Factores que afectan a la supervivencia de los juveniles de la lagartija colilarga (Psammodromus algirus) : morfología, agresividad y uso del espacio

Se ha examinado, por medio de un estudio observacional y experimental, como influyen sobre la probabilidad de supervivencia,las siguientes variables: tamaño corporal, fecha de eclosión, comportamiento territorial, y características del dominio vital de los individuos juveniles de la lagartija colilarga (Psammodromus algirus). Los resultados muestran que una fecha de eclosión temprana, un mayor tamaño corporal y una condición corporal intermedia influyen positivamente en la probabilidad de supervivencia. Una mayor talla corporal es ventajoso en las peleas por los recursos y el espacio. Además, aquellos individuos más agresivos, poseían dominios vitales más grandes y de mejor calidad. Pero la agresividad tiene unos costes asociados, que se traducen en un retraso en el crecimiento corpora

Determinants of survival in juvenile Psammodromus algirus lizards

The study was supported by Dirección General de Investigación Científica y Técnica, Ministerio de Educación y Ciencia, project PB 97-1245, Spain (E.C.), and by The Swedish Natural Science Research Council (A.F.). E. Civantos was funded by a pre-doctoral grant from Ministerio de Educación y Ciencia, Spain.Theories posit that the relative mortality rate of adults and juveniles is a major determinant of population dynamics and life history evolution. Moreover, differential survival of pre-reproductive individuals may be an important source of variation in lifetime reproductive success, and characters that influence survival of juveniles are likely to be under strong selection. We examined survival from hatching to maturity in a natural population of Psammodromus algirus lizards using data from a capture-mark-recapture study. We found that mortality from hatching to maturity was high: only 8% of males and 14% of females that hatched in 1996 survived the entire study period until maturity in spring 1998. The probability of survival was 75% during both the first and second overwinter periods when lizards were inactive most of the time, and about 25% during their first spring to autumn activity season. Our analyses further revealed significant associations between survival and snout-vent length, body condition, sex and microhabitat use. However, the relationship between survival and morphological characters varied among time periods, presumably because the sources of mortality during the activity season were different from those during hibernation. The association between survival and body condition also varied within time periods, both between large and small individuals and between the two sexes. This suggests that the relative importance of different selective agents may change during the life of individuals and vary between males and females due to differences in body size and behaviour.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Non-lethal effects of predators on body growth and health state of juvenile lizards, Psammdromus algirus

Financial support was provided by the project MCI-CGL2008-02119/BOS and by an I3P contract to E. Civantos. Experiments were performed under license from the “Comunidad de Madrid” Environmental Agency.Predation risk does not necessarily increase predation rates because prey may be able to behave differentially to cope with higher predation risk. However, antipredatory behaviors may be costly, leading to negative, although non-lethal, effects of predators on prey. We examined in outdoor enclosures whether an experimental increase in predation pressure, which did not increase direct mortality, but forced individuals to increase antipredatory behaviors, may have significant non-lethal effects on body growth and health state of juvenile lizards, Psammodromus algirus. Simulated persistent predator attacks resulted in slower rates of body size growth and body mass gain of juvenile lizards, which may greatly affect their future survival. However, juvenile lizards were able to maintain their initial body condition and immune response regardless of predation risk level. Moreover, our data suggested that experience of lizards with their home range “environment” might allow them to compensate the negative effects of temporal high predation risk on body condition when predation risk subsequently decreased. Finally, juvenile lizards with greater immune responses showed smaller increments in body size, but larger increments in body mass and body condition, at the end of the control treatment. In contrast, there was no relationship between immunity and growth after the experimental treatment.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Immune function, parasitization and extended phenotypes in colour polymorphic pygmy grasshoppers

