Petter Kjellander | Swedish University of Agricultural Sciences (original) (raw)

Papers by Petter Kjellander

Research Square (Research Square), Jul 13, 2022

Background Wildlife hosts may serve as reservoirs for strongyles which can be transmitted to dome... more Background Wildlife hosts may serve as reservoirs for strongyles which can be transmitted to domestic livestock. Therefore, we aimed to assess the risk for transmission of important nematode pathogens to domestic sheep in Sweden. The main aim of the study was to assess the risk for transmission of important pathogens from four wildlife hosts to domestic sheep. Methods First, fecal samples were collected from roe deer (n = 125), fallow deer (n = 106), red deer (n = 18) and mouflon (n = 13) in south central Sweden during the hunting season in 2019. Second, after fecal examination samples were cultured and the larvae were harvested, followed by DNA extractions. Third, all samples were then barcoded and processed for sequence analysis on the PacBio platform. Finally, bioinformatic sequence analysis was conducted with DADA2, while species diversity and richness as well as interactions between the different hosts were calculated and analyzed in R. Results Nematode ITS2 sequences were found in 225 of 262 (86%) samples. In total 31 taxa were identified amongst which 26 (86%) to the species level These were found in different combinations, amongst which 24 (77%) occurred in roe deer, 19 (61%) in fallow deer, 20 (65%) in red deer, and 10 (32%) in mouflon. Only five species are known to be associated with livestock (Chabertia ovina, Haemonchus contortus, Oesophagostomum venulosum, Teladorsagia circumcincta and Trichostrongylus axei). However, in the present study the relative abundance and prevalence of most of these species were low. The most striking exception was T. axei which was relatively abundant in all wildlife hosts. In addition, a wide range of wildlife specific nematodes such as Ostertagia leptospicularis and Spiculopteragia spp. were identified including the invasive nematode Spiculopteragia houdemeri which was found for the first time in red deer, fallow deer, and mouflon in Sweden. The difference in the number of shared species between mouflon and all cervids (n = 6) was less than between all three cervids (n = 8). Conclusion In contrast to our previous study with sheep, the relative abundance and prevalence of T. axei was generally much higher in wildlife than both H. contortus, and T. circumcincta which were negligible. Although the risk for cross-infections of nematodes between the studied wildlife hosts and sheep in Sweden cannot be ruled out, our findings indicate that the transmission potential appear to be relatively low for H. contortus and T. circumcincta, which are the two most pathogenic species in sheep.

Zoonoses and Public Health, May 29, 2023

Ixodes ricinus ticks are Scandinavia's main vector for tick‐borne encephalitis virus (TBEV), ... more Ixodes ricinus ticks are Scandinavia's main vector for tick‐borne encephalitis virus (TBEV), which infects many people annually. The aims of the present study were (i) to obtain information on the TBEV prevalence in host‐seeking I. ricinus collected within the Øresund‐Kattegat‐Skagerrak (ØKS) region, which lies in southern Norway, southern Sweden and Denmark; (ii) to analyse whether there are potential spatial patterns in the TBEV prevalence; and (iii) to understand the relationship between TBEV prevalence and meteorological factors in southern Scandinavia. Tick nymphs were collected in 2016, in southern Scandinavia, and screened for TBEV, using pools of 10 nymphs, with RT real‐time PCR, and positive samples were confirmed with pyrosequencing. Spatial autocorrelation and cluster analysis was performed with Global Moran's I and SatScan to test for spatial patterns and potential local clusters of the TBEV pool prevalence at each of the 50 sites. A climatic analysis was made to correlate parameters such as minimum, mean and maximum temperature, relative humidity and saturation deficit with TBEV pool prevalence. The climatic data were acquired from the nearest meteorological stations for 2015 and 2016. This study confirms the presence of TBEV in 12 out of 30 locations in Denmark, where six were from Jutland, three from Zealand and two from Bornholm and Falster counties. In total, five out of nine sites were positive from southern Sweden. TBEV prevalence of 0.7%, 0.5% and 0.5%, in nymphs, was found at three sites along the Oslofjord (two sites) and northern Skåne region (one site), indicating a potential concern for public health. We report an overall estimated TBEV prevalence of 0.1% in questing I. ricinus nymphs in southern Scandinavia with a region‐specific prevalence of 0.1% in Denmark, 0.2% in southern Sweden and 0.1% in southeastern Norway. No evidence of a spatial pattern or local clusters was found in the study region. We found a strong correlation between TBEV prevalence in ticks and relative humidity in Sweden and Norway, which might suggest that humidity has a role in maintaining TBEV prevalence in ticks. TBEV is an emerging tick‐borne pathogen in southern Scandinavia, and we recommend further studies to understand the TBEV transmission potential with changing climate in Scandinavia.

