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Olivier Lourdais - One of the best experts on this subject based on the ideXlab platform.
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hybridization between a euro siberian Vipera berus and a para mediterranean viper v aspis at their contact zone in western france
Journal of Zoology, 2017Co-Authors: G Guiller, Olivier Lourdais, Sylvain UrsenbacherAbstract:Western European vipers are well-defined species with parapatric distributions that reflect contrasting thermal niches and climatic adaptations. Contact zones are usually narrow, coincide with steep ecological gradients and are associated with clear habitat segregation. Natural hybridization has been demonstrated between several species but has not been detected in others. The cold-adapted adder (V. berus, subgenus Pelias) is not known to hybridize with the warm-adapted aspic viper (V. aspis subgenus Vipera). For over 12 years, we have monitored sympatric populations of V. berus and V. aspis in western France where the two species exhibit very similar life cycles. We tested for possible hybridization because individuals with intermediate morphological traits have been reported in the past and were recently detected in the study population. Our results demonstrate that hybridization actually occurs and is directional since it involves females V. aspis viper and male V. berus in all analyzed cases. We discuss our results in the frame of previous findings on contact zones to evaluate in which conditions hybridization may occur.
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effects of mild wintering conditions on body mass and corticosterone levels in a temperate reptile the aspic viper Vipera aspis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Francois Brischoux, Olivier Lourdais, Andreaz Dupoue, Frederic AngelierAbstract:Abstract Temperate ectotherms are expected to benefit from climate change (e.g., increased activity time), but the impacts of climate warming during the winter have mostly been overlooked. Milder winters are expected to decrease body condition upon emergence, and thus to affect crucial life-history traits, such as survival and reproduction. Mild winter temperature could also trigger a state of chronic physiological stress due to inadequate thermal conditions that preclude both dormancy and activity. We tested these hypotheses on a typical temperate ectothermic vertebrate, the aspic viper ( Vipera aspis ). We simulated different wintering conditions for three groups of aspic vipers (cold: ~ 6 °C, mild: ~ 14 °C and no wintering: ~ 24 °C) during a one month long period. We found that mild wintering conditions induced a marked decrease in body condition, and provoked an alteration of some hormonal mechanisms involved in emergence. Such effects are likely to bear ultimate consequences on reproduction, and thus population persistence. We emphasize that future studies should incorporate the critical, albeit neglected, winter season when assessing the potential impacts of global changes on ectotherms.
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microclimate preferences correlate with contrasted evaporative water loss in parapatric vipers at their contact zone
Canadian Journal of Zoology, 2014Co-Authors: Olivier Lourdais, Michael Guillon, Gaetan Guiller, Dale F DenardoAbstract:Terrestrial ectotherms predominantly use behavioural means to thermoregulate and thereby optimize performances. However, thermoregulation can impart physiological challenges to other critical processes such as water balance by increasing evaporative water loss (EWL). Like thermoregulation, water balance is influenced by both external factors (e.g., microhabitat and environmental constraints) and endogenous traits (e.g., evaporative water loss rates, dehydration tolerance). Although thermoregulation and water balance are tightly linked, the role of water balance is often overlooked when evaluating species climatic adaptation and response to global warming. We studied two congeneric viperid species (the Aspic Viper, Vipera aspis (L., 1758), and the Common Viper, Vipera berus (L., 1758)) with contrasted climatic affinities (south European versus boreal, respectively). These parapatric species are syntopic in narrow contact zones where microhabitat partitioning has been reported. We compared total EWL and cut...
