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Multiple mating is common among ticks, a large group of haematophagous ectoparasites, but multiple paternity has rarely been investigated. Multiple paternity may be common because the resultant increased genetic diversity allows ticks to rapidly evolve in relation to host responses and increases colonisation potential in novel habitats. Knowledge concerning mating systems is important because ticks may have profound effects on their hosts and are the principal transmitters of many pathogenic agents. In the current study, we investigated the mating system of the nidicolous tick Ixodes arboricola . These ticks attach to their bird hosts in the nest, which restricts gene flow but facilitates finding a partner off-host. Having genetically variable offspring may be beneficial for ticks which may encounter very different conditions when dispersed to the nest of another host type. We conducted an experiment in which female ticks fed on great tit nestlings and mated with two males in three treatments of the females: mating with both males before feeding, mating with one male before and the other male after feeding, or mating with both males after feeding. We investigated paternity with microsatellites. In a complementary experiment we investigated male preference for unfed or engorged females, and measured mating duration. We predicted (i) there would be multiple mating by I. arboricola males and females, leading to multiple paternity, and (ii) males would prefer to mate with engorged females and those matings would last longer because engorged females present a higher probability of successful reproduction. We found multiple paternity within clutches but no indications of sperm precedence. Males preferred to mate with engorged females and those matings lasted significantly longer, even including attachment beyond egg deposition. We suggest such mate guarding and male preference for mating after feeding is adaptive because there is no first male precedence. Male preference for mating after feeding may also be adaptive because dispersal is low and females are available after the blood meal. [ABSTRACT FROM AUTHOR]

Similar to many other parasites, the distribution of ticks among hosts is strongly skewed, with few hosts harbouring the majority of parasites. Because parasite-induced impairment of host health, parasite population growth and pathogen transmission are density-dependent, understanding why tick distributions are skewed is important for the population and evolutionary dynamics of both parasite and host. However, there is currently no knowledge concerning parasites that strongly depend on individual hosts. Here, we investigated the effects of tick density on feeding performance in the nidicolous tree-hole tick, Ixodes arboricola , which feeds on cavity-nesting birds and is the carrier of several tick-borne pathogens. Nidicolous ticks reside in or close to their hosts’ nests and therefore depend strongly on individual hosts and their offspring. Increased feeding success at higher densities (facilitation) may therefore be detrimental to the ticks themselves. We investigated the effects of tick density on feeding performance of I. arboricola by infesting great tit nestlings with one to five adult ticks, which is within the natural range. There was no effect of tick density on initial attachment success, attachment after 48 h or engorgement weight, but tick recovery rates increased significantly with tick density. We also found a modest increase in nestling body mass with tick density, suggesting that birds over-compensate resource drainage by the ticks and, by doing this, anticipate the costs of a tick-rich environment. Our results indicate that nidicolous ticks perform better when feeding in aggregation. This may have important consequences for population dynamics and consequently pathogen transmission. [ABSTRACT FROM AUTHOR]

1. Little information is available on the ecological interactions between ticks and their hosts under natural conditions, and particularly so for avian hosts. To understand this host–parasite interaction it is necessary to assess the physiological harm ticks can do to their host. 2. We combined observational and experimental (field and laboratory) data to examine the effects of a common tick species with major economic importance, the sheep tick ( Ixodes ricinus), on the health status of a common passerine bird, the great tit ( Parus major). 3. In the laboratory experiment a parallel group design was carried out in which the birds of the experimental group were infested with 3–10 nymphs, whereas the birds of the control group were kept free of ticks and received a sham treatment. Both groups were stratified according to age and sex. Health parameters were measured the day before and 3 days after infestation or sham treatment: haematocrit level, erythrocyte sedimentation rate, leucocyte concentration and general body condition (body mass corrected for body size). 4. No effects of age were observed on any of the health parameters. The decrease in haematocrit level in the experimental group was significantly greater than in the control group. Moreover, infested males suffered more blood depletion than infested females. The increase in sedimentation rate was greater in the experimental group than in the control group. Surprisingly, no treatment effects were found on leucocyte concentrations, which may indicate immunoregulation by the ticks on components of the birds’ cellular immune response. Also no difference in general body condition between the treatment groups was found. None of the infested birds died during infestation. 5. Lower haematocrit levels in infested birds, but unaffected leucocyte concentrations and general body condition are confirmed by field data (experimental and observational) of adult birds during breeding season. 6. Neither haematocrit level nor general body condition was associated with parasite intensity among infested birds, suggesting that immature Ixodes ricinus are not resource limited at high natural densities. Still, the measurable direct harm caused by sheep tick infestations calls for further study on its importance for the evolutionary ecology of passerine hosts. [ABSTRACT FROM AUTHOR]