The study was financially supported by the Spanish Education and Culture Ministry (postdoctoral grant to EC), Swedish Natural Science Research Council and Swedish Research Council (AF), Växjö University and Kalmar University.Ecological and evolutionary consequences of host–parasite interactions have attracted considerable attention from evolutionary biologists. Previous studies have suggested that immune responsiveness may be genetically or developmentally linked with colour pattern, such that the evolution of animal colour patterns may be influenced by correlated responses to selection for parasite resistance. We studied interactions between the endoparasitic fly Leiophora innoxia (Meigen) (Diptera: Tachinidae) and its colour polymorphic pygmy grasshopper host Tetrix undulata (Sow.) (Orthoptera: Tetrigidae) to test for morph-specific differences in parasitization and immune defence, and host-induced variation in parasite phenotypes. Our results revealed that c. 2 and 30% of adult grasshoppers collected from the same natural population in two subsequent years, respectively were parasitized. Parasite prevalence was independent of host sex and colour morph. Pupae were larger if the parasite had developed in a female than in a male host, possibly reflecting host resource value or a physical constraint on larval growth imposed by host body size. Pupal size was also associated with host colour morph, with individuals that had developed in dark morphs being smaller at pupation compared to those that developed in paler morphs. However, immune defence, measured as the encapsulation response to a novel antigen, did not differ among individuals belonging to alternative colour morphs or sexes. Darker morphs warm up more quickly and prefer higher body temperatures than paler ones. Encapsulation was not influenced by maintenance temperature (15 vs. 30 °C), however, suggesting that indirect effects of coloration on parasite resistance mediated via differential body temperature are unlikely. The dependence of parasite body size on host colour morph may thus reflect plasticity of growth and development of the larvae in response to differential host body temperature, rather than variable host immune defence.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Habitat type influences parasite load in Algerian Psammodromus (Psammodromus algirus) lizards

Financial support was provided by the Ministerio de Economía e Innovación (grant MINECO-CGL2014-53523-P). E.C. was supported by the Portuguese Science and Technology Foundation (FCT) through postdoctoral grant SFRH/BPD/109182/2015.Understanding how habitat type and deterioration may affect parasitism is important in assessing the effects of human-induced environmental change on host–parasite dynamics. In this study, we examined inter-population differences in parasite load in the Mediterranean lizard Psammodromus algirus (Linnaeus, 1758). We analyzed prevalence and intensity of infection by blood parasites and ectoparasites in two populations separated by a 400 m elevational gradient and with different habitat types that also differed in the degree of human alteration. We also compared data obtained from the same populations 10 years later to assess whether there have been temporary changes in parasite loads. Results showed that prevalence and intensity of blood parasites were higher in the deteriorated lowland holm oak forest population than in the well-preserved upland oak forest. In contrast, the prevalence and intensity of infection by Ixodes Latreille, 1795 ticks was higher in the upland oak forest population. Individuals from the lowland population were in poorer condition. Intensities of infection by blood parasites and ectoparasites have decreased significantly from 2005–2006 to 2016 in both populations. Our results suggest that inter-population differences in parasite load may be explained by differences in habitat characteristics. This study contributes to the identification of ecosystems and habitats that are most sensitive to prevalence and intensity of infection by parasites.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Niche occupancy of two (congeneric) skinks in an islands environment

Among the scincid lizards inhabiting the Mediterranean region, the Ocellated skink (Chalcides ocellatus) and the little-known and endangered Chafarinas’ skink (Chalcides parallelus) co-occur in sympatry at the Chafarinas Islands (NW Africa). Although both species are present in the archipelago, C. ocellatus is spread in the three islands, but C. parallelus is present only in one island. What factors influence this distribution, and whether these two species show evidence for syntopy is unknown. In this study, we investigated spatial niche occupancy at the level of microhabitat of both skinks at the Chafarinas Islands. We tested for microhabitat differences between islands and then, we tested the null hypothesis of no differences between microhabitat used by each of these skink species and a set of locations chosen at random from the general habitat. Results showed that the distribution and abundance of available microhabitats were different among islands, thus each island has different spatial niches that may be important in distinguishing the areas occupied by these skinks. Results also revealed that C. ocellatus did not use available microhabitats at random, but preferentially selected particular microhabitats. However, C. parallelus used microhabitats according to their availability, although it showed some aspects of habitat selection similar to C. ocellatus. Our results showed that the inclusion of detailed microhabitat descriptors could be useful for understanding patterns of niche occupancy by these skinks species. Furthermore, to our knowledge this is the first study documenting the spatial niche selection of C. parallelus and provides novel ecological information that may be of major importance to develop management strategies that will help to conserve this endangered species.Ministerio de Ciencia, Innovación y UniversidadesOrganismo Autónomo de Parques Nacionales(España)Portuguese Science and Technology Foundation (FCT)Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Do skin pockets of lizards reduce the deleterious effects of ectoparasites? An experimental study with Psammodromus algirus

