Risk for the introduction of exotic ticks and pathogens into Italy through the illegal importation of tortoises,Testudo graeca

In April 2008, 585 tortoises illegally imported into Italy from North Africa were examined for the presence of ticks. Of these, 221 tortoises (37.8%) were infested with a mean intensity of 3.9 ± 3.1 ticks (range 1–17 ticks). A total of 798 ticks (672 males, 125 females and one nymph) were collected and identified as Hyalomma aegyptium (L.) (Acari: Ixodidae). The overall male : female ratio observed was 5 : 1. The prevalence and mean intensity [±standard deviation (SD)] of ticks were higher among male (67.4%, 4.0 ± 3.2) than female (55.6%, 3.8 ± 3.1) tortoises, although this difference was not significant. By contrast, the prevalence and mean intensity of ticks were significantly higher on tortoises weighing >100 g (61.5%, 4.0 ± 3.2) compared with tortoises weighing <100 g (12.1%, 2.1 ± 1.1). Of the infested tortoises, 89.8% had ticks on their hind limbs, 21.0% on forelimbs, 18.6% on the tail and pre‐anal area, and 4.8% on the head; thus the hind limbs were evidently the preferred attachment site. The present report highlights the need to develop surveillance systems to prevent the introduction and spreading of exotic ticks and tick‐borne pathogens in Italy and other European countries.     

Some factors influencing the Moroccan distribution of the western Mediterranean spur-thighed tortoise, Testudo graeca graeca L., and those precluding its survival in NW Europe

The Moroccan distribution of Testudo graeca graeca L. is defined by locality records (109) and related to data from nearby or bioclimatically equivalent meteorological stations (86) to produce a rain-temperature climagram. Tortoises attain 1900 m in the High Atlas range. Tortoises occur where mean annual rainfall (P) is up to 1062 mm, and even 1112 mm where mean minimum monthly temperature for the coolest month (m) is below 0^oC and they are usually absent unless associated (90.0%) with Quercus ilex L. and Quercus suber L. woodland. Tortoises are absent from the Arctic-Alpine and Arid or Saharan bioclimates and where, without riverine habitat, Emberger's Quotient (Q) is below 19.5 (P = 139 mm) in the Steppe bioclimate. Below Q_= 39.1, they occur (88.9%) where there is Argania spinosa (L.) Maire woodland in the south-west and other broad-leaved and mixed wood- and scrubland species elsewhere. The Moroccan climagram includes and is extended by further stations (36) in the North African and southern European ranges generally ( T. g. graeca is reported in NW Egypt). The Moroccan range potentially occupies 167 000 m². Of a total of 45 stations below 550 m in NW Europe, the Western Mediterranean climagram only overlaps 12 in more oceanic Britain and Ireland; 11 are coastal or insular and 11 where Quercus woodland extends the natural range with m below 0^oC in montane areas. Tortoises do not occur where mean annual sunshine much exceeds 3250 h in northern Africa or below c. 2400 h in NW Europe. Tortoises introduced from the Mediterranean region by the pet trade are unable to reproduce if they survive in NW Europe for insolation is insufficient for egg incubation and hatchling survival.     

Assessing changes in habitat quality due to land use changes in the spur-thighed tortoise Testudo graeca using hierarchical predictive habitat models

In this study we propose a model-building approach based on the hierarchical integration of the main environmental factors (climate, topography/lithology, and land uses) determining the distribution of the spur-thighed tortoise in south-east Spain. Data on the presence/absence of the species were primarily based on information derived from interviews to shepherds. The hierarchical modelling exercise consisted of three steps. First, we constructed a model for the entire region using climate variables, thus obtaining a potential climatical model. Second, we introduced variables referring to topography and lithology that fall within the climatic distribution range ( potential model). Third, by using this second model as a starting point, we included land use variables to obtain the actual distribution model.
We analysed the changes in the values of probability of the presence of this species for a given cell between the potential and the actual model, assessing areas where habitat quality has decreased, been maintained or increased. The spatial representation of these changes was highly coherent. A discriminant analysis linked areas where habitat quality has dropped with agriculture landscapes, whereas those areas where habitat quality has been maintained or increased were located mainly in shrublands. Twenty-five per cent (479 km²) of the potential distribution of the species became suboptimal when land use was included, which emphasizes the importance of land use changes in both the range dynamics and the conservation of the spur-thighed tortoise in south-east Spain.     