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climate affects embryonic development in a viviparous snake Vipera aspis
Oikos, 2004Co-Authors: Olivier Lourdais, Michael Guillon, Richard Shine, Xavier Bonnet, Guy NaulleauAbstract:Climatic conditions during embryonic development can exert profound and long-term effects on many types of organisms, but most previous research on this topic has focussed on endothermic vertebrates (birds and mammals). Although viviparity in ectothermic taxa allows the reproducing female to buffer ambient thermal variation for her developing offspring, even an actively thermoregulating female may be unable to provide optimal incubation regimes in severe weather conditions. We examined the extent to which fluctuations in natural thermal conditions during pregnancy affect reproduction in a temperate viviparous snake, the aspic viper (Vipera aspis). Data gathered from a long term field study demonstrated that ambient thermal conditions influenced (1) female body temperatures and (2) gestation length, embryo viability, and offspring phenotypes. Interestingly, thermal conditions during each of the three months of gestation affected different aspects of reproduction. Hotter weather early in gestation (June) increased ventral scale counts (=number of body segments) of neonates; hotter weather mid-gestation (July) hastened development and thus the date of parturition; and hotter weather late in gestation (August) reduced the incidence of stillborn neonates. The population that we studied is close to the northern limit of the species’ range, and embryonic thermal requirements may prevent Vipera aspis from extending into cooler conditions further north.
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gestation thermoregulation and metabolism in a viviparous snake Vipera aspis evidence for fecundity independent costs
Physiological and Biochemical Zoology, 2003Co-Authors: Mitchell Ladyman, Olivier Lourdais, Xavier Bonnet, Don Bradshaw, Guy NaulleauAbstract:Abstract Oxygen consumption of gestating Aspic vipers, Vipera aspis (L.), was strongly dependent on body temperature and mass. Temperature‐controlled, mass‐independent oxygen consumption did not differ between pregnant and nonpregnant females. Maternal metabolism was not influenced during early gestation by the number of embryos carried but was weakly influenced during late gestation. These results differ from previous investigations that show an increase in mass‐independent oxygen consumption in reproductive females relative to nonreproductive females and a positive relationship between metabolism and litter size. These data also conflict with published field data on V. aspis that show a strong metabolic cost associated with reproduction. We propose that, under controlled conditions (i.e., females exposed to precise ambient temperatures), following the mobilisation of resources to create follicles (i.e., vitellogenesis), early gestation per se may not be an energetically expensive period in reproduction....
Oleksandr Zinenko - One of the best experts on this subject based on the ideXlab platform.
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Hybrid origin of European Vipers (Vipera magnifica and Vipera orlovi) from the Caucasus determined using genomic scale DNA markers
BMC Evolutionary Biology, 2016Co-Authors: Oleksandr Zinenko, Michael G Sovic, Ulrich Joger, H. Lisle GibbsAbstract:Background Studying patterns of introgression can illuminate the role of hybridization in speciation, and help guide decisions relevant to the conservation of rare taxa. Vipera magnifica and Vipera orlovi are small vipers that have high conservation status due to their rarity and restricted distributions in an area of the Caucasus region where two other related species are present – V. kaznakovi and V. renardi. Despite numerous observations of hybridization between different species of small vipers, and the potential of a hybrid origin for V. magnifica and V. orlovi based on their distribution with respect to V. kaznakovi and V. renardi , hypotheses of a hybrid origin have not been formally tested. Here we generate genomic-scale data by performing next generation sequencing of double digest restriction-site associated DNA libraries, and use these multilocus data to test whether these two species are of hybrid origin. Results We generated over nine hundred loci for 38 specimens of six taxa, and analysed the dataset using Bayesian clustering and multivariate methods, as well as Patterson D-statistics, which can distinguish between incomplete lineage sorting and introgression as explanations for shared polymorphism. The results demonstrate a pattern of historical admixture in the two purported hybrids that is consistent with past gene flow from V. renardi into V. kaznakovi . The average admixture proportion in individuals was low (6.39 %) in the case of V. magnifica , but was higher in V. orlovi (19.02 %). We also show that the specific individual samples used in D-statistic tests can have a significant impact on inferences regarding the magnitude of introgression, suggesting the importance of including multiple individuals in these analyses. Conclusions Our results support the conclusion that both V. orlovi and V. magnifica had formed through a hybridization event between V. kaznakovi and V. renardi . Given a low proportion of admixture and absence of clear ecological and morphological differences V. magnifica should be treated as a marginal population of V. kaznakovi . Further studies that include analyses of ecological segregation of V. orlovi from parental taxa and search for evolutionary consequences of hybridisation would clarify if V. orlovi is a distinct hybrid species. Until this we recommend preserving the current taxonomy and protection status of V. orlovi .
