Comparative Postautotomy Tail Activity in Six Mediterranean Lacertid Lizard Species

Abstract

Tail autotomy, the self-induced tail separation from the body, is a common and effective antipredator mechanism in lizards. In this study, we examine the muscle energetics of tail shedding in six lacertid lizard species (Podarcis erhardii, Podarcis peloponnesiaca, Podarcis muralis, Podarcis gaigeae, Podarcis milensis, and Lacerta graeca) from the northeast Mediterranean region. Very long periods of postautotomy tail movement were demonstrated for all species ( min), and differences range p 6-8 among species were not statistically significant. Postautotomy tail movement, powered by anaerobic muscle activity, resulted in a strong increase in lactate concentrations and a concomitant depletion of muscle glycogen of exhausted tails relative to resting tails. No significant differences were found in either lactate or glycogen concentrations among the species examined. Duration of movement was negatively correlated with final lactate concentrations. The lack of differentiation in postautotomy energetic physiology in this group of species that have evolved under very different predation environments indicates that postautotomy muscle metabolism involves an overall conservative suite of characters.

Postautotomy tail activity in the Balearic lizard, Podarcis lilfordi

“…According to our predictions, as a consequence of the higher autotomy rate and the more intense movement, individuals from Colom and Sargantana should accumulate higher lactate levels than those from Aire. Nevertheless, we failed to detect any difference among populations just as recorded in other lacertids species (Pafilis et al 2005). Anaerobic metabolism is a common energy production mechanism among reptiles (Pough and Andrews 1985).…”

“…1) can be explained by the limited sample size in the case of predation simulation). Yet, the value for Aire (74%) is still high as compared to other lacertids (Pérez-Mellado et al 1997;Pafilis et al 2005). We believe that the reason must be attributed to the extremely dense population of the islet, estimated at around 4,100 individuals/ha (as opposed to 1,600 for Colom and 690 for Sargantana, Pérez-Mellado 1998).…”

“…Hence, it seems that the isolation time has been too short for a selective adaptation regarding postautotomic tail activity. This point is further indicated by the longer duration of tail thrashing of lacertids from eastern Mediterranean islands (Pafilis et al 2005) where predation pressure has been always heavy, as fossil records indicate (Kotsakis 1981;Caloi et al 1988). Postautotomy movement had to be more prolonged in eastern species so as to offset the severe predation strain.…”

“…Postautotomy movement is fueled by glycogen, which is oxidized anaerobically into lactate, providing the required energy to the muscles Fitzpatrick 1981, 1983;Gleeson 1996). Physiological pathways involved in tail muscle energetics have been reported as sharing a common pattern among species of the same family (Pafilis et al 2005). However, interspecies divergences in phylogeny may introduce biases that can easily obscure a real pattern or even create a spurious one (Huey 1987;Pianka 2001).…”

Effects of feral cats on the evolution of anti-predator behaviours in island reptiles: insights from an ancient introduction

“…Ease of caudal autotomy should also balance benefits and costs [14]. Because intact tails indicate social status and also play important roles in locomotion, courtship, defence and as lipid storage sites [15], the costs of caudal autotomy may outweigh the benefits under conditions of relaxed predation [16]. On small islands with few or no predators, the most expensive behaviours are predicted to be lost first [5].…”