Ultrastructure of the respiratory epithelium in the lungs of the tortoise,Testudo graeca

The respiratory epithelium in the lungs of the tortoise (Testudo graeca) has been studied by electron microscopy. The epithelium consists of a mosaic of two different cell types (here called "pneumonocytes"). Type I pneumonocytes are roughly squamous and possess attenuated flanges of cytoplasm which extend over the septal capillaries. Localized cytoplasmic expansions are often present near the periphery of these flanges. Most of the organelles are concentrated in the perinuclear region; the most prominent of these are the mitochondria and osmiophilic inclusions. In contrast, type II pneumonocytes are cuboidal and are richly endowed with organelles including large Golgi complexes, extensive endoplasmic reticulum and numerous inclusion bodies. The morphological evidence suggests that type I pneumonocytes are involved in the secretion of osmiophilic material (presumed to be pulmonary surfactant) and in maintaining the integrity of the air-blood barrier. Type II pneumonocytes appear to be concerned solely with the production of surfactant.     

Hyalomma aegyptium as dominant tick in tortoises of the genus Testudo in Balkan countries, with notes on its host preferences

Collection of 1327 ticks sampled throughout Greece, Bulgaria, Romania and Croatia, from 211 tortoises belonging to three species, Testudo marginata Schoepff, T. graeca Linnaeus, and T. hermanni Gmelin, revealed the presence of four species of ixodid ticks, namely Hyalomma aegyptium (Linnaeus), Haemaphysalis sulcata Canestrini and Fanzago, H. inermis Birula and Rhipicephalus sanguineus (Latreille). Study confirmed the strong dominance of all life stages of H. aegyptium among ticks parasitizing west Palaearctic tortoises of genus Testudo Linnaeus. Furthermore, a considerable portion of ticks collected from tortoises in southwestern Bulgaria represent larvae and nymphs of H. sulcata. At the same area we collected as exception one larva and one nymph of H. inermis from a single specimen of T. hermanni. Our findings of four adults of R. sanguineus is the first record of this species from reptilian host. According to our results achieved on localities with syntopic occurrence of two tortoise species, T. marginata and T. graeca represent in the Balkans the principal hosts of H. aegyptium, whereas T. hermanni serves only as an alternative host in the areas close to range of either T. marginata or T. graeca.     

Attachment sites of the tick Amblyomma marmoreum on its tortoise host,Geochelone pardalis

Leopard tortoises (n=162) were collected over a period of 19 months at the National Zoological gardens, Pretoria, South Africa and the attachment sites of larvae, nymphs and adults of A. marmoreum monitored. Most of the larvae (80%) and nymphs (87%) were found on the anterior parts of the tortoise while adults (90%) were found mainly on the posterior regions of the host body. The immature stages were predominant in soft skinned areas protected by the carapace especially the neck and upper leg areas. Male and female ticks were most commonly found on the posterior armpit. posterior legs and the areas surrounding the base of the tail. Interstadial competition as a major factor influencing attachment site segregation is doubtful. Anterior attachment site selection of the immature stages is believed to result largely from ticks lying passively in wait and then climbing onto the host as it moves through the vegetation and the requirement for soft skinned and protected areas to allow for blood feeding. Adult females usually attach posteriorly in areas that allow them to fully engorge without being dislodged by mechanical disturbance, while males prefer to attach at sites where they are protected but still remain in close proximity to female pheromone signals.     

Spatial heterogeneity in the effects of climate change on the population dynamics of a Mediterranean tortoise

Climatic shifts may increase the extinction risk of populations, especially when they are already suffering from other anthropogenic impacts. Our ability to predict the consequences of climate change on endangered species is limited by our scarce knowledge of the effects of climate variability on the population dynamics of most organisms and by the uncertainty of climate projections, which depend strongly on the region of the earth being considered. In this study, we analysed a long‐term monitoring programme (1988–2009) of Hermann's tortoise (Testudo hermanni) aimed at evaluating the consequences of the drastic changes in temperature and precipitation patterns predicted for the Mediterranean region on the demography of a long‐lived species with low dispersal capability and already suffering a large number of threats. Capture–recapture modelling of a population in the Ebro Delta (NE Spain) allowed us to assess the effect of climate variability on the survival of tortoises. Winter rainfall was found to be the major driver of juvenile and immature survival, whereas that of adults remained high and constant across the study. Furthermore, local climate series obtained ad hoc from regional climate simulations, for this and 10 additional Mediterranean locations where tortoises occurred, provided us with reliable future climate forecasts, which were used to simulate the fate of these populations under three precipitation scenarios (mean, wet and dry) using stochastic population modelling. We show that a shift to a more arid climate would have negative consequences for population persistence, enhancing juvenile mortality and increasing quasiextinction risk because of a decrease in recruitment. These processes varied depending on the population and the climate scenario we considered, but our results suggest that unless other human‐induced causes of mortality are suppressed (e.g. poaching, fire, habitat fragmentation), climate variability will increase extinction risk within most of the species’ current range.     