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hybrid origin of european vipers Vipera magnifica and Vipera orlovi from the caucasus determined using genomic scale dna markers
BMC Evolutionary Biology, 2016Co-Authors: Oleksandr Zinenko, Michael G Sovic, Ulrich Joger, Lisle H GibbsAbstract:Background Studying patterns of introgression can illuminate the role of hybridization in speciation, and help guide decisions relevant to the conservation of rare taxa. Vipera magnifica and Vipera orlovi are small vipers that have high conservation status due to their rarity and restricted distributions in an area of the Caucasus region where two other related species are present – V. kaznakovi and V. renardi. Despite numerous observations of hybridization between different species of small vipers, and the potential of a hybrid origin for V. magnifica and V. orlovi based on their distribution with respect to V. kaznakovi and V. renardi, hypotheses of a hybrid origin have not been formally tested. Here we generate genomic-scale data by performing next generation sequencing of double digest restriction-site associated DNA libraries, and use these multilocus data to test whether these two species are of hybrid origin.
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mitochondrial phylogeny shows multiple independent ecological transitions and northern dispersion despite of pleistocene glaciations in meadow and steppe vipers Vipera ursinii and Vipera renardi
Molecular Phylogenetics and Evolution, 2015Co-Authors: Oleksandr Zinenko, Tatiana Kotenko, Nikolaus Stumpel, Lyudmila Mazanaeva, Andrey G Bakiev, Konstantin Shiryaev, Aleksey Pavlov, Oleg Kukushkin, Yury ChikinAbstract:The phylogeny and historical demography of small Eurasian vipers of the Vipera ursinii and V. renardi complexes were studied using mitochondrial DNA sequences analysed with Bayesian inference, Maximum Likelihood and Maximum Parsimony approaches, and mismatch distributions. Diversification in the group resulted from an initial dispersion in the later Pliocene – Pleistocene in two directions: north-westwards via the Balkans (V. ursinii complex) and north-eastwards from Asia Minor via the Caucasus (V. renardi complex). An independent, comparatively recent transition occurred from montane habitats to lowland grasslands in different mitochondrial lineages during the Late Pleistocene, when representatives of the both complexes had reached lowland steppes to the north. Effective population size showed clear signs of rapid growth in eastern V. renardi, triggered by colonization of vast lowland steppes, but in western V. ursinii complex grew during the Last Glaciation and experienced stabilization in Holocene. Expansion and population growth in lowland lineages of V. renardi was not strongly affected by Pleistocene climatic oscillations, when cold, dry conditions could have favoured species living in open grasslands. The high diversity of closely related haplotypes in the Caucasus and Tien-Shan could have resulted from repetitive expansion-constriction-isolation events in montane regions during Pleistocene climate fluctuations. The mitochondrial phylogeny pattern conflicts with the current taxonomy.
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distribution and morphological variation of Vipera berus nikolskii vedmederja grubant et rudaeva 1986 in western ukraine the republic of moldova and romania
Amphibia-reptilia, 2010Co-Authors: Oleksandr Zinenko, Vladimir ţurcanu, Alexandru StrugariuAbstract:Morphological variation of vipers of the Vipera berus complex in Eastern Romania, the Republic of Moldova and Western and Central Ukraine was studied using multivariate statistics. Discriminant analysis, based on ten meristic characters in 89.7% of cases (males) and in 92.0% cases (females), was able to separate reference samples of subspecies Vipera berus berus and Vipera berus nikolskii and was conducted to classify snakes from the studied territory. According to these results, V. b. nikolskii inhabits the broad-leaved forests in the forest-steppe zone in the Republic of Moldova, the hilly part of Eastern Romania and Central Ukraine. Specimens from a contact zone between V. b. berus and V. b. nikolskii have intermediate morphology and, thus, could represent the result of introgression. Populations of the Nikolsky's viper from the western part of its range combine high level of morphological differentiation from V. b. berus with the presence of non-black specimens and even include populations without melanistic specimens, previously thought not to occur in this taxon. A morphological description of the largest samples is given and determination of V. b. nikolskii is discussed.