Journal of Animal Ecology, Dec 26, 2019

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial-NoDerivatives| 4.0 International License

Ecological Monographs, Mar 23, 2017

Partial migration, when only part of the population migrates seasonally while the other part rema... more Partial migration, when only part of the population migrates seasonally while the other part remains resident on the shared range, is the most common form of migration in ungulates. Migration is often defined by spatial separation of seasonal ranges and consequently, classification of individuals as migrants or residents is usually only based on geographic criteria. However, the underlying mechanism for migration is hypothesized to be movement in response to spatiotemporal resource variability and thus, migrants are assumed to travel an "ecological distance" (ED) or shift their realized ecological niches. While ecological and geographic distances should be related, their relationship may depend on landscape heterogeneity. Here, we tested the utility of ecological niche theory to both classify migratory individuals and to understand the underlying ecological factors for migratory behavior. We developed an integrative approach combining measures in geographic and ecological niche space and used this to classify and explain migratory behavior of 71 annual roe deer (Capreolus capreolus) movement trajectories in five European study areas. First, to assess the utility of the ED concept for classifying migratory behavior, we tested whether roe deer sought the same ecological conditions year-round or moved to different ecological conditions by measuring the annual ED travelled and the seasonal niche overlap using multivariate statistics. Comparing methods to classify migrants and residents based on geographic and ecological niche space, we found that migratory roe deer switched between seasons both in geographic and in ecological dimensions. Second, we tested which seasonal ecological factors separated resident from migrant niches using discriminant analysis and which broad-scale determinants (e.g., spatiotemporal forage variation and population density) predicted migration probability using generalized linear models. Our results indicated that factors describing forage and topographic variability discriminated seasonal migrant from resident niches. Determinants for predicting migration probability included the temporal variation (seasonality) and also the spatial variability of forage patches. Last, we also found suggestive evidence for a positive relationship between population density and migration probability. By applying the ecological niche concept to the study of partial migration in ungulates, our work underlines that partial migration is a form of behavioral plasticity.

Forests are of major importance to human society, contributing several crucial ecosystem services... more Forests are of major importance to human society, contributing several crucial ecosystem services. Biodiversity is suggested to positively influence multiple services but evidence from natural systems at scales relevant to management is scarce. Here, across a scale of 400,000 km 2 , we report that tree species richness in production forests shows positive to positively hump-shaped relationships with multiple ecosystem services. These include production of tree biomass, soil carbon storage, berry production and game production potential. For example, biomass production was approximately 50% greater with five than with one tree species. In addition, we show positive relationships between tree species richness and proxies for other biodiversity components. Importantly, no single tree species was able to promote all services, and some services were negatively correlated to each other. Management of production forests will therefore benefit from considering multiple tree species to sustain the full range of benefits that the society obtains from forests.

Pathogens, Oct 25, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Epidemiology and Infection, Mar 2, 2017

Scandinavian Journal of Forest Research, Apr 7, 2014

The accuracy of the Content should not be relied upon and should be independently verified with p... more The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 10, 2005

Swedish University of Agricultural Sciences eBooks, Jun 1, 2021

The increasing wild boar population in Sweden, and in many other parts of Europe, has led to new ... more The increasing wild boar population in Sweden, and in many other parts of Europe, has led to new conflicts among many stakeholders. Damages on agricultural crops, rooting on grass fields and more wildlife collisions with cars are some of the results of a larger wild boar population. This sets high demands on the management of the species in order to reduce the damages and the costs. It is therefore essential to have a good estimate of the number of animals in the population. Wild boars are due to their nature not easily counted through general inventory methods. This study evaluates two methods that are deemed suitable for wild boars; simultaneous observations (by humans) and wildlife cameras, both at feeding stations. The study is based on movement patterns from GPSmarked wild boars in Sweden that were analyzed in the program ArcGis. The results indicate that simultaneous observations on an average will detect 2,3-3,6 times more animals than a wildlife camera does for the same period. The two methods can therefore be combined during an inventory once the detection rate is known for both of them. The proportion of the population that are being observed are likely to vary over the year and different locations. Surveys performed in forest dominated areas seem to detect more wild boars than surveys in agricultural landscape and wild boars also tends to visit the feeding stations more frequently during the winter. For this study, an increased number of observation sites didn't have major impact on the percentage of animals observed.

