Do sexual differences in life strategies make male lizards more susceptible to parasite infection?

Female and male hosts may maximise their fitness by evolving different strategies to compensate for the costs of parasite infections. The resulting sexual dimorphism might be apparent in differential relationships between parasite load and body condition, potentially reflecting differences in energy allocation to anti-parasitic defences. For example, male lacertids with high body condition may produce many offspring while being intensely parasitised. In contrast, female lacertids may show a different outcome of the trade-offs between body condition and immunity, aiming to better protect themselves from the harm of parasites. We predicted that females would have fewer parasites than males and a lower body condition across parasitaemia levels because they would invest resources in parasite defence to mitigate the costs of infection. In contrast, the male strategy to maximise access to females would imply some level of parasite tolerance and, thus, higher parasitaemia. We analysed the relationship between the body condition of lizards and the parasitemias of Karyolysus and Schellackia, two genera of blood parasites with different phylogenetic origins, in 565 females and 899 males belonging to 10 species of the Lacertidae (Squamata). These lizards were sampled over a period of 12 years across 34 sampling sites in southwestern Europe. The results concerning the Karyolysus infections were consistent with the predictions, with males having similar body condition across parasitaemia levels even though they had higher infection intensities than females. On the other hand, females with higher levels of Karyolysus parasitaemia had lower body condition. This is consistent with the prediction that different life strategies of male and female lacertids can explain the infection patterns of Karyolysus. In contrast, the parasitaemia of Schellackia was consistently low in both male and female hosts, with no significant effect on the body condition of lizards. This suggests that lizards of both sexes maintain this parasite below a pathogenic threshold.

Los machos y hembras pueden maximizar su eficacia biológica mediante la evolución diferencial de estrategias que compensen los costes asociados con las infecciones parasitarias. Por ejemplo, los machos con una alta condición corporal pueden producir muchas crías aun estando altamente parasitados. Mientras que es común que las hembras inviertan más energía en protegerse frente a los parásitos, lo que podría comprometer el mantenimiento de su condición corporal. Nuestra hipótesis es que las diferencias sexuales en la asignación de energía pueden quedar de manifiesto al analizar la relación entre la intensidad de infección con la condición corporal. También esperamos que las hembras tengan menos parásitos que los machos y que su condición corporal esté correlacionada negativamente con su carga parasitaria. Por el contrario, esperamos que los machos tengan más parásitos en parte porque su estrategia implicaría cierto nivel de tolerancia si con ello pueden incrementar su inversión reproductiva. Hemos analizado la relación entre la condición corporal y las parasitemias de Schellackia y Karyolysus, dos parásitos sanguíneos, en 565 hembras y 899 machos de 10 especies de la familia Lacertidae (Squamata) durante 12 años en 34 localidades en el suroeste de Europa. El patrón para Karyolysus fue coherente con las predicciones, ya que la condición corporal de los machos no se correlacionó con su parasitemia, a pesar de que estas fueron mayores que en las hembras. Mientras que la relación fue negativa en las hembras. Por lo que el patrón de infección de Karyolysus concuerda con las diferentes estrategias de inversión energética en machos y hembras. Sin embargo, en el caso de Schellackia las parasitemias fueron más bajas en hospedadores de ambos sexos y su parasitemia no se correlacionó con la condición corporal. Este resultado sugiere que Schellackia es mantenido en umbrales subpatogénicos.

Ecological determinants of prevalence of the male-killing bacterium Arsenophonus nasoniae.

