strongly suggest that the extraordinary appearance of these
monkeys has been due to selection for visual signals that discourage
hybridisation," lead author William Allen said.
"This is perhaps the strongest evidence to date for a role for visual signals
in the key evolutionary processes by which species are formed and maintained,
and it is particularly exciting that we have found it in part of our own
lineage."
The team is now carrying out more research to find out whether guenons are
more distinctive from those species they now live beside or those they were
living with at the time their species emerged.