Xavier Bonnet - One of the best experts on this subject based on the ideXlab platform.
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impact of cool versus warm temperatures on gestation in the aspic viper Vipera aspis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2013Co-Authors: Catherine Louise Michel, Jeanhenri Pastore, Xavier BonnetAbstract:Abstract Previous experimental data suggested that digestion and growth rates are not impaired under cool constant temperature (23 °C) in a viviparous snake ( Vipera aspis ). These results challenged the widespread notion that both elevated temperatures (e.g. 30 °C) and temperature fluctuations are required for digestion and growth in temperate climate reptiles. Here, we investigated the impact of constant cool temperatures on another physiological performance that is crucial to population persistence: gestation. At the time when reproductive females were midway through vitellogenesis, we placed ten reproductive and two non-reproductive female aspic vipers at each of two contrasted constant temperature conditions: cool (23 °C) versus warm (28 °C). Sixty percent of the females placed at 28 °C gave birth to healthy offspring, suggesting that constant warm body temperatures were compatible with normal offspring production. Conversely, none of the cool females gave birth to healthy offspring. A blister disease affected exclusively cool pregnant females. Apparently, the combination of cool temperatures plus gestation was too challenging for such females. Our results suggest that reproduction is more thermally sensitive than digestion or growth, indeed gestation faltered under moderately cool thermal constraints. This sensitivity could be a crucial factor determining the capacity of this species to colonize different habitats.
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climate affects embryonic development in a viviparous snake Vipera aspis
Oikos, 2004Co-Authors: Olivier Lourdais, Michael Guillon, Richard Shine, Xavier Bonnet, Guy NaulleauAbstract:Climatic conditions during embryonic development can exert profound and long-term effects on many types of organisms, but most previous research on this topic has focussed on endothermic vertebrates (birds and mammals). Although viviparity in ectothermic taxa allows the reproducing female to buffer ambient thermal variation for her developing offspring, even an actively thermoregulating female may be unable to provide optimal incubation regimes in severe weather conditions. We examined the extent to which fluctuations in natural thermal conditions during pregnancy affect reproduction in a temperate viviparous snake, the aspic viper (Vipera aspis). Data gathered from a long term field study demonstrated that ambient thermal conditions influenced (1) female body temperatures and (2) gestation length, embryo viability, and offspring phenotypes. Interestingly, thermal conditions during each of the three months of gestation affected different aspects of reproduction. Hotter weather early in gestation (June) increased ventral scale counts (=number of body segments) of neonates; hotter weather mid-gestation (July) hastened development and thus the date of parturition; and hotter weather late in gestation (August) reduced the incidence of stillborn neonates. The population that we studied is close to the northern limit of the species’ range, and embryonic thermal requirements may prevent Vipera aspis from extending into cooler conditions further north.
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gestation thermoregulation and metabolism in a viviparous snake Vipera aspis evidence for fecundity independent costs
Physiological and Biochemical Zoology, 2003Co-Authors: Mitchell Ladyman, Olivier Lourdais, Xavier Bonnet, Don Bradshaw, Guy NaulleauAbstract:Abstract Oxygen consumption of gestating Aspic vipers, Vipera aspis (L.), was strongly dependent on body temperature and mass. Temperature‐controlled, mass‐independent oxygen consumption did not differ between pregnant and nonpregnant females. Maternal metabolism was not influenced during early gestation by the number of embryos carried but was weakly influenced during late gestation. These results differ from previous investigations that show an increase in mass‐independent oxygen consumption in reproductive females relative to nonreproductive females and a positive relationship between metabolism and litter size. These data also conflict with published field data on V. aspis that show a strong metabolic cost associated with reproduction. We propose that, under controlled conditions (i.e., females exposed to precise ambient temperatures), following the mobilisation of resources to create follicles (i.e., vitellogenesis), early gestation per se may not be an energetically expensive period in reproduction....
