Here is a new study of how bugs are using gene duplications:
Butterflies that have a duplicate gene allowing them to see
ultraviolet colors also have UV-yellow pigment on their wings.
Positive selection of a duplicated UV-sensitive visual pigment
coincides with wing pigment evolution in Heliconius butterflies.
Adriana Briscoe, Seth Bybee and colleagues. doi:10.1073/pnas.0910085107
We now find that Heliconius erato has a second UV opsin mRNA
(UVRh2)âa previously undescribed duplication of this gene among
Lepidoptera. ... Along with the additional UV opsin, Heliconius
have also evolved 3-hydroxy-DL-kynurenine (3-OHK)-based yellow
wing pigments not found in close relatives ... Functional
diversification of the UV-sensitive visual pigments may help
explain why the yellow wing pigments of Heliconius are so
colorful in the UV range compared to the yellow pigments of close
relatives lacking the UV opsin duplicate.
Daphnia and Aphid have lots of gene duplications. The best
general explanation we've found for Daphnia is these are often
functionally diversified, even when newly duplicated. It would
be useful to find better ways to study evolution in co-regulated
groups of genes, and see where duplication fits in. Do gene
duplications offer a cost-effective way to adapt to
environments, or differentiate into ecological niches?