Data from: Evolution of eye morphology and rhodopsin expression in the Drosophila melanogaster species subgroup

A striking diversity of compound eye size and shape has evolved among
insects. The number of ommatidia and their size are major determinants of
the visual sensitivity and acuity of the compound eye. Each ommatidium is
composed of eight photoreceptor cells that facilitate the discrimination
of different colours via the expression of various light sensitive
Rhodopsin proteins. It follows that variation in eye size, shape, and
opsin composition is likely to directly influence vision. We analyzed
variation in these three traits in D. melanogaster, D. simulans and D.
mauritiana. We show that D. mauritiana generally has larger eyes than its
sibling species, which is due to a combination of larger ommatidia and
more ommatidia. In addition, intra- and inter-specific differences in eye
size among D. simulans and D. melanogaster strains are mainly caused by
variation in ommatidia number. By applying a geometric morphometrics
approach to assess whether the formation of larger eyes influences other
parts of the head capsule, we found that an increase in eye size is
associated with a reduction in the adjacent face cuticle. Our shape
analysis also demonstrates that D. mauritiana eyes are specifically
enlarged in the dorsal region. Intriguingly, this dorsal enlargement is
associated with enhanced expression of rhodopsin 3 in D. mauritiana. In
summary, our data suggests that the morphology and functional properties
of the compound eyes vary considerably within and among these closely
related Drosophila species and may be part of coordinated morphological
changes affecting the head capsule.