Joan Ll. Pretus

A rangewide phylogeography of Hermann's tortoise, Testudo hermanni (Reptilia: Testudines: Testudinidae): implications for taxonomy

Hermanns tortoise (Testudo hermanni), the best‐known western Palaearctic tortoise species, has a rare natural distribution pattern comprising the Mediterranean areas of the Iberian, Apennine, and Balkan Peninsulas, as well as Sicily, Corsica and Sardinia. The western part of this range is traditionally considered habitat for T. h. hermanni, while T. h. boettgeri occurs in the Balkans. Taxonomy of this tortoise has been challenged in recent years, with the two subspecies being considered full species and the central Dalmatian populations of T. h. boettgeri being considered a third species, T. hercegovinensis. Using an mtDNA fragment approximately 1150 bp long (cytochrome b gene and adjacent portion of tRNA‐Thr gene), we investigated mtDNA diversity with regard to contrasting concepts of two subspecies or three species. Seven closely related haplotypes were identified from the western Mediterranean and 15 different, in part much‐differentiated, haplotypes from the Balkans. Western Mediterranean haplotypes differ from Balkan haplotypes in 16–42 mutation steps. One to seven mutation steps occur within western Mediterranean populations. Balkan haplotypes, differing in 1−37 nucleotides, group in parsimony network analysis into three major assemblages that display, in part, a similar degree of differentiation to that of western Mediterranean haplotypes relative to Balkan haplotypes. Rates of sequence evolution are different in both regions, and low divergence, palaeogeography and the fossil record suggest a slower molecular clock in the western Mediterranean. While monophyly in western Mediterranean haplotypes is well‐supported, conflicting evidence is obtained for Balkan haplotypes; maximum parsimony supports monophyly of Balkan haplotypes, but other phylogenetic analyses (Bayesian, ML, ME) indicate Balkan haplotypes could be paraphyletic with respect to the western Mediterranean clade. These results imply a process of differentiation not yet complete despite allopatry in the western Mediterranean and the Balkans, and suggest all populations of T. hermanni are conspecific. In the western Mediterranean no clear geographical pattern in haplotype distribution is found. Distribution of Balkan haplotypes is more structured. One group of similar haplotypes occurs in the eastern Balkans (Bulgaria, Republic of Macedonia, Romania and the Greek regions Evvia, Macedonia, Peloponnese, Thessaly and Thrace). Two distinct haplotypes, differing in eight to nine mutation steps from the most common haplotype of the first group, are confined to the western slope of the Taygetos Mts. in the Peloponnese. Yet another group, connected over between four and 23 mutation steps with haplotypes of the eastern Balkan group, occurs along the western slope of the Dinarid and Pindos Mts. (Istria, Dalmatia, western Greece). Taygetos haplotypes are nested within other haplotypes in all phylogenetic analyses and support for monophyly of the other Balkan groups is at best weak. We conclude that using the traditional two subspecies model should be continued for T. hermanni. Phylogeographies of T. hermanni and Emys orbicularis, another codistributed chelonian, are markedly different, but share a few similarities. Both were forced to retreat to southern refuges during Pleistocene glaciations. With the advent of Holocene warming, E. orbicularis underwent rapid range expansion and temperate regions of Europe and adjacent Asia were recolonized from refuges in the Balkans and the northern Black Sea Region. By contrast, T. hermanni remained more or less confined to refuges and nearby regions, resulting in a much smaller range, and allopatric and parapatric distribution of haplotype groups and clades. MtDNA lineages are more diverse in E. orbicularis than they are in T. hermanni on southern European peninsulas, indicating several distinct glacial refuges in close proximity and extensive intergradation during Holocene range expansion for E. orbicularis. In T. hermanni it is likely that only on the Balkan Peninsula was more than one refuge located, corresponding to the parapatric ranges of haplotype groups currently there. On the old western Mediterranean islands Corsica and Sardinia no differentiated (E. orbicularis) or only weakly differentiated haplotypes (T. hermanni) occur, even though there is evidence for the presence of both species on Corsica since at least the Middle Pleistocene. High mountain chains constitute major barriers separating distinct mtDNA clades or groups in each species.