Male-killing bacteria are found in a broad range of arthropods. Arsenophonus nasoniae is a male-killing bacterium, causing a 80% reduction of the male progeny in infected Nasonia vitripennis wasps. Although the discovery of A. nasoniae dates from the early 80's, knowledge about the biology and ecology of this endosymbiont is still scarce. One of these poorly studied features is the ecological factors underlying A. nasoniae incidence on its Nasonia spp. hosts in different geographical locations. Here, we studied the prevalence of A. nasoniae in Iberian wild populations of its host N. vitripennis. This wasp species is a common parasitoid of the blowfly Protocalliphora azurea pupae, which in turn is a parasite of hole-nesting birds, such as the blue tit (Cyanistes caeruleus). We also examined the effects of bird rearing conditions on the prevalence of A. nasoniae through a brood size manipulation experiment (creating enlarged, control and reduced broods). Both the wasp and bacterium presence were tested through PCR assays in blowfly pupae. We found A. nasoniae in almost half (47%) of nests containing blowflies parasitized by N. vitripennis. The prevalence of A. nasoniae was similar in the two geographical areas examined (central Portugal and southeastern Spain) and the probability of infection by A. nasoniae was independent of the number of blowfly pupae in the nest. Experimental manipulation of brood size did not affect the prevalence of A. nasoniae nor the prevalence of its host, N. vitripennis. These results suggest that the incidence of A. nasoniae in natural populations of N. vitripennis is high in the Iberian Peninsula, and the infestation frequency of nests by N. vitripennis carrying A. nasoniae is spatially stable in this geographical region independently of bird rearing conditions.

Seasonal and altitudinal variation in dorsal skin reflectance and thermic rates in a high-altitude montane lizard.

Temperature is one of the most important factors in the life histories of ectotherms, as body temperature has an undeniable effect on growth, activity, and reproduction. Lizards have a wide variety of strategies to acquire and maintain body temperature in an optimal range. The "Thermal Melanism Hypothesis" proposes that individuals with lower skin reflectance can heat up faster as a result of absorbing more solar radiation compared to lighter conspecifics. Therefore, having a darker coloration might be advantageous in cold habitats. Dorsal skin reflectance has been found to change rapidly with body temperature in several lizard species, and it can also vary over longer, seasonal time scales. These variations may be important in thermoregulation, especially in lizards that inhabit areas with a large temperature variation during the year. Here, we study how dorsal reflectance fluctuates with body temperature and varies among seasons. We compared dorsal skin reflectance at three body temperature treatments, and measured thermal rates (i.e., heat and cool rate, thermic lapse, and net heat gain) by elevation (2500-4100 m) and seasons (spring, summer, and autumn) in the mesquite lizard, Sceloporus grammicus. Our results show that lizards were darker at high elevations and during the months with the lowest environmental temperatures. The rate of obtaining and retaining heat also varied during the year and was highest during the reproductive season. Our results indicate that the variation of dorsal skin reflectance and thermal rates follows a complex pattern in lizard populations and is affected by both elevation and season.

The son-killer microbe Arsenophonus nasoniae is a widespread associate of the parasitic wasp Nasonia vitripennis in Europe.

Heritable microbes that exhibit reproductive parasitism are common in insects. One class of these are the male-killing bacteria, which are found in a broad range of insect hosts. Commonly, our knowledge of the incidence of these microbes is based on one or a few sampling sites, and the degree and causes of spatial variation are unclear. In this paper, we examine the incidence of the son-killer microbe Arsenophonus nasoniae across European populations of its wasp host, Nasonia vitripennis. In preliminary work, we noticed two female N. vitripennis producing highly female biased sex ratios in a field study from the Netherlands and Germany. When tested, the brood from Germany was revealed to be infected with A. nasoniae. We then completed a broad survey in 2012, in which fly pupal hosts of N. vitripennis were collected from vacated birds' nests from four European populations, N. vitripennis wasps allowed to emerge and then tested for A. nasoniae presence through PCR assay. We then developed a new screening methodology based on direct PCR assays of fly pupae and applied this to ethanol-preserved material collected from great tit (Parus major) nests in Portugal. These data show A. nasoniae is found widely in European N. vitripennis, being present in Germany, the UK, Finland, Switzerland and Portugal. Samples varied in the frequency with which they carry A. nasoniae, from being rare to being present in 50% of the pupae parasitised by N. vitripennis. Direct screening of ethanol-preserved fly pupae was an effective method for revealing both wasp and A. nasoniae infection, and will facilitate sample transport across national boundaries. Future research should examine the causes of variation in frequency, in particular testing the hypothesis that N. vitripennis superparasitism rates drive the variation in A. nasoniae frequency through providing opportunities for infectious transmission.

Elevation and blood traits in the mesquite lizard: Are patterns repeatable between mountains?