The impact of agro‐pastoral abandonment on the Rock Partridge Alectoris graeca in the Apennines

Human depopulation of rural mountain areas and the consequent abandonment of traditional land management are among the greatest driving forces behind changes in mountain ecosystems in Western Europe. Tree and shrub encroachment lead to an increase in landscape matrix uniformity and habitat fragmentation. For some animal species, this represents an unusual case of habitat loss caused by secondary succession. The animal species associated with this agro‐pastoral habitat may suffer from decreased connectivity as a consequence. The Rock Partridge Alectoris graeca is a species endemic to European mountains that represents a model for investigating the impact of habitat loss. We compared the habitat suitability of the Apennine Rock Partridge prior to abandonment of traditional agro‐pastoral activities by aerial photography with the current landscape, in order to investigate the effect of secondary succession on the distribution and viability of the species. We assessed the historical distribution (c. 1900–1950) by quantifying anecdotal evidence from interviews, and the current distribution (2005) from survey data. We applied ecological niche factor analysis and connectivity approaches to evaluate change in habitat suitability over this time scale. Moreover, to quantify landscape connectivity, we evaluated the relative importance of each patch in the two periods. Results indicated that to maintain a viable population in the Apennines, the species requires an ensemble of ecological conditions considerably different from the current situation. We observed a drastic decrease in connectivity as a result of a reduction in numbers and size of high suitability patches. This is most probably the primary cause of the current decline of the Rock Partridge population in the Apennines.     

The limits of demographic buffering in coping with environmental variation

Animal populations have developed multiple strategies to deal with environmental change. Among them, the demographic buffering strategy consists in constraining the temporal variation of the vital rate(s) that most affect(s) the overall performance of the population. Tortoises are known to buffer their temporal variation in adult survival, which typically has the highest contribution to the population growth rate λ, at the expense of a high variability on reproductive rates, which contribute far less to λ. To identify the effects of projected increases in droughts in its natural habitat, we use field data collected across 15 locations of Testudo graeca in southeast Spain over a decade. We analyse the effects of environmental variables on reproduction rates. In addition, we couple the demographic and environmental data to parameterise an integral projection model to simulate the effects of different scenarios of drought recurrence on λ under different degrees of intensity in the survival–reproduction tradeoff. We find that droughts negatively affect the probability of laying eggs; however, the overall effects on λ under the current drought recurrence (one/decade) are negligible when survival is constant (independent of the reduction of reproduction by drought events) and when survival increased as a tradeoff with the reduction of reproduction rates, with a threshold to population viability at three or more droughts/decade. Additionally, we show that, although some species may buffer current environmental regimes by carefully orchestrating how their vital rates vary through time, a demographic buffering strategy is insufficient to ensure population viability in extreme regimes. Our findings support the hypothesis that the demographic buffering strategy has a limit of effectiveness when adverse conditions occur frequently. Our methodological approach provides a framework for ecologists to determine how effective the management of environmental drivers can be for demographically buffering populations, and which scenarios may not provide long-term population persistence.     

The effect of various host species on the feeding performance of immature stages of the tick Hyalomma truncatum (Acari: Ixodidae)

In order to determine the effect of various hosts on the feeding performance of the tick Hyalomma truncatum, we used three mammalian species as hosts. Larvae and nymphs of H. truncatum were fed, under controlled laboratory conditions, on gerbils, guinea-pigs and rabbits. The larvae fed for 4.3±1.4 days on gerbils, 5.6±1.3 days on guinea-pigs and 4.7±1.2 days on rabbits. The mean weights of the larvae which fed on the rabbits, guinea-pigs and gerbils were 0.58± 0.09, 0.46±0.04 and 0.45±0.04 mg. respectively. The feeding periods of the nymphs on gerbils, guinea-pigs and rabbits were 7.9±1.3, 8.6±1.3 and 9.6±2.2 days respectively. The mean weights of the nymphs which fed on the gerbils, guinea-pigs and rabbits were 22.5±2.8, 19.7±1.3 and 15.8±1.4 mg, respectively. Hyalomma truncatum demonstrated a life cycle of a three-host tick on gerbils and guinea-pigs and of a two-host tick on rabbits. The evolutionary advantage of a two-host cycle over a three-host cycle in metastriate ticks is discussed.     

