Inhaltszusammenfassung

Numerous introductions of common wall lizards (Podarcis muralis) into populations of native sand lizards (Lacerta agilis) are known from Germany. Since the sand lizard is strongly protected by national and European laws, it is crucial to evaluate the potential for a competitive displacement of sand lizards by alien wall lizards. We here studied for the first time the impact of introduced P. muralis on native sand lizards. We compared spatial distribution, micro-habitat choice, behavioural the...Numerous introductions of common wall lizards (Podarcis muralis) into populations of native sand lizards (Lacerta agilis) are known from Germany. Since the sand lizard is strongly protected by national and European laws, it is crucial to evaluate the potential for a competitive displacement of sand lizards by alien wall lizards. We here studied for the first time the impact of introduced P. muralis on native sand lizards. We compared spatial distribution, micro-habitat choice, behavioural thermoregulation, activity patterns and interactions of L. agilis in Nurtingen, Germany, in the presence and absence of introduced wall lizards originating from northern Italy. Our results show that the spatial distribution of both species and their local dispersal was strongly overlapping. The overlap in substrate selection between both species was significantly higher than expected (86%), with the strongest niche overlap between males of both species. Within the syntopic population, the population size of L. agilis was estimated at 69 +/- 7 individuals, whereas the population size of P. muralis was estimated at ca. 192 individuals. Dorsal temperature of P. muralis was on average 2 degrees C higher than the ambient air temperature (indicating a very effective thermoregulation), whereas dorsal temperature of L. agilis corresponded approximately with ambient air temperatures on both study sites. While P. muralis showed intraspecific interactions more often, interspecific interactions were rare (mainly basking at a distance). We did not detect any shift in habitat use or thermoregulation of sand lizards in the presence of introduced wall lizards. However, the strong niche overlap between both species in syntopy calls for further studies on their interspecific competition, both in situ (e.g., during the spring season) and experimentally. » weiterlesen» einklappen

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