From our work on miniaturised chameleons, we have also found that, as these lizards shrink, their genitals increase in relative size. We think that this is because the females are larger than the males. Because the male genitals must couple with those of the females for successful reproduction, and because the female is not as small as the male, the male’s genitals are constrained to remain proportional to the size of the female, even while his body size evolves to be smaller.
There are hundreds of open questions in the field of tiny vertebrate studies. We are just beginning to understand how widespread and common this trait is, how many species have done it, and how many miniaturised species remain undescribed. There is a whole miniature frontier of interesting research to be had among these tiny vertebrates, and I, for one, am excited to see what we discover next.
Mark D Scherz, Research scientist, Technical University Braunschweig