Observations on changes in abundance of questing Ixodes ricinus,castor bean tick,over a 35‐year period in the eastern part of its range (Russia,Tula region)

Ixodes ricinus (Acari: Ixodidae) L. transmit a wide variety of pathogens to vertebrates including viruses, bacteria and protozoa. Understanding of the epidemiology of tick‐borne infections requires basic knowledge of the regional and local factors influencing tick population dynamics. The present study describes the results of monitoring of a questing I. ricinus population, conducted over 35 years (1977–2011) in the eastern, poorly studied part of its range (Russia, Tula region). We have found that the multiannual average abundance of ticks is small and varies depending on the biotope and degree of urban transformation. Tick abundance for the first 14 years of observations (1977–1990) was at the lower limit of the sensitivity of our methods throughout the study area (0.1–0.9 specimens per 1‐km transect). In the following 21 years (1991–2011), a manifold increase in abundance was observed, which reached 18.1 ± 1.8 individuals per 1‐km transect in moist floodplain terraces, and 4.8 ± 0.9 in xerophylic hill woods. Long‐term growth of tick abundance occurred in spite of a relatively constant abundance of small mammals and only minor fluctuations in the abundance of large wild animals. Climate and anthropogenic changes appear to be the main contributors to increased abundance of the tick.     

The role of environment in shaping the genetic diversity of the subalpine mosquito,Aedes rusticus (Diptera,Culicidae)

The relative involvement of larval dietary tolerance to the leaf-litter toxic polyphenols in shaping population genetic structure of the subalpine mosquito Aedes rusticus was examined. This was compared with other parameters such as geographical range, type of vegetation surrounding the breeding site, and occurrence of annual larvicidal treatments. Population genetic structure was analysed at 10 presumed neutral polymorphic isoenzyme loci. Toxicological comparisons involved standard bioassays performed on larvae fed on toxic decomposed leaf litter. Significant overall genetic differentiation was observed among the 22 studied populations and within the five defined geographical groups. Analysis of molecular variance revealed an absence of relation between genetic and environmental parameters, genetic variance being essentially found within populations. This suggested that the larval dietary tolerance to the toxic leaf litter and the other studied parameters poorly influence population genetic structure. The local adaptation of subalpine mosquito populations to the surrounding vegetation thus appears as a labile trait. Such a dynamic adaptation is also suggested by the correlation between geographical and toxicological distances and the correlation between dietary tolerance to the leaf-litter toxic polyphenols and annual larvicidal treatments.     

The role of climate in limiting European resident bird populations

Abstract Aim To study densities of eight groups of resident forest bird populations across Europe to examine their association with abiotic (temperature, precipitation) factors. Location Europe. Methods Densities of residents (and migrant birds, which were used as a control group) were extracted from published breeding bird censuses. For each census location we obtained geographical co‐ordinates (latitude and longitude), temperature and precipitation variables describing both breeding and non‐breeding seasons. Resident densities were first examined separately in relation to co‐ordinates and principal component axes, which were extracted from temperature and precipitation variables. The relative impact of each explaining factor (co‐ordinates and principal component axis) on resident densities was checked by using residual examination and partial correlation. Results Densities of resident birds were in general negatively correlated with both latitude and longitude and temperature and precipitation factors, but latitude and temperature proved to be the strongest individual factors along which resident densities varied. The higher the latitude or the lower the temperatures, the lower were the densities of most resident birds. Partial correlation analysis suggested that of those two factors, latitude was the dominant one. Both the density of resident and migrant birds decreased towards the north, but the decrease of residents was steeper, and in the north they comprised only a small fraction of breeding bird numbers, whereas further south they commonly comprise half of the breeding bird numbers. Main conclusions The best explanatory factor for resident densities was latitude. For this reason, it was difficult to separate the relative effect of each individual factor, because latitude partly describes all the original variables (temperature and precipitation). The results suggested that precipitation was of less importance and that the interplay between latitude and ambient temperatures was not the sole factor behind the strong effect of latitude. We suggest that the coupled effect of harshening climate and decreasing amount of available energy with increasing latitude is limiting the population sizes of resident birds. We also propose that the effect of those factors is most apparent in northern Fennoscandia, where resident densities are suggested to be lower than would be expected on the basis of summer time carrying capacity.     

