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Dietary studies are essential to unravel the functioning of ecosystems and ultimately to understand biodiversity. This task, which at first may seem simple, becomes especially complex in those cases of omnivorous species with highly variable diets. In this regard, the emergence of next-generation DNA sequencing methodologies represents a powerful tool to address the problem. Here we implement a high-throughput metabarcoding strategy based on the analysis of four molecular markers aimed at sequencing both mitochondrial (animal prey) and chloroplast (diet plants) genome fragments from fecal samples of two lizard species endemic to the Balearic Archipelago (Podarcis lilfordi and P. pityusensis) obtained through non-invasive methods. The results allowed for the characterization of their diets with a high degree of taxonomic detail and have contributed a large number of new trophic records. The reported diets are based mainly on the consumption of arthropods, mollusks and plants from a diversity of taxonomic orders, as well as carrion and marine subsidies. Our analyses also reveal inter- and intra-specific differences both in terms of seasonality and geographical distribution of the sampled lizard populations. These molecular findings provide new insights into the trophic interactions of these threatened endemic lizards in their unique and isolated ecosystems.

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Gut microbial communities provide essential functions to their hosts and are known to influence both their ecology and evolution. However, our knowledge of these complex associations is still very limited in reptiles. Here we report the 16S rRNA gene faecal microbiota profiles of two lizard species endemic to the Balearic archipelago (Podarcis lilfordi and P. pityusensis), encompassing their allopatric range of distribution through a noninvasive sampling, as an alternative to previ- ous studies that implied killing specimens of these IUCN endangered and near-threatened species, respectively. Both lizard species showed a faecal microbiome composition consistent with their omnivorous trophic ecology, with a high representa- tion of cellulolytic bacteria taxa. We also identified species-specific core microbiota signatures and retrieved lizard species, islet ascription, and seasonality as the main factors in explaining bacterial community composition. The different Balearic Podarcis populations are characterised by harbouring a high proportion of unique bacterial taxa, thus reinforcing their view as unique and divergent evolutionary entities.

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In this article an introduction is given on the geological history leading to the separation of Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883) as separate species, as well as a Holocene sea level rise model which combined with bathymetric data leads to an estimation of recent divergence time in populations of the Balearic lizards.

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New data on estimated divergence times of the populations of lacertid lizards in the Balearic Islands are provided in this second update of the October 2011 article: Estimating recent divergence time in populations of Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883) (VAN DEN BERG 2011), which received its first update May 2012. In most cases better estimations of divergence times were available by using the NAVIONICS SonarCharts™webapp.

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More than three decades of fascination for the endemic Balearic sisterspecies Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883), resulted in 30 trips (1980-2013) to the home of these lacertid lizards, in which we studied their ethology as well as their distribution and geographical differences in pattern and coloration. In comparison to prior scientific studies that led to an inflationary description of subspecies, we often found wide variations within populations and their subspecific characteristics. The question “To be distinct, or not to be distinct” is, to our opinion, not answered correctly in most cases. In order to gather data for a future revision of the present subspecific order, we started in 2011 to collect data of these lizards in a structured way, and storing this data in a free accessible database (www.pityusensis.nl). Later in 2011 we enhanced our dataset by gathering tissue samples of the lizards, using the non invasive technique of buccal swabbing, for future accompanied DNA research.

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This is already our sixth report in a series on our whereabouts while collecting data for a future revision of the present subspecific order of the endemic Balearic sisterspecies Podarcis lilfordi (GÜNTHER, 1874) and Podarcis pityusensis (BOSCÁ, 1883), which data are stored in our database at www.pityusensis.nl (VAN DEN BERG & ZAWADZKI 2011 ; VAN DEN BERG et al. 2013 ; VAN DEN BERG et al. 2014a ; VAN DEN BERG et al. 2014b ; VAN DEN BERG et al. 2015). During this trip from the 27th of March until the 9th of April 2016, we were able to collect data at some mainland Ibiza locations, as well as on the following adjacent islands: Sa Mesquida, S’Hort, S’Illeta de Cala Salada, Vedranell, Rates, Bleda Plana, Murada, Bleda Na Bosc and S’Espardell de S’Espartar. We continue with the ventral coloration as a possible determining key as introduced in our 2014 trip report (VAN DEN BERG et al. 2014b). Images of the anal shields are presented of each lizard for purposes of illustration.