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when does a reproducing female viper Vipera aspis decide on her litter size
Journal of Zoology, 2003Co-Authors: Olivier Lourdais, Richard Shine, Xavier Bonnet, Emily N TaylorAbstract:Some organisms rely on stored energy to fuel reproductive expenditure (capital breeders) whereas others use energy gained during the reproductive bout itself (income breeders). Most species occupy intermediate positions on this continuum, but few experimental data are available on the timescale over which food intake can affect fecundity. Mark–recapture studies of free-ranging female aspic vipers Vipera aspis have suggested that reproductive output relies not only on the energy in fat bodies accumulated in previous years, but also on food intake immediately before ovulation. A simple experiment was conducted to test this hypothesis, maintaining female snakes in captivity throughout the vitellogenic period and controlling their food intake. The energy input of a female strongly influenced the amount of mass that she gained and the number of ova that she ovulated. Multiple regression showed that litter size in these snakes was affected both by maternal body condition in early spring (an indicator of foraging success over previous years) and by food intake in the spring before ovulation. Our experimental data thus reinforce the results of descriptive studies on free-ranging snakes, and emphasize the flexibility of energy allocation patterns among vipers. Reproducing female vipers may combine energy from ‘capital’ and ‘income’ to maximize their litter sizes in the face of fluctuating levels of prey abundance.
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fat is sexy for females but not males the influence of body reserves on reproduction in snakes Vipera aspis
Hormones and Behavior, 2002Co-Authors: Fabien Aubret, Xavier Bonnet, Richard Shine, Olivier LourdaisAbstract:Reproduction is energetically expensive for both sexes, but the magnitude of expenditure and its relationship to reproductive success differ fundamentally between males and females. Males allocate relatively little to gamete production and, thus, can reproduce successfully with only minor energy investment. In contrast, females of many species experience high fecundity-independent costs of reproduction (such as migration to nesting sites), so they need to amass substantial energy reserves before initiating reproductive activity. Thus, we expect that the relationship between energy reserves and the intensity of reproductive behavior involves a threshold effect in females, but a gradual (or no) effect in males. We tested this prediction using captive vipers (Vipera aspis), dividing both males and females into groups of high versus low body condition. Snakes from each group were placed together and observed for reproductive behavior; sex-steroid levels were also measured. As predicted, females in below-average body condition had very low estradiol levels and did not show sexual receptivity, whereas males of all body condition indices had significant testosterone levels and displayed active courtship. Testosterone levels and courtship intensity increased gradually (i.e., no step function) with body condition in males, but high estradiol levels and sexual receptivity were seen only in females with body reserves above a critical threshold.
Roderich D. Süssmuth - One of the best experts on this subject based on the ideXlab platform.
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extended snake cenomics by top down in source decay investigating the newly discovered anatolian meadow viper subspecies Vipera anatolica senliki
Journal of Proteome Research, 2020Co-Authors: Benjamin-florian Hempel, Maik Damm, Bayram Göçmen, Mert Karış, Ayse Nalbantsoy, Manjunatha R Kini, Roderich D. SüssmuthAbstract:Herein, we report on the venom proteome of Vipera anatolica senliki, a recently discovered and hitherto unexplored subspecies of the critically endangered Anatolian meadow viper endemic to the Anta...
