morphology

On Pharyngula, PZ Myers considers a computer model which posits that bones are simply exoskeletons turned inside-out. Myers writes “We know from the homology of the patterning molecules involved that vertebrates and invertebrates are upside-down relative to each other, so at some point an ancestor flipped.” Such major differences in body plan arise during embryonic development, driven by highly evolved genetic instruction. But the growth of internal and external skeletons depends on distinct biological mechanisms, leading PZ to call the dataless computer model “abiological and ahistorical…

A recent study by Gabriela Pirk in Insectes Sociaux provides me with an excuse to share this photo: Minor workers of the seed harvester Pheidole spininodis (left) and the predatory Pheidole bergi lock jaws in combat. Jujuy, Argentina. Pirk et al examined the diet of both Pheidole species in the Monte desert of Northern Argentina.  Why would someone spend time doing this?   Ants are important dispersers of seeds, and these Pheidole are two of the most abundant seed-eating ants of the region.  What they do with the seeds, which ones they choose to take, and how far they take them has…