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Es wird über einen 1930 angesetzten Versuch berichtet, bei dem auf einem bis dahin eidechsenfreien Felseiland (Dado Grande bei Ibiza, Pityusen) Männchen einer melanistischen und Weibchen einer grünen Inselpopulation von Podarcis pityusensis ausgesetzt wurden. Die Untersuchung von sechs fünf Jahre später gefangenen Tieren ergibt, dass die Vermischung zu erhöhter Variabilität und gesteigertem Größenwuchs geführt hat. Eine erneute Kontrolle dieses noch vorläufigen Ergebnisses wird angeregt.

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The association between polymorphism at the mc1r locus and colour variation was studied in two wall lizard species (Podarcis lilfordi and P. pityusensis) from the Balearic archipelago. Podarcis lilfordi comprises several deep mitochondrial lineages, the oldest of which originated in the Pliocene, while much shallower mitochondrial lineages are found in P. pityusensis. Here, we examined whether specific substitutions were associated with the melanic colouration found in islet populations of these species. Homologous nuclear sequences covering most of the mc1r gene were obtained from 73 individuals from melanic and non-melanic Podarcis from different populations (the entire gene was also sequenced in six selected individuals). MtDNA gene trees were also constructed and used as a framework to assess mc1r diversity. Mc1r showed greater polymorphism in P. lilfordi than in P. pityusensis. However, we observed no substitutions that were common to all melanic individuals across the two species. Only one significant association was detected in the mc1r partial sequence, but this was a synonymous A/G mutation with A alleles being more abundant in melanic populations. In addition, there were no associations between the main dominant phenotypes (green and brown, blue and yellow spots and ventral colour) and synonymous or non-synonymous substitutions in the mc1r gene. There was no statistical evidence of selection on mc1r. This study suggests no relationship between mc1r polymorphism and colour variation in Balearic Podarcis.

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EL ESTUDIO ABORDADO EN LA TESIS VERSA SOBRE LA CARACTERIZACION TAXONOMICA DE LA LAGARTIJA DE LAS PITIUSAS PODARCIS PITVUSENSIS. SE ANALIZAN LAS DISTINTAS POBLACIONES DESDE TRES ASPECTOS DISTINTOS: EL ANALISISBIOMETRICO EL ANALISIS ELECTROFORETICO DE DISTINTAS PROTEINAS Y EL ANALISIS COLORIMETRICO. LOS ANALISIS ESTADISTICOS APLICADOS SOBRE LAS VARIANTES BIOMETRICAS DEMUESTRAN LA EXISTENCIA DE DIVERSOS GRUPOS DE POBLACIONES MUY SEMEJANTES ENTRE SI. LA VARIABILIDAD DE LA ESPECIE NO SOLO ES FENOTIPICA SINO QUE TAMBIEN ES GENETICA DETECTANDOSE UNA DIVERSIDAD EN ESTOS CARACTERES SUPERIOR A LA ESPERADA EN REPTILES. SE OBSERVA UNA ALTA HETEROSIS QUE ES CARACTERISTICA DE LA ESPECIE LO QUE PARECE DEMOSTRAR QUE ESTA SE ENCUENTRA EN LAS PRIMERAS FASES DE COLONIZACIONY ADAPTACION A LOS DIFERENTES HABITATS OFRECEN LAS ISLAS QUE OCUPA. SE CONSTATA LA ACCION DEL EFECTO FUNDADOR Y LA DERIVA GENETICA EN LOS TRES ASPECTOS CONSIDERADOS EN LA TESIS ASI COMO UNA TENDENCIA EVOLUTIVA HACIA EL AUMENTO DE TAMAÑO SIEMPRE QUE NO EXISTA UNA PRESION SELECTIVA CONTRARIA. SUCEDE LO MISMO CON EL MELANISMO. CONSIDERANDO EL ESTADO EVOLUTIVO ACTUAL DE LA ESPECIE REFLEJADO EN LA PLASTICIDAD DE LAS DISTINTAS POBLACIONES DE ESTALAARTIJA Y EN LA ADAPTACION QUE MANIFIESTAN EN CADA NICHO CONCRETO ASI COMO EL CONCEPTO RESTRICTIVO ACTUAL DE SUBESPECIE LA AUTORA CONSIDERA QUE SOLO PUEDEN CONSIDERARSE SEIS TAXONES SUBESPECIFICOS O SUBESPECIES DE LA LAGARTIJA DE LAS PITIUSAS.