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Comparative Venomics of the Vipera ammodytes transcaucasiana and Vipera ammodytes montandoni from Turkey Provides Insights into Kinship
Toxins, 2018Co-Authors: Benjamin-florian Hempel, Maik Damm, Bayram Göçmen, Mert Karış, Mehmet Anıl Oğuz, Ayse Nalbantsoy, Roderich D. SüssmuthAbstract:The Nose-horned Viper (Vipera ammodytes) is one of the most widespread and venomous snakes in Europe, which causes high frequent snakebite accidents. The first comprehensive venom characterization of the regional endemic Transcaucasian Nose-horned Viper (Vipera ammodytes transcaucasiana) and the Transdanubian Sand Viper (Vipera ammodytes montandoni) is reported employing a combination of intact mass profiling and bottom-up proteomics. The bottom-up analysis of both subspecies identified the major snake protein families of viper venoms. Furthermore, intact mass profiling revealed the presence of two tripeptidic metalloprotease inhibitors and their precursors. While previous reports applied multivariate analysis techniques to clarify the taxonomic status of the subspecies, an accurate classification of Vipera ammodytes transcaucasiana is still part of the ongoing research. The comparative analysis of the viper venoms on the proteome level reveals a close relationship between the Vipera ammodytes subspecies, which could be considered to clarify the classification of the Transcaucasian Nose-horned Viper. However, the slightly different ratio of some venom components could be indicating interspecific variations of the two studied subspecies or intraspecies alternations based on small sample size. Additionally, we performed a bioactivity screening with the crude venoms against several human cancerous and non-cancerous cell lines, which showed interesting results against a human breast adenocarcinoma epithelial cell line. Several fractions of Vipera a. transcaucasiana demonstrated a strong cytotoxic effect on triple negative MDA MB 231 breast cancer cells.
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mass spectrometry guided venom profiling and bioactivity screening of the anatolian meadow viper Vipera anatolica
Toxicon, 2015Co-Authors: Bayram Göçmen, Ayse Nalbantsoy, Paul Heiss, Daniel Petras, Roderich D. SüssmuthAbstract:This contribution reports on the first characterization of the venom proteome and the bioactivity screening of Vipera anatolica, the Anatolian Meadow Viper. The crude venom as well as an isolated dimeric disintegrin showed remarkable cytotoxic activity against glioblastoma cells. Due to the rare occurrence and the small size of this species only little amount of venom was available, which was profiled by means of a combination of bottom-up and top-down mass spectrometry. From this analysis we identified snake venom metalloproteases, cysteine-rich secretory protein isoforms, a metalloprotease inhibitor, several type A2 phospholipases, disintegrins, a snake venom serine protease, a C-type lectin and a Kunitz-type protease inhibitor. Furthermore, we detected several isoforms of above mentioned proteins as well as previously unknown proteins, indicating an extensive complexity of the venom which would have remained undetected with conventional venomic approaches.
Jose Carlos Brito - One of the best experts on this subject based on the ideXlab platform.
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inferring evolutionary scenarios with geostatistics and geographical information systems for the viperid snakes Vipera latastei and Vipera monticola
Biological Journal of The Linnean Society, 2008Co-Authors: Jose Carlos Brito, Juan M Pleguezuelos, Xavier Santos, Neftali SilleroAbstract:The present study aimed to infer evolutionary scenarios for Vipera latastei and Vipera monticola in the Iberian Peninsula and the Maghreb through the identification of spatial patterns in morphological character variation and biogeographic patterns in morphological variability distribution. Ten morphological traits from 630 vipers were analysed with geostatistic and ecological niche modelling in a geographical information system. Interpolation by Kriging was used to generate surfaces of morphological variation, which were combined with spatial principal components analysis (SPCA). Putative morphological differentiated groups generated by SPCA maps were tested with discriminant function analysis (DFA). Maximum entropy modelling and nine environmental variables were used to identify factors limiting the distribution of groups and areas for their potential occurrence. Groups supported by DFA were: Western Iberia, Eastern Iberia, Rif plus Middle Atlas, Algeria, and High Atlas. Their distribution is influenced by common environmental factors such as precipitation. Areas of probable sympatry between Iberian groups matched the morphological clines observed by geostatistics tools. Geographic variation patterns in V. latastei-monticola are probably due to vicariant separation of Iberian and African populations during the opening of the Strait of Gibraltar, and population refugia during the Quaternary glaciations with secondary contact. The taxonomic status of northern Morocco and Algerian groups should be further investigated. We conclude that geostatistics and niche-modelling tools are adequate to infer morphological variability across wide geographic ranges of species. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 790–806.
