Venom gland size and venom complexity – essential trophic adaptations of venomous predators: a case study using spiders

Specialised predators possess variety of adaptations. In the venomous predators this may include size of the venom gland and venom composition. It is expected that due to different foraging strategies predators with a wide trophic niche (generalists) should possess larger venom glands that contain more diversified components than species with a narrow niche (specialists). We focused on spiders, as the most diversified group of venomous predators, in which a wide variety of trophic strategies has evolved. We conducted a comparative analysis using 40 spider species, in which we measured the size of their venom gland and its complexity using proteome profiling methods. The species were classified into three trophic groups: generalists, facultative specialists, and obligatory specialists. We found that the venom glands of generalists are larger than those of obligatory specialists, which is presumably due to more frequent prey capture by the former. The complexity of venom, of peptides (2-1...