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In this paper are presented the results obtained with 45 populations of Podarcis pityusensis. Several multivariant technics are performed: discriminant analysis, cluster analysis and canonic analysis of populations. These populations present gradual change in all their biometric characteristics, and also a great interpopulation variability, that invalidate th statistical methods to discriminate between all of them. In different analysis very related population groups are found, that suggests they are constitute the same subspecies, in the actual taxonomic sense. These groups always inhabits islands with the same geological age, it is therefore necessary to complete the study with othr biological reflections, all of which are getting ready.

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The dorsal, side and belly colours of 118 specimens of Podarcis pityusensis have been analysed with physical methods. Twenty samples from 16 islands have been chosen, 3 of then from Eivissa Island (Ibiza), 2 from Formentera Island and 2 from Espardell Island. The results reveal great colouration differences between the same island samples and sometimes similar colouration between different islands (different subspecies). specimens. This feature seems to show the colour criteria is not useful in taxonomic subjects for this species.

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The variation in morphological and colouring features shown by the insular lacertid populations of Podarcis pityusensis is discussed from the point of view of their adaptive advantages to specific insular ecosystems. Insularity factors, i.e. area and island-age, have been found to be related to average body size, and the average luminosity of each population. Populations tend to show a size increase, a greater morphological homogeneity and darker dorsal colouring on smaller and older islands. Genetic drift seems to play a secondary role, whereas a positive selection in favour of melanism and giantism is observed. Both features are not linked as cause and effect, but seem to share a common cause: isolation and time enough to allow selection to take place. Predation, though slight in degree, does exist, and seems to be one of the selective pressure favouring melanism, together with the parallel trend towards an increase in body size and the need to an effective thermoregulation during the early hours of the day.

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The Ibiza wall lizard is the symbol of the Pityusic-Archipelago, but what makes this colorful reptile so special? The Symbol: wall lizards of Ibiza and Formentera will take you on a journey into the culture, biology, ecology, and conservation of Ibiza and Formentera’s most iconic animal.

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Comparative analyses were carried out about the variability of the pileal shields of different species belonging to the family Lacertidae. The results of the comparisons have been evaluated in respect to the phylogenetical relationships existing between the different genera and species of the family.

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Color patterns of adult and juvenile Podarcis pityusensis maluquerorum are described. Keeping and breeding of this lizard species is reported.