Eight nests of the Giant Conebill (Oreomanes fraseri, Family Thraupidae) were found in Polylepis forest fragments in Cochabamba Department (Sacha Loma and Cuturi) of Bolivia during 2002-2004. The breeding period of the Giant Conebill extended from September to December at the beginning of the rainy season. The nests were open cups with an average outside width of 20 cm and a thick rim of 5.5 cm; the average clutch size was 1.86. Nests were constructed mostly with parts of Polylepis trees and a variety of mosses. All nests located were in the interior of forests, well camouflaged, and in trees with an average height of 3.16 m. Control of human disturbance, especially burning, is needed for protection of the habitat of the Giant Conebill. [ABSTRACT FROM AUTHOR]

Although relatedness between mates is of considerable evolutionary and ecological significance, the way in which the level of relatedness is determined by different behavioural processes remains largely unknown. We investigated the role of behaviour in predicting mate relatedness in great tits using genotypic markers and detailed observations. We studied how mate relatedness is influenced by natal dispersal, inbreeding/outbreeding avoidance after natal dispersal and a behaviour not previously considered that influences membership to social aggregations, namely family escorting behaviour by parents. Among locally born individuals, the level of mate relatedness decreased with natal dispersal distance for females, but not for males. In contrast, mate relatedness was negatively related to the extent of family movements for males, but not for females. However, family movements did not predict dispersal distance for either sex. Local recruits were more related to their mates than immigrants, but this was only significant for females. No evidence was found for inbreeding/outbreeding avoidance after dispersal. Our results suggest that, in highly mobile species, mating options are spatially and/or socially limited, and that parents influence mating options of their offspring before dispersal. [ABSTRACT FROM AUTHOR]

Fireflies are the classic example of organisms that use light signalling for sexual communication. However, many genera have diurnally active adults for which the use of light signals for courtship seems unlikely. It is generally accepted that diurnal fireflies use pheromones instead of light signalling for sexual communication, even though robust observational data or convincing experimental evidence is lacking. In several field experiments, we investigated whether sexual communication in the diurnal P. hemipterus is based upon pheromones rather than on light emission. During the daytime, males were attracted to females without the aid of visual cues. Males coming from the downwind side of females arrived first. Arrival directions of males to females were strongly nonrandom and were correlated with downwind direction, i.e. possibly into the direction from which a pheromone plume is dispersed. Males arrived more rapidly when the wind came from a fixed direction and wind speed was high. Although the presumed pheromone signal still attracted males at a distance of 20m, its maximal sampling range was at a relatively close range (ca. 43m after 3h). More males were attracted when females showed signalling behaviour. These results strongly suggest that sexual communication in P. hemipterus is based entirely on pheromones. [Copyright &y& Elsevier]

