April 01, 2008 -- New Haven, Conn. - Higher organisms do not have a "cost of complexity"
- or slowdown in the evolution of complex traits - according to a
report by researchers at Yale and Washington University in Nature.
have long puzzled over the relationship between evolution of complex
traits and the randomness of mutations in genes. Some have proposed
that a "cost of complexity" makes it more difficult to evolve a
complicated trait by random mutations, because effects of beneficial
mutations are diluted.
"While a mutation in a single gene can have effects on multiple traits,
even as diverse as the structures of brain, kneecap and genitalia, we
wondered how often random mutation would affect many traits" said lead
author Gunter Wagner, professor and chair of ecology and evolutionary
biology at Yale. The phenomenon wherein mutation in a single gene can
have effects on multiple traits is known as pleiotropy.
study showed that most mutations only do affect few traits. Further,
the effect of an individual mutation is not dampened because of its
effects on other traits.
Observing 70 skeletal characteristics
in the mouse, the researchers identified total of 102 genomic regions
that affect the skeleton. They concluded that substitution in each
genome segment affected a relatively small subset of characteristics
and that the effect on each characteristic increased with the total
number of traits affected.
"You wouldn't expect to make a lot of
random adjustments - at the same time - to tune up a car," said Wagner.
"Similarly, it appears that tuning up a complex trait in a living
organism is well coordinated and the effects of pleiotropy are more
focused than we thought."
Source : Yale University