Ecogeographical patterns describe predictable variation in phenotypic traits between ecological communities. For example, high-altitude animals are expected to show elevated hematological values as an adaptation to the lower oxygen pressure. Mountains act like ecological islands and therefore are considered natural laboratories. However, the majority of ecophysiological studies on blood traits lack replication that would allow us to infer if the pattern reported is a local event or whether it is a widespread pattern resulting from larger-scale ecological processes. In lizards, in fact, the increase of hematological values at high altitudes has received mixed support. Here, for the first time, we compare blood traits in lizards along elevational gradients with replication. We tested the repeatability of blood traits in mesquite lizards between different elevations in three different mountains from the Trans-Mexican Volcanic Belt. We measured hematocrit, hemoglobin concentration, mean corpuscular hemoglobin concentration, and erythrocyte size in blood samples of low, medium, and high-elevation lizards. We obtained similar elevational patterns between mountains, but the blood traits differed among mountains. Middle-altitude populations had greater oxygen-carrying capacity than lizards from low and high altitudes. The differences found between mountain systems could be the result of phenotypic plasticity or genetic differentiation as a consequence of abiotic factors not considered.

Thermoregulatory behavior varies with altitude and season in the sceloporine mesquite lizard.

In ectothermic animals, body temperature is the most important factor affecting physiology and behavior. Reptiles depend on environmental temperature to regulate their body temperature, so geographic variation in environmental temperature can affect the biology of these organisms in the short and long term. We may expect physiological and behavioral responses to temperature change to be especially important in ectotherms inhabiting temperate zones, where different seasons present different thermal challenges. High-mountain temperate systems represent a natural laboratory for studies of evolutionary and plastic variation in thermal biology. The aim of the present study is to evaluate operative temperature with biophysical models, active body temperature under field conditions, preferred temperature in a thermal gradient in the laboratory, and thermal indexes in Sceloporus grammicus lizards along an elevational gradient. We measured these traits in three populations at 2500, 3400, and 4100 m elevation at different seasons of the year (spring, summer and autumn). Our results showed that operative temperature varied with season and elevation, with greater variation at middle and high elevations than at low elevations. Body temperature and preferred temperature varied with altitude and season but did not differ between sexes. Thermal quality was lowest in the high-altitude population and in the summer season. Thermoregulatory efficiency was highest in the three populations in the autumn. Our results suggest that thermoregulatory strategies vary with elevation and season, allowing individual lizards to confront annual fluctuations in the thermal environment and conflicting with some previous descriptions of Sceloporus lizards as thermally conservative.

Habitat-dependent Culicoides species composition and abundance in blue tit (Cyanistes caeruleus) nests.

Wild birds are hosts of Culicoides from as early on as the nesting stage when constrained to their nests. However, the environmental factors which determine the abundance and composition of Culicoides species within each bird nest are still understudied. We sampled Culicoides from Eurasian blue tit (Cyanistes caeruleus) nests found in 2 types of forests located in southern Spain. Firstly, we monitored the abundance of Culicoides species in bird nests from a dry Pyrenean oak deciduous forest and a humid mixed forest comprising Pyrenean and Holm oaks throughout 2 consecutive years. During the 3rd year, we performed a cross-fostering experiment between synchronous nests to differentiate the role of rearing environment conditions from that of the genetically determined or maternally transmitted cues released by nestlings from each forest. We found 147 female Culicoides from 5 different species in the birds' nests. The abundance of Culicoides was higher in the dry forest than in the humid forest. Culicoides abundance, species richness and prevalence were greater when the nestlings were hatched later in the season. The same pattern was observed in the cross-fostering experiment, but we did not find evidence that nestling's features determined by the forest of origin had any effect on the Culicoides collected. These results support the notion that habitat type has a strong influence on the Culicoides affecting birds in their nests, while some life history traits of birds, such as the timing of reproduction, also influence Culicoides abundance and species composition.

Oxidative status of blue tit nestlings varies with habitat and nestling size.