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gis based niche models identify environmental correlates sustaining a contact zone between three species of european vipers
Diversity and Distributions, 2008Co-Authors: Fernando Martinezfreiria, Neftali Sillero, Miguel Lizana, Jose Carlos BritoAbstract:The current range of European vipers is mostly parapatric but local-scale allopatric distribution is common and few cases of sympatry are known. In the High Course of Ebro River, northern Spain, there is a contact zone between Vipera aspis, V. latastei, and V. seoanei. Sympatry was detected between aspis and latastei and also specimens with intermediate morphological traits. Presence-data at a local scale (1 x 1 km) and ecological niche-based models manipulated in a GIS were used to (1) identify how environmental factors correlate with the distribution of the three vipers and with the location of the sympatry area, and (2) identify potential areas for viper occurrence and sympatry. Ensemble for casting with 10 Maximum Entropy models identified a mixture of topographical (altitude, slope), climatic (precipitation, evapotranspiration, and minimum and maximum temperature), and habitat factors (land cover) as predictors for viper occurrence. Similar predicted probabilities according to the variation of some environmental factors (indicating probable sympatry) were observed only for aspis-latastei and aspis-seoanei. In fact, areas of probable occurrence of vipers were generally allopatric but probable sympatry between vipers was identified for aspis-latastei in 76 UTM 1 x 1 km squares, for aspis-seoanei in 23 squares, and latastei-seoanei in two squares. Environmental factors correlate with the location of this contact zone by shaping the species range: some enhance spatial exclusion and constrain distribution to spatially non-overlapping ranges, while others allow contact between species. The distribution in the contact zone apparently results from the balance between the pressures exerted by the different environmental factors and in the sympatry area probably by interspecific competition. Further ecological and genetical data are needed to evaluate the dynamics of the probable hybrid zone. GIS and niche-modelling tools proved to be powerful tools to identify environmental factors sustaining the location of contact zones.
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variation in the diet of the lataste s viper Vipera latastei in the iberian peninsula seasonal sexual and size related effects
Animal Biology, 2007Co-Authors: Juan M Pleguezuelos, Jose Carlos Brito, Soumia Fahd, Xavier Santos, Gustavo A Llorente, Xavier ParelladaAbstract:Several life-history traits may increase vulnerability of species to extinction. Among snakes, ambush predation and dietary specialisation are factors that increase this vulnerability. European viper species, genus Vipera, display such traits and are categorised as endangered in several parts of its range. For their conservation management, a deeper knowledge of their ecology and habitat use is highly relevant. One of the species with less ecological data is the Lataste's viper Vipera latastei, a species which lives in the Iberian Peninsula and northwestern Africa. Here, we describe its diet based on the analysis of gut content of 435 museum specimens plus nine bibliographic data from the entire Iberian range. The species showed seasonal and ontogenetic shift in diet but no sexual variations. Feeding activity (percentage of vipers with prey) was low in accordance with its ambush predation tactics, being lower in spring than in summer and autumn. Prey spectrum included two main (reptiles and small mammals), and three sporadic, types of prey (arthropods, amphibians and birds). The consumption of reptiles and mammals was seasonal; the former decreased in occurrence from spring to autumn, whereas the latter showed an opposite pattern. There was an ontogenetic shift in the diet: juveniles fed mainly on reptiles and arthropods, whereas adult vipers progressively substitute this prey with insectivores, and the largest vipers primarily foraged on rodents and birds. Our results suggest that the seasonal variation in prey type was related to prey availability, whereas the ontogenetic shift was linked to gape limitation. The apparently wide prey spectrum of V. latastei must therefore be examined, taking into account that there are seasonal and ontogenetic dietary variations as well as geographic differences, the latter probably driven by climatic contrasts into the Iberian Peninsula. This new data of the endangered Iberian V. latastei can aid the effective conservation management of this species.