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546 lizards of different geographically isolated populations of the specus Lacerta pityusensis were studied using an systematic criteria correlative and allometric changes of body proportions, coloration and pattern. Some other criteria often used in systematic studies on southern European lizards were unsuitable, since they do not differ significantly between the populations. With the exception of the Trocados (Trocardors) lizard (L. p. grueni) all adults of the populations on the seperate offshore islands increase their body size, in particular L. p. grossae on St. Eulalia (Illa de Santa Eulalia) and L. p. maluquerorum on Bleda Nebosque Island (Na Bosc). The studies on correlative and allometric changes of body proportions showed: All criteria show a marked sexual dimorphism, the males are larger and have longer pilei and hindlimbs. The allometric changes in length of pileus / width of pileus were found to be possitive in males however negativ in females in all populations except the N-Formentera lizards. The females of the geographically isolated populations differ more between each other and in comparison with Ibiza females than do males. Lizards of the island populations have more slender pilei than Ibiza lizards. The females have longer hindlimbs but in some populations the hindlimbs of the males show a more negative allometric growth. Smaller adult males of these populations have longer while larger males have shorter hindlimbs than the Ibiza lizards. The studies of coloration and pattern showed that in particular the populations of the east coast of Ibiza differ from those given in other studies. In the population of L. p. grossae on St. Eulalia (Illa de Santa Eulalia) grey green individuals without a red belly are found, in the population of L. p. canensis on Es Cana Island (Caná) are some light green lizards. The females of L. p. redonae (Redonda de Santa Eulalia) and L. p. canensis (Caná) were described the first time. The population on east coast islands show no tendency to darker coloration. The populations longest isolated display the most brightest colours. L. p. grueni inhabits the peninsula (not island) Trocados (Trocadors). This subspecies is distributed over the extreme north of Formentera and in the south of it`s range hybridisation with the subspecies L. p. formenterae occurs. The lizards of playa La Sabina, N-Formentera and some related offshore islands are with regard to all criteria intermediate to the lizards of Ibiza and the remaining Formentera. The subspecies L. p. algae (Pouet), subformenterae (Conejo de Formentera) and sabinae (Sabina), described from that region, are considered as synoyms of L. p. pityusensis as well as L. p. formenterae. Since the lizards of the Islas de Purroige (Ses Illetes de Purroig) differ hardly from the lizards of Ibiza, this subspecies (L. p. purroigensis) is considered a synonym of L. p. pityusensis. Lacerta p. zenonis from the tiny island Escui de Esparto (Escull de S`Espartar) probably does not differ from L. p. kameriana from the island of Esparto (Espartar). In future, the ecology, structure and size of the isolated lizard populations shall be studied and compared. It is suggested that the single island represent different eco-systems. An analysis shall be done on those parameters which maintain natural selection and are thus most imortant for the evolution of the lizards. It is considered that the social behaviour is of relevance to population dispersion and density and the regulation of population size.

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The status of the populations of Podarcis pityusensis on about 70 islets and small islands around Ibiza and Formentera (Balearic Islands) is examined, using data from our own observations, and, to a lesser amount, other publications. Lizard populations were found on 43 islets, but data are lacking for another 13. Only 10 sites (18 %) have abundant and well-maintained populations. In 13 localities (23%), there is no geographic isolation between the populations, or this isolation is very poor and incomplete. The high probability of populations mixing, or actual observation of this mixing, in 19 islands (34%) is indicated. Human pressure on lizard populations is strong in 14 cases (25 %). And finally, 18 populations (about one third) may be considered highly endangered or already extinct by elimination or genetic mixing with other populations. Among the subspecies which became extinct through mixing are P.p. miguelensis, P.p. subformenterae, P.p. algae, P.p. sabinae and P.p. grueni. The need for adequate protective measures aimed at the conservation of the remaining populations is emphasized.

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A very small population (five lizards in 1998), product of the hybridization of P. p. maluquerorum and P. p. pityusensis, released by M. Eisentraut in 1930 survives in Dau Gran islet (Ibiza, Balearic Islands). The study of hybrids collected in 1935 and three present day specimens (two males and one female) allow to verify a tendency towards an increase in body size and a darker coloration of lizards. We consider that cannibalism is one of the principal selective factors in these extreme conditions that implie relatively quick evolutionary changes. This population can be representative of other populations also living in small islets with limited resources.