Oxidative status has been proposed as an important ecological and evolutionary force given that pro-oxidant metabolites damage molecules, cells and tissues, with fitness consequences for organisms. Consequently, organisms usually face a trade-off between regulating their oxidative status and other physiological traits. However, environmental stressors and the availability of dietary-derived antioxidants vary according to local conditions and, thus, organisms inhabiting different habitats face different oxidative pressures. Still, there is little information on how different environmental conditions influence the oxidative status of animals inhabiting terrestrial environments. In this work, we examined the variation in oxidative status in the blue tit (Cyanistes caeruleus), a bird species with hatching asynchrony. Specifically, we examined the oxidative status of the largest and the smallest nestlings in the brood, inhabiting four forests differing in food availability and ectoparasite prevalence. We measured lipid peroxidation (malondialdehyde; MDA) as a marker of oxidative damage, total antioxidant capacity (Trolox-equivalent antioxidant capacity; TEAC) and antioxidant enzymatic activity (catalase, glutathione S-transferase, glutathione peroxidase) in blood samples. The glutathione peroxidase (GPX) activity differed among the forests, being the highest in the pine forest and the lowest in a mixed oak (Quercus) forest in the most humid area. Lipid peroxidation was higher in larger nestlings, suggesting higher oxidative damage with an increasing growth rate. Neither brood size, laying date, nor ectoparasites were related to the oxidative status of nestlings. These results suggest that nest rearing conditions might shape the oxidative status of birds, having consequences for habitat-dependent variation in regulation of oxidative status.

Fast and dark: The case of Mezquite lizards at extreme altitude.

Sprint speed is a major performance trait in animal fitness involved in escaping from predators, obtaining food, and defending territory. Biotic and abiotic factors may influence sprint speed in lizards. Temperature decreases at higher altitude. Therefore, lizards at high elevations may require longer basking times to reach optimal body temperatures, increasing their vulnerability to predation and decreasing their time for other activities such as foraging or reproduction. Here, we tested whether the maximum sprint speed of a lizard that shows conservative thermal ecology varied along an altitudinal gradient comprising low (2500 m), middle (3400 m) and high-altitude (4300 m) populations. We also tested whether sprint speed was related to dorsal reflectance at different ecologically relevant temperatures. Given that the lizard Sceloporus grammicus shows conservative thermal ecology with altitude, we expected that overall average sprint speed would not vary with altitude. However, given that darker lizards heat up quicker, we expected that darker lizards would be faster than lighter lizards. Our results suggest that S. grammicus at high altitude are faster and darker at 30 °C, while lizards from low and middle altitude are faster and lighter in color at 20 °C than high altitude lizards. Also, our results suggest a positive relationship between sprint speed and dorsal skin reflectance at 10 and 20 °C. Sprint speed was also affected by snout-vent length, leg length, and leg thickness at 10 °C. These results suggest that, even though predation pressure is lower at extreme altitudes, other factors such as vegetation cover or foraging mode have influenced sprint speed.

Telomere length mirrors age structure along a 2200-m altitudinal gradient in a Mediterranean lizard.

The timing of organisms' senescence is developmentally programmed but also shaped by the interaction between environmental inputs and life-history traits. In ectotherms, ageing dynamics are still poorly understood even though their body temperature, metabolism, or growth trajectory are very sensitive to environmental changes. Here, we investigated the role of life-history traits such as age, sex, body size, body condition, and tail autotomy (i.e self-amputation) in shaping telomere length in six populations of the Algerian sand lizard (Psammodromus algirus) distributed along an elevational gradient from 300 to 2500 m above the sea level. Additionally, we compiled the available information on reptiles' telomere length in a review table. Our cross-sectional study shows that older lizards have longer telomeres, which might be mostly linked to the selective disappearance of individuals with shorter telomeres or, alternatively, mediated by a higher expression of telomerase across their life. In fact, variation in telomere length across elevation was explained by age structure of lizards; thus, in contrast to our predictions, altitude had no effect on telomere length in this study system. Telomere length was unaffected by tail regeneration and was sex-independent, but positively correlated with body condition, which might be linked to high somatic investment. Hence, our results suggest that life-history traits such as age or body condition can be major drivers of telomere dynamics for this species, whereas environmental conditions apparently had scarce or no effects on lizard telomeres. Our findings emphasize the relevance of understanding species' life histories for fully disentangling the causes and consequences of differences in ageing in ectotherms.

Variation in parasitoidism of Protocalliphora azurea (Diptera: Calliphoridae) by Nasonia vitripennis (Hymenoptera: Pteromalidae) in Spain.

