Data from: 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 (2-15 kDa) and
proteins (15-250 kDa), was more diverse in generalists than in
specialists. Multivariate analysis of venom revealed significant
differences among the three trophic categories only in the complexity of
peptides. Our study thus shows that venom gland size and its content have
taken different pathways during the evolution of trophic strategies in
spiders. Generalists evolved larger venom glands with more complex
composition, whereas obligatory specialists possess smaller glands with
less diverse chemical structures, presumably containing prey-specific
toxins.