Postautotomy tail activity in the Balearic lizard, Podarcis lilfordi.
Caudal autotomy is an effective antipredator strategy widespread among lizards. The shed tail thrashes vigorously for long periods to distract the predator and facilitate the lizard's escape. This movement is maintained by energy supplied by the anaerobic conversion of glycogen into lactate. It has been suggested that lactate accumulation serves as an index for the vigor of tail thrashing. We made three predictions: (1) tail loss frequency should be higher under heavier predation regime, (2) the duration of postautotomy tail movement should be extended in populations under heavy predation pressure as an adaptation to the higher risk and the increased need for defense, and (3) as result, lactate in these tail tissues should be concentrated at higher levels. To eliminate the impact of phylogeny and environmental factors on the interpretation of our result, we focused exclusively on one species, the Balearic lizard (Podarcis lilfordi). We studied three populations under different predation pressure but sharing the same climatic conditions. We found no differences among the studied populations either in postautotomy duration of tail movement or in levels of final lactate accumulation while autotomy frequency was higher where predation pressure was more intense. Tail loss effectiveness is directly influenced by the level of predation, while secondary features of the trait appear to remain independent from the impact of environment.
Pafilis
Panayiotis
P
Department of the Environment, University of the Aegean, Lofos Xenia, 81100 Mytilene, Lesvos, Greece. pafilis@aegean.gr
Pérez-Mellado
Valentín
V
Valakos
Efstratios
E
D000818:Animals; D001717:Birds; D006003:Glycogen / Q000378:metabolism; D006115:Greece; D006801:Humans; D008116:Lizards / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D011156:Population Density; D011235:Predatory Behavior; D051381:Rats; D012911:Snakes; D013623:Tail / Q000502:physiology*
D006003:Glycogen