The Herpetological Journal

https://doi.org/10.33256/hj31.2.7076

pp. 70-76

Authors: Yole Caruso, Daniele Macale, Luca Luiselli & Leonardo Vignoli

Abstract: Lizard thermoregulation is costly and is largely behavioural. Podarcis raffonei, endemic of few islets of the Aeolian archipelago (southern Italy), is one of the most threatened lizards in Europe, its survival being under threat also due to the presence of the congeneric P. siculus, a successful invader characterised by behavioural plasticity and effectiveness and precision at regulating body temperature (Tb). We tested whether thermoregulation behaviour diverges between the two species by analysing (i) the heating rates under a standard thermal condition, and (ii) the temperature at which lizards ended basking (T_final) along a thermal gradient. Overall, we found behavioural differences between the two lizards (i.e. P. siculus exhibited lower T_final), although both species had comparable heating rates and thermoregulated in the same thermal conditions. The invasive P. siculus had lower T_final and, since heating rates were similar between species, it expended less time basking than native P.
raffonei. We speculate that the observed thermal ecology differences could provide a selective advantage to P. siculus in the harsh island environment.

Keywords: Podarcis raffonei, Podarcis siculus, lizard, biological invasion, competition