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German Journal of Herpetology

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Žagar, A., A. Vrezec & M. A. Carretero

In Issues 2017

Do the thermal and hydric physiologies of Zootoca (vivipara) carniolica (Squamata: Lacertidae) reflect the conditions of its selected microhabitat? pp. 153-159.

Abstract. Preferred body temperature (Tp) is one of the most important ecophysiological traits in lizards, which, together with the rate of water loss (EWL), defines their thermal and hydric physiological fundamental niche. It is believed that an organisms' physiology and habitat use are connected by species being well adapted to the set of conditions experienced in space. Our aim was to first describe the Tp and EWL of Zootoca (vivipara) carniolica and its intraspecific (between sexes) variation, which also represents the first ecophysiological study of this (sub)species. During the reproductive season, the mean Tp was significantly higher in males than in females close to post-gravidity. There was no intraspecific difference in the diel variation of Tp; both sexes attained higher Tps in the first half of the day than in the second half of the day. EWL did not differ between sexes. Accumulative EWL rates showed a linear trend of increase with time and a gradual increase in the inter-individual variability. Secondly, to investigate if a species' ecophysiology parallels the thermal and hydric climatic conditions of its microhabitat, we placed data-loggers in their typical microhabitat in the northern Dinaric Mountains (S Slovenia). Microhabitat temperatures (T) were more variable throughout the day than relative humidity (RH), which remained stable at an average of 66%. The thermal quality of the environment between midday and 16 h was poor, since microhabitat T greatly exceeded lizards' Tp, thus representing thermally costly conditions. This period coincided with the observed selection of a lower Tp within the thermal gradient, which suggests an intrinsic thermoregulatory behavioural response with the aim of avoiding overheating. Z.(v.) carniolica attained a similar mean Tp compared to two sympatric but saxicolous lizards in the area, Iberolacerta horvathi and Podarcis muralis, but differed in its diel thermoregulatory pattern.  Unexpectedly, although Z. (v.) carniolica lives in a more humid microhabitat than the other two species (rocks), it lost more water under the same laboratory conditions.

Key words. Squamata, Lacertidae, Zootoca, ecophysiology, preferred body temperature, water loss rate, microhabitat, thermal quality index.