The work was supported by DGICYT projects PB 94-0067 and PB 94-0070-C02-01, and a DGICYT predoctoral grant to E. Civantos. Permission for this study was granted by Agencia de Medio Ambiente, Comunidad de Madrid (13/064959.2/95).Many species of lizards have skin invaginations that contain ectoparasites. These structures could concentrate ectoparasites and reduce their harmful effects, but experimental evidence supporting this hypothesis is largely lacking. We report here the first experimental test of this hypothesis which we conducted with the lacertid lizard Psammodromus algirus, a species that has a nuchal pocket on each side of the neck and is a regular intermediate host of the tick Ixodes ricinus. We manipulated circulating testosterone levels of males to increase tick infestation and blocked pockets to prevent tick attachment. When ticks had free access to pockets, ticks were attached mainly in pockets when tick load was low, but they were present in similar proportions in ears, pockets, and axillae in heavily parasited males. When tick pockets were blocked, infestation rates were comparable to those of unblocked lizards, but ticks were concentrated on the ears and in the axillae. The experimental group, with blocked pockets, was seen over a shorter period and in a smaller patch of habitat. This suggests that survival and home range were reduced. These data indicate that concentration of ticks in pockets may be beneficial for P. algirus and support the functional value of these structures.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Chemical ornaments of male lizards Psammodromus algirus may reveal their parasite load and health state to females

Financial support was provided by the Ministerio de Educación y Ciencia project CGL2005-00391/BOS, by an El Ventorrillo Consejo Superior de Investigaciones Científicas grant to L. Amo, and by an I3P contract to E. Civantos.Evidence for parasite-mediated sexual selection has been found in many species that use visual ornaments to attract females. However, in many animals, variation in female responses to scents of parasitized males suggests that parasitic infections might also affect information conveyed by pheromones (i.e., chemical ornaments). Thus, pheromones might also function in parasite-mediated sexual selection. We show here that female lizards Psammodromus algirus responded differently to femoral gland secretions of males according to the parasite load and health of these males. Scents of healthier males elicited more tongue flicks (a chemosensory behavior) by females, suggesting that these scents were more attractive. Chemical analyses showed that parasite load and the T-cell-mediated immune response were related to the variability in the proportions of some lipids in secretions of males. Further trials testing the chemosensory responses of females to chemical standards indicated that females actually discriminated the chemicals related to males’ health from other chemicals found in secretions. We suggest that these chemical ornaments may provide reliable information on the health and degree of parasitic infection of a male.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Comparative landscape genetics of pond‐breeding amphibians in Mediterranean temporal wetlands: The positive role of structural heterogeneity in promoting gene flow