Parasitoid wasps may act as hyperparasites and sometimes regulate the populations of their hosts by a top-down dynamic. Nasonia vitripennis (Walker, 1836) is a generalist gregarious parasitoid that parasitizes several host flies, including the blowfly Protocalliphora Hough, 1899 (Diptera, Calliphoridae), which in turn parasitizes bird nestlings. Nonetheless, the ecological factors underlying N. vitripennis prevalence and parasitoidism intensity on its hosts in natural populations are poorly understood. We have studied the prevalence of N. vitripennis in Protocalliphora azurea (Fallén, 1817) puparia parasitizing wild populations of pied flycatcher (Ficedula hypoleuca) and blue tit (Cyanistes caeruleus) birds in two Mediterranean areas in central and southern Spain. We found some evidence that the prevalence of N. vitripennis was higher in moist habitats in southern Spain. A host-dependent effect was found, since the greater the number of P. azurea puparia, the greater the probability and rate of parasitoidism by the wasp. Our results also suggest that N. vitripennis parasitizes more P. azurea puparia in blue tit nests than in pied flycatcher nests as a consequence of a higher load of these flies in the former. Based on the high prevalence of N. vitripennis in P. azurea puparia in nature, we propose that this wasp may regulate blowfly populations, with possible positive effects on the reproduction of both bird species.

Variations in chemical sexual signals of Psammodromus algirus lizards along an elevation gradient may reflect altitudinal variation in microclimatic conditions.

Chemical signals used in intraspecific communication are expected to evolve or to show phenotipic plasticity to maximize efficacy in the climatic conditions of a given environment. Elevational environmental gradients in mountains provide a good opportunity to test this hypothesis by examining variation in characteristics of signals in species found across different elevations with different climatic conditions. We analyzed by gas chromatography-mass spectrometry (GC-MS) the lipophilic fraction of the femoral gland secretions of male lizards Psammodromus algirus (Fam. Lacertidae) from six localities located along a 2200 m elevational gradient at Sierra Nevada Mountains (SE Spain). There was elevational clinal variation in climatic variables, number of femoral pores and in the relative proportions of some classes of compounds (i.e., ethyl esters of fatty acids, waxy esters, and aldehydes) but not others. We discuss how this variation would result in different physicochemical properties of the entire femoral secretion, which might help optimize the efficacy of chemical signals under the particular microclimatic conditions at each elevation.

Thermoregulation in the lizard Psammodromus algirus along a 2200-m elevational gradient in Sierra Nevada (Spain).

Achieving optimal body temperature maximizes animal fitness. Since ambient temperature may limit ectotherm thermal performance, it can be constrained in too cold or hot environments. In this sense, elevational gradients encompass contrasting thermal environments. In thermally pauperized elevations, ectotherms may either show adaptations or suboptimal body temperatures. Also, reproductive condition may affect thermal needs. Herein, we examined different thermal ecology and physiology capabilities of the lizard Psammodromus algirus along a 2200-m elevational gradient. We measured field (T(b)) and laboratory-preferred (T(pref)) body temperatures of lizards with different reproductive conditions, as well as ambient (T(a)) and copper-model operative temperature (T(e)), which we used to determine thermal quality of the habitat (d(e)), accuracy (d(b)), and effectiveness of thermoregulation (de-db) indexes. We detected no Tb trend in elevation, while T(a) constrained T(b) only at high elevations. Moreover, while Ta decreased more than 7 °C with elevation, T(pref) dropped only 0.6 °C, although significantly. Notably, low-elevation lizards faced excess temperature (T(e) > T(pref)). Notably, de was best at middle elevations, followed by high elevations, and poorest at low elevations. Nonetheless, regarding microhabitat, high-elevation de was more suitable in sun-exposed microhabitats, which may increase exposition to predators, and at midday, which may limit daily activity. As for gender, d(b) and d(e)-d(b) were better in females than in males. In conclusion, P. algirus seems capable to face a wide thermal range, which probably contributes to its extensive corology and makes it adaptable to climate changes.

Area-heterogeneity tradeoff and the diversity of ecological communities.

