Fig 5. The size of the naked valley differs between and within species and is dependent on miR-92a expression.

Reduction of miR-92a expression in D. melanogaster T2 legs has led to a derived (d) smaller naked valley in some populations while the ancestral state (a) is thought to be a large naked valley like in other D. melanogaster group species and other species (e.g. D. pseudoobscura). The absence of a naked valley in D. virilis is possibly due to absence of miR-92a expression, while the presence of small naked valleys in other species of the virilis group (e.g. D. americana) could be explained by a gain of microRNA expression. The coloured bars represent the spatial expression of each gene in the femur with lighter orange indicating where sha expression is post-transcriptionally repressed by miR-92a.