Scale dependency of insect assemblages in response to landscape pattern

Patches and their boundaries are sensitive to the scale at which they are viewed. The response of species to patchiness may depend on the resolution and on the extent by which the spatial pattern is perceived. The goal of this paper is to identify the scale at which forest spatial pattern causes changes in species richness and abundances of Dipteran and Homopteran species as a whole, and further on their distinctive ecological functional groups. Using remotely-sensed optical imagery, we described the landscape structure surrounding sampling sites. We used two approaches to deal with the problem of the scale of observation: 1) variation of extent using a multiscale analysis, and 2) comparison of two satellite sensors with different spatial resolutions (SPOT: 20 × 20 m, and Landsat TM: 30 × 30 m). The relationship between entomological data and landscape descriptors at different spatial scales was tested with the Mantel test, redundancy analysis and stepwise multiple linear regression. Relative abundances of Homopteran species were affected by landscape patterns at finer scales than in Diptera. The strength of response to landscape was different for each Dipteran functional group. The multiscale analysis also enabled the optimal scale (6.25 ha) of landscape pattern, accounting for 62% of the variation in Homopteran richness, to be identified. As a practical application, Homopteran richness was mapped by extrapolation of the regression function to the pixels of the image. Multiscale analysis provides an alternative view of fragmentation effects, which are traditionally studied through the patch-based approach, and highlights the importance of scale in ecological processes. The detection of optimal scales and the use of satellite images enable maps of important biotic indicators to be drawn up.

Characterizing human-modelled landscapes at a stationary state: a case study of Minorca, Spain

The island of Minorca, Spain, has become a patchy mosaic landscape as a result of centuries of human-induced fragmentation. The dynamics of the landscape elements and the spatial pattern of Minorca were analysed to test whether this human-modelled landscape was at a stationary state, and, if it was the case, to see whether the system could be characterized by a particular spatial pattern. Landsat TM satellite images were processed to derive land cover classification and vegetation index maps corresponding to the years 1984 and 1992, the best compromise between null cloudiness and maximum time span. The classification was used to test the stationary state by estimating the transition matrix of land cover. The Normalized Difference Vegetation Index (NDVI) was used to analyse the spatial pattern of change at the patch level. The spatial analysis of NDVI was based on four indices: fractal dimension, number and size distribution of patches, and spatial Kappa index. Those pattern descriptors were compared with values obtained from stochastic landscape simulations. Temporal analysis showed that land cover proportions remained approximately constant over the 8-year period, although interchange amongst patches existed. This suggested that the landscape of Minorca was close to a stationary state. The study of NDVI changes revealed that the spatial structure was different from that of neutral models and presented scale invariance properties. Results from land cover transitions and from NDVI patterning suggest that the landscape of Minorca is a critical system, in the framework of the self-organized criticality hypothesis, i.e. the mosaic of patches would self-organize at the frontier of a dynamic equilibrium constituted by the balance between disturbances and successional processes.

Assessing the applicability of stable isotope analysis to determine the contribution of landfills to vultures’ diet

Human activities cause changes to occur in the environment that affect resource availability for wildlife. The increase in the human population of cities has led to a rise in the amount of waste deposited in landfills, installations that have become a new food resource for both pest and threatened species such as vultures. In this study we used stable isotope analysis (SIA) and conventional identification of food remains from Egyptian Vultures (Neophron percnopterus) to assess the applicability of SIA as a new tool for determining the composition of the diets of vultures, a group of avian scavengers that is threatened worldwide. We focused on an expanding Egyptian Vulture population in NE Iberian Peninsula to determine the part played by landfills and livestock in the diet of these species, and aimed to reduce the biases associated with conventional ways of identifying food remains. We compared proportions of diet composition obtained with isotope mixing models and conventional analysis for five main prey. The greatest agreement between the two methods was in the categories ‘landfills’ and ‘birds’ and the greatest differences between the results from the two methods were in the categories ‘livestock’, ‘carnivores’ and ‘wild herbivores’. Despite uncertainty associated to SIA, our results showed that stable isotope analysis can help to distinguish between animals that rely on waste and so present enriched levels of δ 13C than those that feed on the countryside. Indeed, a high proportion of food derived from landfills (nearly 50%) was detected in some breeding pairs. Furthermore we performed GLMM analyses that showed that high values of δ 13C in Egyptian Vulture feathers (a proxy of feeding in landfills) are related with high levels of humanization of territories. This method has the potential to be applied to other threatened vulture species for which there is a lack of information regarding resources they are consuming, being especially important as the main causes of vultures decline worldwide are related to the consumption and availability of food resources.