We studied dispersal movements by sibling pairs of great tits,Parus major, and blue tits,P. caeruleus, in a patchy environment, in order to test whether siblings are more similar in dispersal than expected by chance. Because of possible common environmental effects due to the heterogeneity and finiteness of the study area, we compared the similarity among siblings with the similarity between each sibling and an unrelated bird that fledged in the same patch and year, as close to the siblings’ nest as possible. Siblings of both species were not more similar in dispersal distance than they were to control birds. However, great tit siblings dispersed in similar directions compared to control birds, and this result was not affected by the degree of matching between sibling and control birds. As a consequence, siblings ended up breeding at closer distances from one another than control birds. Heritability values calculated from parent-offspring regressions were close to zero, suggesting that there is no additive genetic variance for dispersal distance or dispersal direction. We propose that similarity in dispersal direction originates from association of siblings during dispersal or during activities that influence the choice of direction, such as postfledging family movements. Our results show that non-independence in the choice of dispersal direction by siblings may influence small-scale kin structure in this population with high local recruitment. [ABSTRACT FROM AUTHOR]

Journal of Animal Ecology (2004) 73, 261–271 [ABSTRACT FROM AUTHOR]

Abstract Studies of inbreeding depression or kin selection require knowledge of relatedness between individuals. If pedigree information is lacking, one has to rely on genotypic information to infer relatedness. In this study we investigated the performance (absolute and relative) of 10 marker-based relatedness estimators using allele frequencies at microsatellite loci obtained from natural populations of two bird species and one mammal species. Using Monte Carlo simulations we show that many factors affect the performance of estimators and that different sets of loci promote the use of different estimators: in general, there is no single best-performing estimator. The use of locus-specific weights turns out to greatly improve the performance of estimators when marker loci are used that differ strongly in allele frequency distribution. Microsatellite-based estimates are expected to explain between 25 and 79% of variation in true relatedness depending on the microsatellite dataset and on the population composition (i.e. the frequency distribution of relationship in the population). We recommend performing Monte Carlo simulations to decide which estimator to use in studies of pairwise relatedness. [ABSTRACT FROM AUTHOR]

We studied the winter foraging niches of tits and related species indeciduous forest fragments varying in size between 1and 30 ha (plus one forest of 200 ha) in order to investigate the influence of forestfragmentation on foraging niches. Very few correlations between niche structure (foraging niche, width and forest size or isolation turned out to be significant. This implies that either the species that disappear in small fragments are those that suffer most from competition (making the effect unmeasurable), or that competition is relatively unimportant for the niche structure. In any case we find no evidence that foraging niches are strongly affected by the changes (in habitat and/or community structure) associated with fragmentation. [ABSTRACT FROM AUTHOR]

Abstract Green spaces in the city are important for human wellbeing, but are also zones in which humans can become infected with zoonotic diseases. Therefore, there is a need to understand how infection risk is related to green space characteristics, wildlife communities and connectivity with rural areas hosting reservoir populations of hosts. Our hypothesis is that wildlife hosts in urban green spaces, and thereby the prevalence of questing ticks and their Lyme disease causing pathogens (Borrelia burgdorferi s.l.), can be partly predicted based on green space characteristics as well as measures of connectivity to known source areas. We sampled ticks in twenty-two green spaces during Spring (2014 and 2016) and Autumn 2016, located along an urbanization gradient in Antwerp (Belgium). More than 18,000 m2 was sampled, with tick densities ranging from 0 to 386 individuals/100 m2. We estimated connectivity using the least-cost algorithm as either the cost distance to the nearest green space, or to a known population of roe deer (Capreolus capreolus), known to be an important tick propagation host. Both connectivity measures turned out to be correlated, reflecting a gradient in green space isolation from the periphery to the urban center. In 87% of plots where ticks were trapped, at least one Borrelia -infected tick was found. The overall Borrelia -prevalence in nymphs was 17.8%, in adults 32.6%. Density of infected ticks decreased with urbanization and increased with connectivity. Nymphs in larger green spaces were more likely to be infected. While density and infection prevalence for adults increased with the amount of neighboring agricultural land, the larval density and nymphal infection prevalence decreased. Interestingly, the proportion of Borrelia genospecies associated with birds or mammals was comparable in rural and (sub)urban areas (bird/mammal: 0.38), suggesting that even in small green spaces Borrelia infections can persist in local host populations. Graphical abstract Unlabelled Image Highlights • Landscape effects on pathogen flows are poorly understood in urban areas. • Green space characteristics based on Graph Theory principles were quantified. • Collected ticks over an urbanization gradient were screened for Lyme disease. • Connectivity and plot size affected tick density and disease prevalence. • Tick-borne infections should be taken into account when designing green spaces. [ABSTRACT FROM AUTHOR]

