Postautotomy tail activity in the Balearic lizard, Podarcis lilfordi

Abstract

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.

Evolution of antipredator behavior in an island lizard species,Podarcis erhardii(Reptilia: Lacertidae): The sum of all fears?

“…Researchers have long debated whether the highest incidences of autotomy should occur in areas with inefficient predators (because failed attacks are likely to result in autotomy and escape), or areas with the greater diversity of predators (Cooper et al ; Pafilis et al ; Bateman and Fleming ; reviewed in Bateman and Fleming ). In contrast to other studies on Mediterranean herpetofauna (Diego‐Rasilla ; Cooper et al ; Pafilis et al , ), we found that field autotomy rates did not reflect prevailing predation levels (in terms of predator diversity), nor were they correlated with standardized laboratory autotomy trials. Counterintuitively, the highest rates of autotomy were actually observed on islets completely isolated from predators, suggesting that autotomy on predator‐free islets was driven by intraspecific aggression and not by predation.…”

“…Lowered social status (Fox and Rostker ; Schall et al ; Salvador et al ) and decreased reproductive output are additional transient, negative effects incurred by recently autotomized individuals (Ballinger and Tinkle ; Vitt and Cooper ; Pafilis et al ; Cromie and Chapple ). Because autotomy can occur accidentally and without survival benefit during intraspecific interactions (Vitt et al , Jennings and Thompson ; Pafilis et al ; Vervust et al ), ease of autotomy in a population should reflect associated costs and benefits.…”

Sex, Age, and Population Density Affect Aggressive Behaviors in Island Lizards Promoting Cannibalism

“…However, lizards may also shed their tails as a consequence of intraspecific aggression (Langkilde & Shine ; Pafilis et al. ). Field observations are in accordance with our findings.…”

The blue lizard spandrel and the island syndrome

“…Of all the courtship encounters they observed 85.7% were initiated by blue males, vs. 7.1% initiated by brown males and 7.2% initiated by females. Individuals of a translocated population of St. Lucia whiptail Cnemidophorus vanzoi on Praslin Island [70] evolved increased growth rates, and high intensity of intraspecific competition (see also [37,71,72] on Balearic Podarcis lilfordi and on Skyros archipelago Podarcis gaigeae ). Praslin whiptails also have increased sexual size dimorphism and sexual dichromatism.…”