In the last few years, there has been a lot of work (finally!) on how the size of developing organs is controlled. An animal has to have the correct proportions, so every organ needs to coordinate with every other organs and decide how fast to grow and when to stop growing. Several pathways have been shown to be required for this coordination. Now, this paper shows that one of the ways growth is coordinated is through the regulation of tRNA synthesis:
Drosophila RNA polymerase III repressor Maf1 controls body size and developmental timing by modulating tRNAiMet synthesis and systemic insulin signaling
How is this relevant to evolution? Body size and organ proportions (allometry) are among the fastest evolving morphological traits, but we know virtually nothing about how that happens. Similarly, sexual size dimorphism is very common, but we don’t know how it is accomplished and how in changes in evolution. Hopefully, better knowledge of the molecular genetics of size control will stimulate more work on the evolution of size and allometry.