Differential effects of habitat loss on occupancy patterns of the eastern green lizard Lacerta viridis at the core and periphery of its distribution range

Abstract

The effects of habitat loss on the distribution of populations are often linked with species specialization degree. Specialist species can be more affected by changes in landscape structure and local patch characteristics compared to generalist species. Moreover, the spatial scale at which different land covers (eg. habitat, cropland, urban areas) affect specialist species can be smaller. Specialization is usually assumed as a constant trait along the distribution range of species. However, for several taxa, there is evidence of higher specialization degree in peripheral populations compared with populations in the core. Hence, peripheral populations should have a higher sensitivity to habitat loss, and strongest effects should be found at a smaller spatial scale. To test these expectations, we implemented a patch-landscape approach at different spatial scales, and compared effects of landscape structure and patch characteristics on occupancy probability among northern peripheral, more specialized populations (Czech Republic) and core populations (Bulgaria) of the eastern green lizard Lacerta viridis. We found that landscape structure and patch characteristics affect differently the occupancy probability of Lacerta viridis in each region. Strongest effects of habitat loss were found at a spatial scale of 150m around patches in the periphery, but at a scale of 500m in the core. In the periphery occupancy probability of populations was principally affected by landscape composition, and the effect of habitat quality was stronger compared to core populations. In the core, persistence of populations was mainly explained by characteristics of the spatial configuration of habitat patches. We discuss possible ecological mechanisms behind the relationship between sensitivity to habitat loss, populations' specialization degree and position in the distribution range, and suggest conservation measures for L. viridis.

Habitat preferences of European green lizard Lacerta viridis (Laurenti 1768) in a protected area, Romania

“…Thermoregulation implies moving between sun and shade (Huey, 1974), and our results show that the two most important habitat variables are the presence of shrubs and trees in combination with grassland on a small scale, thus providing a mosaic of different ecological conditions. Our results confirm other findings that heterogeneous areas with bushy parts are most suitable for the species (Heltai et al, 2015;Prieto-Ramirez et al, 2018, 2020a. The results regarding microhabitat use show that shrubs and logs the most used features by lizards for basking and as shelter and/or hiding place, confirming other observations for the European Green lizard (Heltai et al, 2015), but also for related species L. bilineata (Luppi et al, 2020).…”

Ontogenetic Habitat Use and Density of the Green Lizard (Lacerta bilineata) in Contrasted Landscapes in France and Italy

“…The Italian dataset revealed that adults versus juveniles selected preferentially different bush species-dominated habitats for their activities. Although it is generally considered that for lizards (and reptiles in general), the actual plant species present are less important than the physical influence they create [55], in the case of green lizards, we demonstrated that plant species are very relevant, as they emerged as significant factors in the habitat use for males and females (Rubus sp.) as well as for juveniles (Spartium sp.).…”

“…The comparative evidence from these studies shows that very local (habitat and climatic) conditions may strongly condition the ecological requirements of green lizards, and consequently that site-specific studies should always be carry out for a reliable management of the various L. bilineata populations. In this regard, in the closely-related Lacerta viridis, there was evidence of higher specialization degree in peripheral populations compared with populations in the core, with peripheral populations exhibiting a higher sensitivity to habitat loss, especially at small spatial scale [55]. Further studies should explore whether the same pattern occurs in L. bilineata populations.…”

Effects of landscape structure and patch characteristics on the density of central populations of the eastern green lizard Lacerta viridis

“…I applied a patchlandscape approach integrating landscape parameters across spatial scales with patch and within-patch parameters. Effects of habitat loss on occupancy patterns of L. viridis have recently been investigated in the same study system (Prieto-Ramírez et al, 2020), with occupancy being found to be mostly defined by landscape configuration, with the strongest effect of the overall habitat loss process occurring at the 750 m scale around patches. No negative effect of isolation was found, and at the patch level, occupancy depended on patches with both long perimeter and enough core area in the interior, indicating that the species uses not only the border but also the interior of patches.…”

“…is a robust combination of survey design types, solving mismatches between occupancy and abundance data gathering methods.Concerning the necessary conservation measures for L. viridis in the studied region,Prieto-Ramírez et al (2020) highlighted the importance of protecting and restoring riparian vegetation, which might be an important corridor connecting populations, to increase the occupancy probability of remnant patches. In addition to this recommendation, early conservation measures to avoid the decline of still extant populations of L. viridis should include ensuring enough patch interior area, restoring habitat at small scales (~50 m), at which cropland and urban areas are exerting strong negative pressure, and protecting and restoring habitat at large scales (~1.5 km), which cover the species' maximum dispersal distance and at which connectivity can be much more strengthened.Understanding the response of wild animal populations to habitat loss at different stages of the population extinction process, and at different spatial levels, is of vital importance to identify the best possible conservation measures.…”