For more than 50 y ecologists have believed that spatial heterogeneity in habitat conditions promotes species richness by increasing opportunities for niche partitioning. However, a recent stochastic model combining the main elements of niche theory and island biogeography theory suggests that environmental heterogeneity has a general unimodal rather than a positive effect on species richness. This result was explained by an inherent tradeoff between environmental heterogeneity and the amount of suitable area available for individual species: for a given area, as heterogeneity increases, the amount of effective area available for individual species decreases, thereby reducing population sizes and increasing the likelihood of stochastic extinctions. Here we provide a comprehensive evaluation of this hypothesis. First we analyze an extensive database of breeding bird distribution in Catalonia and show that patterns of species richness, species abundance, and extinction rates are consistent with the predictions of the area-heterogeneity tradeoff and its proposed mechanisms. We then perform a metaanalysis of heterogeneity-diversity relationships in 54 published datasets and show that empirical data better fit the unimodal pattern predicted by the area-heterogeneity tradeoff than the positive pattern predicted by classic niche theory. Simulations in which species may have variable niche widths along a continuous environmental gradient are consistent with all empirical findings. The area-heterogeneity tradeoff brings a unique perspective to current theories of species diversity and has important implications for biodiversity conservation.

Ultraviolet radiation does not increase oxidative stress in the lizard Psammodromus algirus along an elevational gradient.

Lizards, as ectotherms, spend much time basking for thermoregulating exposed to solar radiation. Consequently, they are subjected to ultraviolet radiation (UVR), which is the most harmful component of solar radiation spectrum. UVR can provoke damages, from the molecular to tissue level, even cause death. Photooxidation triggered by UVR produces reactive oxidative species (ROS). When antioxidant machinery cannot combat the ROS concentration, oxidative stress occurs in the organisms. Given that UVR increases with elevation, we hypothesised that lizards from high elevations should be better adapted against UVR than lizards from lower elevations. In this work, we test this hypothesis in Psammodromus algirus along an elevation gradient (three elevational belts, from 300 to 2500 m above sea level). We ran an experiment in which lizards from each elevation belt were exposed to 5-hour doses of UVR (UV-light bulb, experimental group) or photosynthetically active radiation (white-light bulb, control group) and, 24 h after the exposure, we took tissue samples from the tail. We measured oxidative damage (lipid and protein peroxidation) and antioxidant capacity as oxidative-stress biomarkers. We found no differences in oxidative stress between treatments. However, consistent with a previous work, less oxidative damage appeared in lizards from the highlands. We conclude that UVR is not a stressor agent for P. algirus; however, our findings suggest that the lowland environment is more oxidative for lizards. Therefore, P. algirus is well adapted to inhabit a large elevation range, and this would favour the lizard in case it ascends in response to global climate change.

Thermal dependence of sprint performance in the lizard Psammodromus algirus along a 2200-meter elevational gradient: Cold-habitat lizards do not perform better at low temperatures.

Sprint speed has a capital relevance in most animals' fitness, mainly for fleeing from predators. Sprint performance is maximal within a certain range of body temperatures in ectotherms, whose thermal upkeep relies on exogenous thermal sources. Ectotherms can respond to diverse thermal environments either by shifting their thermal preferences or maintaining them through different adaptive mechanisms. Here, we tested whether maximum sprint speed of a lizard that shows conservative thermal ecology along a 2200-meter elevational gradient differs with body temperature in lizards from different elevations. Lizards ran faster at optimum than at suboptimum body temperature. Notably, high-elevation lizards were not faster than mid- and low-elevation lizards at suboptimum body temperature, despite their low-quality thermal environment. This result suggests that both preferred body temperature and thermal dependence of speed performance are co-adapted along the elevational gradient. High-elevation lizards display a number of thermoregulatory strategies that allow them to achieve high optimum body temperatures in a low thermal-quality habitat and thus maximize speed performance. As for reproductive condition, we did not find any effect of it on sprint speed, or any significant interaction with elevation or body temperature. However, strikingly, gravid females were significantly slower than males and non-gravid females at suboptimum temperature, but performed similarly well at optimal temperature.

Oxidative stress decreases with elevation in the lizard Psammodromus algirus.