Conservation actions often focus on restoration or creation of natural areas designed to facilitate the movements of organisms among populations. To be efficient, these actions need to be based on reliable estimates or predictions of landscape connectivity. While circuit theory and least-cost paths (LCPs) are increasingly being used to estimate connectivity, these methods also have proven limitations. We compared their performance in predicting genetic connectivity with that of an alternative approach based on a simple, individual-based ''stochastic movement simulator'' (SMS). SMS predicts dispersal of organisms using the same landscape representation as LCPs and circuit theory-based estimates (i.e., a cost surface), while relaxing key LCP assumptions, namely individual omniscience of the landscape (by incorporating perceptual range) and the optimality of individual movements (by including stochasticity in simulated movements). The performance of the three estimators was assessed by the degree to which they correlated with genetic estimates of connectivity in two species with contrasting movement abilities (Cabanis's Greenbul, an Afrotropical forest bird species, and natterjack toad, an amphibian restricted to European sandy and heathland areas). For both species, the correlation between dispersal model and genetic data was substantially higher when SMS was used. Importantly, the results also demonstrate that the improvement gained by using SMS is robust both to variation in spatial resolution of the landscape and to uncertainty in the perceptual range model parameter. Integration of this individual-based approach with other developing methods in the field of connectivity research, such as graph theory, can yield rapid progress towards more robust connectivity indices and more effective recommendations for land management. [ABSTRACT FROM AUTHOR]

The impact of demographic parameters on the genetic population structure and viability of organisms is a long-standing issue in the study of fragmented populations. Demographic and genetic tools are now readily available to estimate census and effective population sizes and migration and gene flow rates with increasing precision. Here we analysed the demography and genetic population structure over a recent 15- year time span in five remnant populations of Cabanis's greenbul (Phyllastrephus cabanisi), a cooperative breeding bird in a severely fragmented cloud forest habitat. Contrary to our expectation, genetic admixture and effective population sizes slightly increased, rather than decreased between our two sampling periods. In spite of small effective population sizes in tiny forest remnants, none of the populations showed evidence of a recent population bottleneck. Approximate Bayesian modelling, however, suggested that differentiation of the populations coincided at least partially with an episode of habitat fragmentation. The ratio of meta-Ne to meta-Nc was relatively low for birds, which is expected for cooperative breeding species, while Ne/Nc ratios strongly varied among local populations. While the overall trend of increasing population sizes and genetic admixture may suggest that Cabanis's greenbuls increasingly cope with fragmentation, the time period over which these trends were documented is rather short relative to the average longevity of tropical species. Furthermore, the critically low Nc in the small forest remnants keep the species prone to demographic and environmental stochasticity, and it remains open if, and to what extent, its cooperative breeding behaviour helps to buffer such effects. [ABSTRACT FROM AUTHOR]

