Relative Apportioning of Resources to the Body and Regenerating Tail in Juvenile Leopard Geckos (Eublepharis macularius) Maintained on Different Dietary Rations

Abstract

Caudal autotomy is a widespread phenomenon among lizards, and similar processes occur in other groups of vertebrates and invertebrates. Many costs have been associated with autotomy, including the regeneration of lost biomass. For lizards, it is not known whether resources are preferentially directed toward caudal regeneration or whether regeneration occurs only when resources are abundant. Conflicting information is present in the literature, and an absence of controlled experiments prevents determination of what pattern of regeneration may occur under a given set of circumstances. We employed the leopard gecko, a fat-tailed species, to examine whether tail regeneration is a priority and, if so, whether it remains so when resources become limiting. We explored this through caudal autotomy and dietary manipulation under conditions that ensured that differences in diet were sufficient to permit differential growth. We examined juvenile leopard geckos because these animals are rapidly growing and allocation of energy is not compromised by reproductive investment. The effects of dietary resource availability and the demands of caudal regeneration were compared in intact and regenerating animals. Our evidence indicates that caudal regeneration is a priority, even when resources are limiting. We conclude that tail regrowth is a priority that is associated with long-term survival and possibly reproductive success.

Tail autotomy and subsequent regeneration alter the mechanics of locomotion in lizards

“…The Journal of Experimental Biology (2014) regeneration are unknown, growth and maturity have been suggested to influence regeneration rates in geckos (Congdon et al, 1974;Vitt et al, 1977;Lynn et al, 2013). Here, we show that in mature adult female leopard geckos, fully regenerated tails are smaller in both weight and volume than the original tails and take on a new shape, which is shorter and wider than the original (Fig.…”

“…Although survival is likely enhanced, we present several biomechanical ramifications of the associated alteration of both body weight and relative location of the CoM. For this we used E. macularius, which has the ability to autotomize and relatively rapidly regenerate a bulky tail (Lynn et al, 2013). Previous work relating to the effects of autotomy has focused on differences in gross morphology, anatomy, histology and development between original and regenerated tails.…”

“…Previous work relating to the effects of autotomy has focused on differences in gross morphology, anatomy, histology and development between original and regenerated tails. Although it is frequently noted that the structure of the regenerated tail differs from that of the original (Goss, 1969;McLean and Vickaryous, 2011;Delorme et al, 2012), disparities in size and shape are only briefly mentioned (Whimster, 1978;Lynn et al, 2013) and have not previously been quantified. Additionally, such studies have generally been conducted on juvenile animals and although ontogenetic differences in tail…”

“…1). Interestingly, the regenerated tails of juveniles of the same species are not smaller in weight (Lynn et al, 2013), suggesting that tail regeneration is not afforded such a high priority in adults and that the costs of regenerating a larger tail may outweigh the benefits. We hypothesize that the tail does not return to its original shape because regenerating a replica of the original might not be essential for locomotion in E. macularius.…”

“…Because losing a relatively large tail is likely to elicit a greater change in locomotion (McElroy and Bergmann, 2013), this species is well-suited for examining the effects of autotomy on locomotor mechanics. Additionally, leopard geckos are an established study system for autotomy and the relative ease of inducing autotomy in this species has been noted (Higham and Russell, 2010;McLean and Vickaryous, 2011;Delorme et al, 2012;Higham and Russell, 2012;Lynn et al, 2013).…”