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Available data regarding conservation status of lizard populations from Balearic Islands, as well as threat factors affecting them are presented. Some populations are highly threatened, due to their intrinsic limitation of island surface occupied and, in addition, there are cases of viable artificial populations. Hence, we propose the translocation of most threatened populations to islets today unoccupied by lizards. We show the critria under which such operation could be performed.

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While the use of faecal pellets is widely accepted as a primary methodological source of data for dietary studies, a recent paper advocated for the use of gut contents. This was due to the fact that faecal samples would give biased results of the diet of arthropod predators, due to a lower representation of soft-bodied prey in faecal pellets. To test this assumption, we compared the spring diet of several populations of two insular lizards from the Balearic Islands (Spain), Podarcis lilfordi and Podarcis pityusensis, using both faecal pellets and gut contents. Our results do not support the supposed bias of dietary analyses based on faecal pellets. Indeed, soft-bodied prey and particularly insect larvae are often equally represented in faecal pellets and gut contents. Alternatively, soft bodied prey are represented in different proportions in gut contents and faecal pellets, but in some cases with higher proportions being observed in the gut contents, and in other cases with higher proportions in faecal samples. We conclude that faecal pellets can be a reliable source of information for dietary studies.

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The Ibizan wall lizard, Podarcis pityusensis, was the subject of several documented translocations by the German vertebrate zoologist Martin Eisentraut, in 1930. He aimed to initiate long-term experiments into the evolution of melanism and other morphological traits and accordingly he designed introductions into five islets that (he believed) contained no lizards. In this study, we analyzed the genetic and morphological characteristics of individuals we found there. We found no lizards on two of the islets, namely Escull de Tramuntana and Galera, but for the first time, detected a large population on a third islet, Es Vaixell. Eisentraut founded the Es Vaixell population with nonmelanistic Ibizan specimens, but the present day population of Es Vaixell was found to be fully melanistic. Genetic markers support a strong similarity between Es Vaixell and its neighbour islet, Na Gorra, and indicate that, in all likelihood, the individuals introduced by Eisentraut have left no descendants. It is likely that Es Vaixell already contained lizards prior to this introduction. Analyses of microsatellite DNA placed individuals from a fourth islet, Dau Gran, with those of one of its source islet, Escull Vermell. They are also morphologically close to individuals from Escull Vermell. This suggests that selection pressures could have favoured the Escull Vermell phenotype following introduction. For reasons we discuss, the translocations have revealed less than Eisentraut would have originally hoped for. Although evolutionary processes are normally time-consuming, these translocations do provide some potential insights into the rapid evolution of lizard morphology following colonization.

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Comparisons among eight populations of Podarcis lilfordi, seven of Podarcis pityusensis (representative lizards of the Balearic Archipielago), and one of Podarcis hispanica atrata fro the Columbretes Islands, have been made from a morphological point of view, measuring 15 morphometric characters of the lizards. Cluster and discriminant analyses were obtained for males and females to show the relationships among the different populations and species. These analyses gave three groups: one of them with the most P. lilfordi populations, other with the most P. pityusensis populations, and a well seperated group with the P. hispanica atrata species. Some populations connect the groups of P. lilfordi and P. pityusensis. The possibility that P. lilfordi and P. pityusensis be two pattern of variation inside the same species instead of two well differentiated species is considered, altrough further studies are necessary.