The endophilic tick Ixodes arboricola infests cavity-nesting birds, and its dispersal strongly depends on the movements of its host. Population genetic structure of I. arboricola was studied with seven polymorphic microsatellite markers. We collected 268 ticks from 76 nest boxes in four woodlots near Antwerp, Belgium. These nest boxes are mainly used by the principal hosts of I. arboricola, the great tit Parus major and the blue tit Cyanistes caeruleus. As these birds typically return to the same cavity for roosting or breeding, ticks within nest boxes were expected to be highly related, and tick populations were expected to be spatially structured among woodlots and among nest boxes within woodlots. In line with the expectations, genetic population structure was found among woodlots and among nest boxes within woodlots. Surprisingly, there was considerable genetic variation among ticks within nest boxes. This could be explained by continuous gene flow from ticks from nearby tree holes, yet this remains to be tested. A pairwise relatedness analysis conducted for all pairs of ticks within nest boxes showed that relatedness among larvae was much higher than among later instars, which suggests that larvae are the most important instar for tick dispersal. Overall, tick populations at the studied spatial scale are not as differentiated as predicted, which may influence the scale at which host-parasite evolution occurs. [ABSTRACT FROM AUTHOR]

Investigation of endo-macroparasite infections in living animals relies mostly on indirect methods aimed to detect parasite eggs in hosts' faeces. However, faecal flotation does not provide quantitative information on parasite loads, whereas faecal egg count (FEC) techniques may not give reliable estimates of parasite intensity, since egg production may be affected by density-dependent effects on helminth fecundity. We addressed this issue using Eastern grey squirrels ( Sciurus carolinensis) and their gastrointestinal nematode Strongyloides robustus to assess the performance of coprological techniques and to investigate factors affecting parasite fecundity. We compared results of gut examination, flotation and McMaster FECs in 65 culled grey squirrels. Sensitivity and specificity of flotation were 81.2 % (Confidence Interval, CI 54.3-95.9 %) and 85.7 % (CI 72.7-94.1 %), respectively, resulting in low positive predictive values when infection prevalence is low. Individual parasite fecundity (no. of eggs/adult female worm) was negatively affected by S. robustus intensity, leading to a non-linear relationship between parasite load and eggs/gram of faeces (EPG). As a consequence, whereas flotation may be a valid method to perform the first screening of infection status, FECs are not a reliable method to estimate S. robustus intensity, since diverse values of EPG may correspond to the same number of parasites. Neither the amount of analysed faeces nor the season had any effect on EPG, indicating that the observed reduction in helminth fecundity is likely caused exclusively by density-dependent processes such as competition among worms or host immune response. [ABSTRACT FROM AUTHOR]

Persistence of forest-dependent species in fragmented landscapes strongly relies on sufficient dispersal between patches, making it important to understand how animal movements are affected by the intervening matrix. Movements can be influenced through selection or avoidance of land cover based on their perceived suitability for foraging or providing cover. The composition and configuration of the matrix will, therefore, most likely be an important factor to consider when estimating connectivity between patches. To address this, we performed translocation experiments to understand how forest birds used different land cover types in a fine-grained matrix of a fragmented Afromontane biodiversity hot spot ( Taita Hills, Kenya). Our results revealed that use of land cover types for both the forest specialist Cabanis's greenbul Phyllastrephus cabanisi and for the forest generalist white-starred robin Pogonocichla stellata was disproportional to their availability. However, this effect was influenced by matrix configuration; in patchy matrices, land cover selection was more pronounced compared with more uniform matrices, especially for the forest specialist. At the scale of movement steps, risk avoidance seemed to be a strong factor in the route decisions for both species. Observed steps contained on average lower proportions of open land cover and did less frequently intersect built-up areas than expected. P. stellata did not differentiate between the alternative land cover types, whereas P. cabanisi preferred steps that contained more indigenous forest. The observed negative relationship between degree of forest dependency and matrix permeability implies that for members of the Taita bird community, which are even more dependent on intact forest habitat (i.e. the critically endangered Taita thrush Turdus helleri), current permeability of the matrix may be even lower. Matrix restoration to improve connectivity may, therefore, be a crucial instrument for the long-term survival of forest-dependent species in these fragmented Afromontane landscapes. [ABSTRACT FROM AUTHOR]

