Publications by Year: 2013

CHOVALOPOULOU E.M., E.VALAKOS SKMANOLIS. Sex determination by three-dimensional geometric morphometrics of the palate and cranial base. Anthrop.Anz. J.Biol. Clinic. Anthrop. Anthrop.Anz. J.Biol. Clinic. Anthrop. 2013;70:407-425.
Sagonas K, Valakos ED, Pafilis P. The impact of insularity on the thermoregulation of a Mediterranean lizard. Journal of Thermal Biology. 2013;38:480-486.Abstract
Abstract The overall biology of ectotherms is strongly affected by the thermal quality of the environment. The particular conditions prevailing on islands have a strong effect on numerous features of animal life. In this study we compared mainland and island populations of the lizard Lacerta trilineata and hypothesized that insularity would affect the thermoregulatory strategy. Continental habitats were of lower thermal quality, experiencing more intense fluctuations and had higher values of operative temperatures. Nevertheless mainland lizards selected for higher body temperatures in the lab and showed more effective thermoregulation during summer than their island peers. Lizards achieved similar body temperatures in the field in both types of habitat, underlining the importance of predation as a potential factor to mainland lizards that failed to reach their higher thermal preferences. Both island and mainland populations of L. trilineata have been adapted to their thermal environment, supporting the labile view on the evolution of thermal physiology for this species.
Sagonas K, Meiri S, Valakos ED, Pafilis P. The effect of body size on the thermoregulation of lizards on hot, dry Mediterranean islands. Journal of Thermal Biology. 2013;38:92-97.Abstract
Body size shapes the overall biology of organisms. We assessed the impact of size on temperature regulation in populations of normal-sized and large-bodied insular Mediterranean lizards (Podarcis gaigeae, Lacertidae). We hypothesized that large lizards would achieve higher body temperatures and thermoregulate more effectively than their smaller kin. Large- and small-bodied lizards share the same thermoregulation pattern, achieving similar body temperatures in the field. Large lizards, however, prefer higher set-point temperatures. Lizards in both populations thermoregulate effectively, but large lizards thermoregulated less effectively than normal sized lizards. The particular conditions at the islet that harbors the large-bodied population (harsh intraspecific competition) seem to account for this pattern.
Pafilis P, Anastasiou I, Sagonas K, Valakos ED. Grazing by goats on islands affects the populations of an endemic Mediterranean lizard. Journal of Zoology. 2013;290:255-264.Abstract
Grazing of goats on Mediterranean islets is a common practice. Its consequences on plant communities are well documented, although not on vertebrates. We aim to shed light on the effect of livestock farming on lizards by investigating five populations of the insular lizard, Podarcis gaigeae, differing in the duration and intensity of grazing. Data on grazing regime, invertebrate abundance, tick prevalence, infestation levels, gull nests and lizard densities were collected during a period of 6 consecutive years. Grazing had a negative impact on insect populations, thus decreasing food availability for lizards. Tick prevalence and infestation levels were higher in places of continuous grazing. Goat activity disturbed gulls, which avoid nesting, so depriving the islets of marine subsidies. As a consequence of all these factors, lizard densities were higher in ungrazed and lower in grazed biotopes. Grazing effects were more severe on islets communities than on the main island populations. Our data imply that management action should be taken to conserve the highly diverse islet populations.
Kotsakiozi P, Rigal F, Valakos ED, Parmakelis A. Disentangling the effects of intraspecies variability, phylogeny, space, and climate on the evolution of shell morphology in endemic Greek land snails of the genus Codringtonia. Biological Journal of the Linnean Society. 2013;110:796-813.Abstract
Extensive variation in land snail shell morphology has been widely documented, although few studies have attempted to investigate the ecological and evolutionary drivers of this variation. Within a comparative phylogenetic framework, we investigated the temporal and spatial evolution of the shell morphology of the Greek endemic land snail genus Codringtonia. The contribution of both inter- and intraspecies shell differentiation in the overall shell variability is assessed. The effect of climate, space, and evolutionary history on the shell variability was inferred using a variance partitioning framework. For Codringtonia species, intraspecies divergence of shell traits contributes substantially to the overall shell variability. By decomposing this variability, it was shown that the overall shell size of Codringtonia clades is phylogenetically constrained, related to early speciation events, and strongly affected by large-scale spatial variability (latitudinal gradient). The effect of climate on shell size cannot be disentangled from phylogeny and space. Shell and, to a larger extent, aperture shape are not phylogenetically constrained, and appear to be mostly related to conspecific populations divergence events. Shell shape is substantially explained by both climate and space that greatly overlap. Aperture shape is mainly interpreted by medium to small-scale spatial variables. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, ●●, ●●–●●.