Relationships between genome size and intertegular span (a) and head width (b) in Melipona species with low (◦) and high (•) heterochromatin content. (a) Intertegular span (r = –0.0123 and r = 0.0409, for species with low and high heterochromatin content, respectively). (b) Head width (r = –0.246 and r = –0.0275, for species with low and high heterochromatin content, respectively). The numbers 1–17 are the same as in Table I.