Red squirrels (Sciurus vulgaris) are widely distributed throughout Eurasia, occurring in many types of coniferous and mixed-deciduous forests. In fragmented landscapes, small and partly isolated populations with low immigration rates show reduced genetic diversity, but reforestation can increase gene flow and restore levels of genetic variation in a few decades. No studies have so far investigated the genetic structure of red squirrel in large, continuous forests. The Italian Alps are presently characterized by almost continuous, recently reconnected forest habitats, that were affected by deep landscape changes during last glaciations but remained mostly unchanged between 10 000 and 200 yearsbp, when forest cover was heavily reduced. In this study we analyse patterns of genetic variability of red squirrels in and between seven sites distributed over 250 km of Alpine habitat, using mitochondrial DNA (mtDNA) and microsatellites. We use isolation-by-distance (IBD) models to investigate the relative importance that past (Pleistocene glaciations) and recent (fragmentation, bottlenecks) events had on the present genetic situation. Both nuclear and mtDNA data indicate a significant differentiation among study sites and a significant correlation between genetic and geographical distance only over a large scale. No recent bottlenecks are recorded through microsatellites and demographic models strongly support equilibrium between gene flow and drift; however, mtDNA suggests that there may have been local demographic crashes, probably in correspondence with the 19th-century forest fragmentation. These findings indicate that local landscape factors other than geographical distance per se, such as barriers of unsuitable habitat, affect gene flow and determine differentiation. [ABSTRACT FROM AUTHOR]

Summary 1. Neotropical bat communities are characterized by a broad species diversity, which can be achieved and maintained only through partitioning of the available resources. 2. Here patterns of trophic resource utilization within a single neotropical savanna bat community are investigated. Moreover, the physical properties of food items (i.e. hardness), its variation with food size, and whether food hardness differs between items consumed by the bats in this community are investigated experimentally. 3. The results show that food hardness increases with the size of the food item, and that distinct differences exist in the amount of force needed to crush different food items (beetles vs other insects vs fruits). 4. Using previously published data on bite forces from species in the same community it is explored whether food hardness may play a role in shaping the diets of the bats in the community. The combined data on bite forces and food hardness indicate that food hardness can both directly and indirectly limit dietary diversity in bats. 5. The results also indicate that dietary specialization may potentially result in a decrease in trophic breadth for some species through its effect on bite performance. [ABSTRACT FROM AUTHOR]

abstract: For populations with a density-dependent life history reproducing at discrete annual intervals, we analyze small or moderate fluctuations in population size around a stable equilibrium, which is applicable to many vertebrate populations. Using a life history having age at maturity a , with stochasticity and density dependence in adult recruitment and mortality, we derive a linearized autoregressive equation with time lags from 1 to a yr. Contrary to current interpretations, the coefficients corresponding to different time lags in the autoregressive dynamics are not simply measures of delayed density dependence but also depend on life-history param-eters. The theory indicates that the total density dependence in a life history, D, should be defined as the negative elasticity of population growth rate per generation with respect to change in population size, where l is the asymptotic multiplicative growth... [ABSTRACT FROM AUTHOR]

As habitat disturbance and inbreeding increasingly stress natural populations, ecologists are in urgent need of simple estimators to measure their impact. It has been argued that developmental instability (DI) could be such a measure. Observed associations between DI and environmental or genetic stress, however, are largely inconsistent. We here test whether an interaction between habitat disturbance and inbreeding could, at least partly, explain these discordant patterns. We therefore studied individual estimates of fluctuating asymmetry (FA) and of inbreeding in three populations of the critically endangered Taita thrush that are differentially exposed to habitat disturbance following severe forest fragmentation. As predicted, the relationship between DI and inbreeding was pronounced under high levels of disturbance, but weak or nonexistent under less disturbed conditions. Examining this relationship with mean d2, an allelic distance estimator assumed to reflect ancestral inbreeding, did not reveal any significant trend, hence suggesting that inbreeding effects in the Taita thrush are fairly recent. [ABSTRACT FROM AUTHOR]