DOI: 10.5061/dryad.sq2g4
title: Data from: Changes in predator exposure, but not diet induce phenotypic plasticity in scorpion venom

description: Animals embedded between trophic levels must simultaneously balance
 pressures to deter predators and acquire resources. Venomous animals may
 use venom toxins to mediate both pressures, and thus changes in this
 balance may alter the composition of venoms. Basic theory suggests that
 greater exposure to a predator should induce a larger proportion of
 defensive venom components relative to offensive venom components, while
 increases in arms races with prey will elicit the reverse. Alternatively,
 reducing the need for venom expenditure for food acquisition, for example
 because of an increase in scavenging, may reduce the production of
 offensive venom components. Here, we investigated changes in scorpion
 venom composition using a mesocosm experiment where we manipulated
 scorpions' exposure to a surrogate vertebrate predator and live and
 dead prey. After six weeks, scorpions exposed to surrogate predators
 exhibited significantly different venom chemistry compared with naive
 scorpions. This change included a relative increase in some compounds
 toxic to vertebrate cells and a relative decrease in some compounds
 effective against their invertebrate prey. Our findings provide, to our
 knowledge, the first evidence for adaptive plasticity in venom
 composition. These changes in venom composition may increase the stability
 of food webs involving venomous animals.
description: First milking
 dataFPLC absorbance
 time-series output for the initial (before treatments, t=0) venom
 extraction. Each of the four treatments are presented on separate sheets.
 Each column is a different scorpion, values are absorbance at 280nm. The
 leftmost column specifies the volume eluted in mL (beginning at 5mL due to
 an initial 5 mL to prime the equipment).Second milking
 dataFPLC absorbance
 time-series output for the second (after completion of treatments, t=1)
 venom extraction. Each of the four treatments are presented on separate
 sheets. Each column is a different scorpion, values are absorbance at
 280nm. The leftmost column specifies the volume eluted in mL (beginning at
 5mL due to an initial 5 mL to prime the equipment).Third milking
 dataFPLC absorbance
 time-series output for the third (3 weeks after the second venom
 extraction, t=2) venom extraction. Each of the four treatments are
 presented on separate sheets. Each column is a different scorpion, values
 are absorbance at 280nm. The leftmost column specifies the volume eluted
 in mL (beginning at 5mL due to an initial 5 mL to prime the
 equipment).xCELLigence output for
 vertebrate cell assaysRaw xCELLigence output
 measuring changes to cell index in response to each venom fraction and the
 whole venom mixture (20 µL). Cell response is a combination measure of
 changes in media conductivity or cell contact/toxicity, which varies as
 the cells deform in response to exposure to a chemical sample. The maximum
 drop value in 2 hours after venom addition was deemed the predator cell
 response. Each fraction was replicated with 3 cell
 wells.Cricket bioassay
 resultsCaption: Results of
 invertebrate toxicity assays, evaluating toxin activity using the righting
 response of immature crickets to each venom fraction. 3 µL of one of the
 14 chemical fractions was injected ventrally into the pronotum of an
 immature cricket, which was then rolled onto its back every 10 seconds 18
 times for a total of 3 minutes. A compromised righting response was
 recorded when a cricket was unable to right itself within 60 seconds of
 being rolled onto its dorsal side. Each fraction was replicated with 10
 crickets.