Local adaptation and population structure at a micro-geographical scale of a fungal parasite on its host plant

Local adaptation, which has been detected for several wild pathosystems is influenced by gene flow and recombination. In this study, we investigate local adaptation and population structure at a fine scale in wild populations of a plant-pathogen fungus. We sampled hierarchically strains of Colletotrichum lindemuthianum in a wild population of its host. The analysis of AFLP patterns obtained for 86 strains indicated that: (i) many different haplotypes can be discriminated, although occurrence of recombination could not be shown; (ii) migration between adjacent plants seemed rare during the season; and (iii) neutral diversity is structured according to groups of plants and individual host plants. Furthermore, we tested for the occurrence of local adaptation using a cross-inoculation experiment. Our results showed local adaptation at the scale of the individual host plant. These results indicate that fine-scale dynamics has evolutionary consequences in this pathosystem.     

Spatial population genetic structure of a bacterial parasite in close coevolution with its host

Knowledge of a species’ population genetic structure can provide insight into fundamental ecological and evolutionary processes including gene flow, genetic drift and adaptive evolution. Such inference is of particular importance for parasites, as an understanding of their population structure can illuminate epidemiological and coevolutionary dynamics. Here, we describe the population genetic structure of the bacterium Pasteuria ramosa, a parasite that infects planktonic crustaceans of the genus Daphnia. This system has become a model for investigations of host–parasite interactions and represents an example of coevolution via negative frequency‐dependent selection (aka “Red Queen” dynamics). To sample P. ramosa, we experimentally infected a panel of Daphnia hosts with natural spore banks from the sediments of 25 ponds throughout much of the species range in Europe and western Asia. Using 12 polymorphic variable number tandem repeat loci (VNTR loci), we identified substantial genetic diversity, both within and among localities, that was structured geographically among ponds. Genetic diversity was also structured among host genotypes within ponds, although this pattern varied by locality, with P. ramosa at some localities partitioned into distinct host‐specific lineages, and other localities where recombination had shuffled genetic variation among different infection phenotypes. Across the sample range, there was a pattern of isolation by distance, and principal components analysis coupled with Procrustes rotation identified congruence between patterns of genetic variation and geography. Our findings support the hypothesis that Pasteuria is an endemic parasite coevolving closely with its host. These results provide important context for previous studies of this model system and inform hypotheses for future research.     

气候变化对大兴安岭北部蒙古栎种群动态的影响

通过对气象因子和样地数据分析表明,20余年来大兴安岭北部气候趋于变暖,低海拔地带蒙古栎呈现明显的进展趋势,演替趋于以蒙古栎为优势种的阔叶林,海拔较高地带蒙古栎更新不良,演替趋于兴安落叶松和几种阔叶树的混生林,蒙古栎种群发展与干暖化具有一致性,在各类气象因子中,5月均低温是影响蒙古栎更新的决定性因子,由海拔升高引起的区域干燥度降低也是影响更新的重要因子,这也说明蒙古栎对冷湿生境的不适应性。     

The genetic structure of hawthorn-infesting Rhagoletis pomonella populations in Mexico: implications for sympatric host race formation

The genetic origins of species may not all trace to the same time and place as the proximate cause(s) for population divergence. Moreover, inherent gene-flow barriers separating populations may not all have evolved under the same geographical circumstances. These considerations have lead to a greater appreciation of the plurality of speciation: that one geographical mode for divergence may not always be sufficient to describe a speciation event. The apple maggot fly, Rhagoletis pomonella , a model system for sympatric speciation via host-plant shifting, has been a surprising contributor to the concept of speciation mode plurality. Previous studies have suggested that past introgression of inversion polymorphism from a hawthorn-fly population in the trans-Mexican volcanic belt (EVTM) introduced diapause life-history variation into a more northern fly population that subsequently contributed to sympatric host race formation and speciation in the United States (US). Here, we report results from a microsatellite survey implying (i) that volcanic activity in the eastern EVTM may have been responsible for the initial geographical isolation of the Mexican and northern hawthorn-fly populations c . 1.57 mya; and (ii) that flies in the Sierra Madre Oriental Mountains (SMO) likely served as a conduit for past gene flow from the EVTM into the US. Indeed, the microsatellite data suggest that the current US population may represent a range expansion from the northern SMO. We discuss the implications of these findings for sympatric race formation in Rhagoletis and speciation theory.