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inferring habitat suitability areas with ecological modelling techniques and gis a contribution to assess the conservation status of Vipera latastei
Biological Conservation, 2006Co-Authors: Neftali Sillero, Jose Carlos Brito, Juan M Pleguezuelos, Soumia Fahd, Xavier Santos, Gustavo A Llorente, Xavier ParelladaAbstract:Some snakes are highly vulnerable to extinction due to several life history traits. However, the elusive behavior and secretive habits of some widespread species constrain the collection of demographic and ecological data necessary for the identification of extinction-prone species. In this scenario, the enhancement of ecological modelling techniques in Geographical Information Systems (GIS) is providing researchers with robust tools to apply to such species. This study has identified the environmental factors that limit the current distribution of Vipera latastei, a species with secretive behavior, and has evaluated how human activities affect its current conservation status, identifying areas of best habitat suitability in the Iberian Peninsula. Ecological-niche factor analysis (ENFA) indicated low marginality (0.299) and high tolerance (0.887) scores, suggesting strong tendency for the species to live in average conditions throughout the study area and to inhabit any of the environmental conditions. The analysis also revealed that this viper tends to select particular Mediterranean habitats, although topographic factors (altitude and slope) were the major environmental constraints for the Iberian distribution pattern of the species. The presence of other parapatric viper species in the north of the Iberian Peninsula (V. aspis and V. seoanei) and two human-related variables (landscape transformation and human density) also had a negative relation with the occurrence of V. latastei. All factors can explain its absence in northern Iberia and its fragmented distribution as currently is found mostly in mountains and relatively undisturbed low-altitude areas. The historical destruction and alteration of natural Mediterranean habitats and several life-history traits of the species contribute to its vulnerability to extinction. The ENFA analysis proved to be an outstanding method to evaluate the factors that limit the distribution range of secretive and widespread species such as V. latastei, updating evaluation of their conservation status.
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morphological variability of the lataste s viper Vipera latastei and the atlas dwarf viper Vipera monticola patterns of biogeographical distribution and taxonomy
Amphibia-reptilia, 2006Co-Authors: Jose Carlos Brito, Juan M Pleguezuelos, Soumia Fahd, Xavier Santos, Gustavo A Llorente, Xavier ParelladaAbstract:The Lataste's viper Vipera latastei is a medium-sized viper distributed throughout almost the entire Iberian Peninsula and north-west of Africa. Former morphological studies noted the existence of two subspecies, V. l. gaditana and V. l. latastei, as well as a full species, V. monticola, in the High Atlas, corresponding to the prior overall range described for V. latastei. However, some results remained unclear in these former studies, e.g. the specific status of the Medium Atlas populations, the intra-subspecific differences in V. l. gaditana and, the true status of some isolated populations of the northern range. For this reason, 45 morphological characters were analysed in 672 preserved specimens covering the entire range. Categorical Principal Components Analysis (CATPCA) and Discriminant Function Analysis (DFA) were used to assess geographic variability, treating specimens individually or assigning them ap riorito groups, respectively. Geographic groups were established according to the origin of specimens in isolated areas of mountain chains. As the percentage of correct assignment was low in DFA, initial groups were combined to maximize the percentage. The results from the multivariate analysis suggest morphological differentiation between populations. Some variables accounted for geographic variability: e.g. rows of dorsal scales at mid-body are taxonomically stable and clearly separate the African populations; and number of ventral scales showed a clinal variation from 126 to 143 ventrals in extreme populations. The three African groups manifested clear morphological differences, and especially specimens from the High Atlas (V. monticola) and Alger. On the contrary, a large number of initial Iberian groups were merged because of the low scores in the correct classification. The final groups showed a vast central area with low morphological differentiation as well as isolated populations in the NW, NE and SW Iberian Peninsula. This conclusion matches well with allopatric speciation processes during the Quaternary ice ages, which contributed to the contraction/expansion of range, isolation events, and peripheral population refugia. Morphological differentiation in external characters of V. latastei exhibited similar results with respect to V. aspis and V. ammodytes, the vipers occupying other southern European peninsulas. Molecular markers will contribute to elucidate the relationships between V. latastei populations and the history of colonisation across the Strait of Gibraltar.