Oxidative stress is considered one of the main ecological and evolutionary forces. Several environmental stressors vary geographically and thus organisms inhabiting different sites face different oxidant environments. Nevertheless, there is scarce information about how oxidative damage and antioxidant defences vary geographically in animals. Here we study how oxidative stress varies from lowlands (300-700 m asl) to highlands (2200-2500 m asl) in the lizard Psammodromus algirus. To accomplish this, antioxidant enzymatic activity (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase) and lipid peroxidation were assayed in tissue samples from the lizards' tail. Lipid peroxidation was higher in individuals from lowlands than from highlands, indicating higher oxidative stress in lowland lizards. These results suggest that environmental conditions are less oxidant at high elevations with respect to low ones. Therefore, our study shows that oxidative stress varies geographically, which should have important consequences for our understanding of geographic variation in physiology and life-history of organisms.

Phylogenetic evidence suggests the non-validity of the Iberian land snail genus Tartessiberus and confirms its synonymy with Iberus (Helicidae).

The monospecific genus Tartessiberus was described in the year 2021 including a single species (T.cilbanus). However, its description relied solely on morphological and anatomical data. In the present work, we use a fraction of the mitochondrial DNA cytochrome oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA) and the nuclear large ribosomal subunit (LSU) to clarify its validity through phylogenetic positioning. Knowledge of the distribution of this species is also improved by citing new locations and expanding the geographical range to approximately 200 km2. Additionally, a morphometric analysis of 259 shells is presented for comparisons with shells of the Iberusmarmoratus complex and testing the power of conchological features as a tool for specimen identification. The relatively high conchological variability found for T.cilbanus, together with the discovery of populations with intermediate conchological features between T.cilbanus and other closely related taxa, suggest that the determination of this species should be based on genetic criteria. Our molecular analyses demonstrate that T.cilbanus belongs to the Iberus genus, and thus, we proceed to update its taxonomic status to Iberuscilbanuscomb. nov., and, thus, to consider Tartessiberus from now on as a junior synonym of Iberus.

Environmental conditions influence host-parasite interactions and host fitness in a migratory passerine.

The study of host-parasite co-evolution is a central topic in evolutionary ecology. However, research is still fragmented and the extent to which parasites influence host life history is debated. One reason for this incomplete picture is the frequent omission of environmental conditions in studies analyzing host-parasite dynamics, which may influence the exposure to or effects of parasitism. To contribute to elucidating the largely unresolved question of how environmental conditions are related to the prevalence and intensity of infestation and their impact on hosts, we took advantage of 25 years of monitoring of a breeding population of pied flycatchers, Ficedula hypoleuca, in a Mediterranean area of central Spain. We investigated the influence of temperature and precipitation during the nestling stage at a local scale on the intensity of blowfly (Protocalliphora azurea) parasitism during the nestling stage. In addition, we explored the mediating effect of extrinsic and intrinsic factors and blowfly parasitism on breeding success (production of fledglings) and offspring quality (nestling mass on day 13). The prevalence and intensity of blowfly parasitism were associated with different intrinsic (host breeding date, brood size) and extrinsic (breeding habitat, mean temperature) factors. Specifically, higher average temperatures during the nestling phase were associated with lower intensities of parasitism, which may be explained by changes in blowflies' activity or larval developmental success. In contrast, no relationship was found between the prevalence of parasitism and any of the environmental variables evaluated. Hosts that experienced high parasitism intensities in their broods produced more fledglings as temperature increased, suggesting that physiological responses to severe parasitism during nestling development might be enhanced in warmer conditions. The weight of fledglings was, however, unrelated to the interactive effect of parasitism intensity and environmental conditions. Overall, our results highlight the temperature dependence of parasite-host interactions and the importance of considering multiple fitness indicators and climate-mediated effects to understand their complex implications for avian fitness and population dynamics.

How frequently do allegations of scientific misconduct occur in ecology and evolution, and what happens afterwards?

Scientific misconduct obstructs the advance of knowledge in science. Its impact in some disciplines is still poorly known, as is the frequency in which it is detected. Here, I examine how frequently editors of ecology and evolution journals detect scientist misconduct. On average, editors managed 0.114 allegations of misconduct per year. Editors considered 6 of 14 allegations (42.9%) to be true, but only in 2 cases were the authors declared guilty, the remaining being dropped for lack of proof. The annual rate of allegations that were probably warranted was 0.053, although the rate of demonstrated misconduct was 0.018, while the rate of false or erroneous allegations was 0.024. Considering that several cases of misconduct are probably not reported, these findings suggest that editors detect less than one-third of all fraudulent papers.