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Two monophyletic sister species of wall lizards inhabit the two main groups of Balearic Islands: Podarcis lilfordi from islets and small islands around Mallorca and Menorca and Podarcis pityusensis from Ibiza, Formentera and associated islets. Genetic diversity within the endangered P. lilfordi has been well characterized, but P. pityusensis has not been studied in depth. Here, 2430 bp of mtDNA and 15 microsatellite loci were analysed from P. pityusensis populations from across its natural range. Two main genetic groupings were identified, although geographical structuring differed slightly between the mtDNA and the nuclear loci. In general, individuals from islets/islands adjacent to the main island of Ibiza were genetically distinct from those from Formentera and the associated Freus islands for both mtDNA and the nuclear loci. However, most individuals from the island of Ibiza were grouped with neighbouring islets/islands for nuclear loci, but with Formentera and Freus islands for the mitochondrial locus. A time-calibrated Bayesian tree was constructed for the principal mitochondrial lineages within the Balearics, using the multispecies coalescent model, and provided statistical support for divergence of the two main P. pityusensis lineages 0.111–0.295 Ma. This suggests a mid-late Pleistocene intraspecific divergence, compared with an early Pleistocene divergence in P. lilfordi, and postdates some major increases in sea level between 0.4 and 0.6 Ma, which may have flooded Formentera. The program IMa2 provided a posterior divergence time of 0.089–0.221 Ma, which was similar to the multispecies coalescent tree estimate. More significantly, it indicated low but asymmetric effective gene copy migration rates, with higher migration from Formentera to Ibiza populations. Our findings suggest that much of the present-day diversity may have originated from a late Pleistocene colonization of one island group from the other, followed by allopatric divergence of these populations. Subsequent gene flow between these insular groups seems likely to be explained by recent human introductions. Two evolutionary significant units can be defined for P. pityusensis but these units would need to exclude the populations that have been the subjects of recent admixture.

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There is a census of groups of lizards in some of the small islands of the Balearics, obtained by method of simplified successive suppression. The results are coherent with the observations in 50% of the cases. The minimum known group is of 6 ex. in the small islet of Fornol (Cabrera). The highest density corresponds to Escull Vermell in the group of Ses Bledes in Ibiza with 50 ex. in 350 m2 (1428 ex/Ha).

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Survey of the present known occurrences of population exposures within the Ibiza wall lizard (Podarcis pityusensis Boscà,1883). Probably more often than it has been documented in the past, lizards are transported with the help of men to other islands or islets where either no lizards live or which are inhabited by different subspecies. Therefore the mixing of populations is possible and the genetic barrier is broken which leads to complications in the taxonomy of these species. In some cases unfortunately such transported lizards have probably been described as different subspecies. In the future taxonomic studies of this specie the possible precence of such transported lizards within various populations should be given more attention.

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A brief report on the longevity in captivity of Podarcis pityusensis and Podarcis lilfordi.

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In the spring of 193o, the German zoologist Martin Eisentraut performed some field experiments with the Ibiza wall lizard Podarcis pityusensis (Boscá, 1883). When he found out that the small rocky island of Illa Negra de Llevant, located at the entrance to the port of Ibiza Town and close to the coast, seemed to have no lizard population of its own, he released a total of 5o specimens of the melanistic subspecies Podarcis pityusensis maluquerorum from the island of Bleda Plana. Although, these translocation experiments were published by Eisentraut (193o, 1949), they were obviously not known to all subsequent authors, and so the lizards encountered on the Illa Negra de Llevant in the period from 1979 onwards were always assigned to the nominate form Podarcis pityusensis pityusensis due to their similarity to the lizards of Ibiza. Previous investigations could not clarify whether the lizards of the Illa Negra de Llevant are descendants of the animals released by Eisentraut or whether they are specimens of a new introduction. With the results of our own investigations, we would like to contribute to solve the mystery of the lizards of the Illa Negra de Llevant.

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Some data concerning the reproduction in captivity of the melanistic subspecies of th Ibiza wall lizard Podarcis pityusensis maluquerorum are given. The data include information on the number of annual clutches, clutch and egg-size. Furthermore it is reported on th size and growth of the hatchlings.

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During several visits to th island Illiot de Sa Mesquida (Mesquida) the lizard Podarcis pityusensis pityusensis (Boscá 1883) was found in variable numbers Presumed is that the fluctuation within the lizard population is affected by the nesting colony of gulls (Larus cachinnans).