Funding information: Secretaría de Estado de Investigación, Desarrollo e Innovación, Grant/AwardNumber: CGL2011-28300; Consejo Superior de Investigaciones Científicas of Spain (CSIC); European Social Fund (ESF); FCT,Grant/Award Number: SFRH/BD/90112/2012, SFRH/BPD/109182/2015; POPH-QREN; CSF; Spanish “Ramón y Cajal”, Grant/Award Number: RYC-2007-01668; Severo Ochoa, Grant/Award Number: SEV-2012-0262Comparative landscape genetics studies can provide key information to implement cost-effective conservation measures favouring a broad set of taxa. These studies are scarce, particularly in Mediterranean areas, which include diverse but threatened biological communities. Here, we focus on Mediterranean wetlands in central Iberia and perform a multi-level, comparative study of two endemic pond-breeding amphibians, a salamander (Pleurodeles waltl) and a toad (Pelobates cultripes). We genotyped 411 salamanders from 20 populations and 306 toads from 16 populations at 18 and 16 microsatellite loci, respectively, and identified major factors associated with population connectivity through the analysis of three sets of variables potentially affecting gene flow at increasingly finer levels of spatial resolution. Topographic, land use/cover, and remotely sensed vegetation/moisture indices were used to derive optimized resistance surfaces for the two species. We found contrasting patterns of genetic structure, with stronger, finer scale genetic differentiation in Pleurodeles waltl, and notable differences in the role of fine-scale patterns of heterogeneity in vegetation cover and water content in shaping patterns of regional genetic structure in the two species. Overall, our results suggest a positive role of structural heterogeneity in population connectivity in pond-breeding amphibians, with habitat patches of Mediterranean scrubland and open oak woodlands (“dehesas”) facilitating gene flow. Our study highlights the usefulness of remotely sensed continuous variables of land cover, vegetation and water content (e.g., NDVI, NDMI) in conservation-oriented studies aimed at identifying major drivers of population connectivity.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

A model-based framework for assessing the vulnerability of low dispersal vertebrates to landscape fragmentation under environmental change

João Gonçalves is financially supported by FCT (Portuguese Science Foundation) through PhD grant SFRH/BD/90112/2012. J.R. Vicente received support from the Portuguese Ministry of Education and Science and the European Social Fund, though the Portuguese Foundation of Science and Technology (FCT), under POPH – QREN – Typology 4.1. J. Honrado was supported by FCT and FEDER/COMPETE through project MOBIA (PTDC/AAC-AMB/114522/2009). Emilio Civantos was supported by Project “Biodiversity, Ecology and Global Change” co-financed by North Portugal Regional Operational Programme 2007/2013 (ON.2—O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).Environmental changes are driving rapid geographic shifts of suitable environmental conditions for species. These might survive by tracking those shifts, however successful responses will depend on the spatial distribution of suitable habitats (current and future) and on their connectivity. Most herptiles (i.e., amphibians and reptiles) have low dispersal abilities, and therefore herptiles are among the most vulnerable groups to environmental changes. Here we assessed the vulnerability of herptile species to future climate and land use changes in fragmented landscapes. We developed and tested a methodological approach combining the strengths of Species Distribution Models (SDMs) and of functional connectivity analysis. First, using SDMs we forecasted current and future distributions of potential suitable areas as well as range dynamics for four herptile species in Portugal. SDM forecasts for 2050 were obtained under two contrasting emission scenarios, translated into moderate (low-emissions scenario) or large (high-emissions scenario) changes in climate and land use conditions. Then, we calculated and analysed functional connectivity from areas projected to lose environmental suitability towards areas keeping suitable conditions. Landscape matrix resistance and barrier effects of the national motorway network were incorporated as the main sources of fragmentation. Potential suitable area was projected to decrease under future conditions for most test species, with the high-emissions scenario amplifying the losses or gains. Spatiotemporal patterns of connectivity between potentially suitable areas signalled the most important locations for maintaining linkages and migration corridors, as well as potential conflicts due to overlaps with the current motorway network. By integrating SDM projections with functional connectivity analysis, we were able to assess and map the vulnerability of distinct herptile species to isolation or extinction under environmental change scenarios. Our framework provides valuable information, with fairly low data requirements, for optimizing biodiversity management and mitigation efforts, aiming to reduce the complex and often synergistic negative impacts of multiple environmental change drivers. Implications for conservation planning and management are discussed from a global change adaptation perspective.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu