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Impacts of caudal autotomy on personality

Citation

Michelangeli, Marcus et al. (2019), Impacts of caudal autotomy on personality, Dryad, Dataset, https://doi.org/10.25338/B80K70

Abstract

Caudal autotomy, the voluntary shedding of a tail, is a last-ditch strategy used by many lizard species to escape from predators. There are several costs associated with caudal autotomy that may cause lizards to make behavioral adjustments during tail regeneration. These behavioral changes may be dependent upon individual differences in response to autotomy (e.g. trait or state-dependent differences) and/or the degree of tail loss, as many lizards have the capacity to only partially shed their tail which likely entails fewer costs relative to complete autotomy. However, no study, to our knowledge, has considered how caudal autotomy, or the extent of autotomy, affects individual behavioural variation. Accordingly, we investigated the effects of both partial and complete tail loss on individual behavioural variation in delicate skinks, Lampropholis delicata. We found that lizards which experienced complete tail loss, on average, became less active, explorative and had much slower sprint speeds following autotomy. These lizards also became more predictable and consistent in their behaviour post-autotomy, exhibiting a notable decrease in their within-individual behavioural variance. In contrast, we did not see any significant behavioural effects in lizards which experienced partial tail loss. We also found a positive among-individual correlation between activity/exploration and neophilia, but tail loss had no effect on the structure of this syndrome. Our results suggest that complete tail loss may impose effects on traits more closely associated with locomotion and predator escape ability, whilst also constraining an individual’s capacity for differential behavioural expression.

Methods

Skinks were randomly assigned to one of three treatment groups: no tail loss (i.e. control, n = 18), partial tail loss (n = 19) and complete tail loss (n = 19). Before tail loss treatments were applied, we first tested each individual through a series of behavioural assays to examine variation and correlation amongst four traits: activity/exploration, sociability, neophilia and sprint speed. To assess behavioural repeatability, we tested individuals in each behavioural assay twice, with each re-test occurring one-week apart to examine short-term repeatability. Once the pre-treatment assays were completed, skinks in the ‘partial’ and ‘complete’ tail loss groups underwent intravertebral tail autotomy. Specifically, caudal autotomy was stimulated by pinching the tail with fine forceps (sensu Cromie & Chapple 2012). Complete tail loss equated to the removal of a full tail, where lizards had their tails removed at approximately 10 mm posterior to the base of the tail. Partial tail loss involved skinks experiencing a break half-way (~ 5 mm from the tip of the tail) along the length of the tail from the tail’s base. Control lizards retained their full-length tail but experienced a similar handling procedure to control for potential behavioural changes brought about by handling stress alone. One week after the tail loss treatment was applied, skinks were again tested twice for each behavioural assay. 

Usage Notes

CSV file headings

SKINK_ID - individual ID

TREATMENT - Tail loss treatment

TAIL_LOSS - Did a lizard experience any type of tail loss (Yes or No)

STAGE - Before or after treatment

SVL - Body length

TRIAL - Trial number (2 repeats per stage)

ACTIVITY - Number of grid transitions made in a non-directed activity test

SOCIAL - Time spent basking with conspecifics

FORAGING - Time spent near a novel food item

BURST_SPEED - maximal sprint speed

AVERAGE_SPEED - average speed over trial runs (I.e. within each trial, a lizard was raced down a track 2 times)

TIME_IN_OPEN - proportion of time a lizard spent in the open (I.e. not in shelter, after a simulated predatory attack

TIME_IN_REFUGE - proportion of time a lizard spent in refuge after a predatory attack.

Funding

Australian Research Council Discovery Grant, Award: DP170100684