Behavioural Processes, Jul 1, 2016

The risk allocation hypothesis predicts that vigilance should be adjusted to the temporal variati... more The risk allocation hypothesis predicts that vigilance should be adjusted to the temporal variation in risk. We test this hypothesis in wild fallow deer exposed to short term (disturbance) and long term (presence of a fawn after parturition) changes in risk. We recorded the proportion, frequency and type of vigilance and size of used area before and after parturition, in GPS-collared wild female fallow deer. Vigilance was divided in two main groups: "non-grazing vigilance" and "grazing vigilance". The latter group was divided into "grazing vigilance while chewing" and a "grazing vigilance when chewing was interrupted". By recording external disturbance in form of passing cars, we were able to investigate if this altered the amount, and type of vigilance. We found that females increased the proportion and frequency of "grazing vigilance stop chewing" after parturition. The "grazing vigilance chewing" was unaffected, but "nongrazing vigilance" decreased. Disturbance increased the proportion "grazing vigilance stop chewing" to the same extent before and after parturition. We found a clear decrease in female home range size after parturition as a possible behavioural adjustment. The increase in "grazing vigilance stop chewing" after parturition is a rarely described but expected cost of reproduction.

Natural Resource Modeling, Sep 15, 2017

The aim of this paper is to analyze the optimal management of two ecologically interdependent, co... more The aim of this paper is to analyze the optimal management of two ecologically interdependent, competing species, roe deer (Capreolus capreolus) and fallow deer (Dama dama). To this end, we develop a numerical stagestructured model, accounting for species-specific life history characteristics, gender, and stage-specific hunting values. Two contrasting management regimes are considered: optimal joint management of the two species and management where the decision maker is ignorant about interspecific competition. Results from our case study show that the presence of interspecific competition reduces roe deer population size and harvest by 30% and 47%, respectively, and reduces the net present value by 9%. High interspecific competition could lead to the exclusion of the roe deer from the area. In contrast, ignorance about the level and consequences of interspecific competition has no impact on harvest decisions and revenues. The explanation is the higher hunting benefits for fallow deer. Summary for Managers • Wildlife managers need bioeconomic models for decisions on ecologically interdependent species. • This study investigates optimal joint management of roe and fallow deer when the fallow deer exerts a negative impact on roe deer due to interspecific competition.

BMC Veterinary Research, May 10, 2017

Background: To understand and reduce the concomitant effects of trapping and handling procedures ... more Background: To understand and reduce the concomitant effects of trapping and handling procedures in wildlife species, it is essential to measure their physiological impact. Here, we examined individual variation in stress levels in non-anesthetized European roe deer (Capreolus capreolus), which were captured in box traps and physically restrained for tagging, biometrics and bio-sampling. In winter 2013, we collected venous blood samples from 28 individuals during 28 capture events and evaluated standard measurements for stress (heart rate, body temperature, neutrophil to lymphocyte ratio, lactate and total cortisol). Additionally, we assessed stress using the immunological tool, Leukocyte Coping Capacity (LCC), a real-time proxy for stress measuring oxygen radical production by leukocytes. Finally, the behavioral response to handling was recorded using a scoring system. Results: LCC and therefore stress levels were negatively influenced by the time animals spent in the box trap with human presence at the capture site prior to handling. In contrast, none of the classical stress measures, including total cortisol, nor the behavioral assessment, were correlated with the stressor tested (time of human presence prior to handling) and thus did not provide a clear depiction regarding the extent of the animals short-term stress response. Conclusions: Overall our study verifies the LCC as a strong method to quantify short-term stress reactions in wildlife. Moreover, our results clearly show that human presence at the trapping site prior to handling should be kept to an absolute minimum in order to reduce stress levels.

European Journal of Wildlife Research, Feb 1, 2018

Animal welfare concerns are becoming a central issue in wildlife management and conservation. Thu... more Animal welfare concerns are becoming a central issue in wildlife management and conservation. Thus, we investigated stress response of wild ungulates to potentially traumatic situations (shooting injuries, vehicle collisions, entanglement, injuries or diseases) and hunting methods (stalking, battues and hunts with dogs) by means of serum cortisol concentrations from blood collected from killed animals. Cortisol levels in roe deer ranged below and in wild boar above levels for moose, red deer and fallow deer (hence, pooled as a group Bdeer^). Apart from species, cortisol concentration in trauma situations was mainly explained by trauma type and presence of disturbance after the trauma event. Effect of trauma type differed significantly for Bdeer^, with animals caught in fences and suffering vehicle collisions experiencing higher cortisol levels than animals injured by shooting. Differences between hunting methods were observed in the cervids (Bdeer^and roe deer), with stalking leading to lower cortisol levels than hunts with dogs (both groups) and battues (roe deer). Events both before and after the shot, such as duration of pursuit prior to shooting, location of injury, trauma length and presence of disturbance after the shot were relevant for cortisol levels in hunted cervids. Our results indicate that search teams tracking and euthanising wounded animals should behave in a calm way to minimise disturbance. Still, it is important to acknowledge that many situations described in the literature, i.e. reindeer handling, roe deer captures and red deer yarding, seem even more stressful, beside vehicle collisions, than most hunting methods.

Polar Biology, Sep 22, 2009

The Eurasian lynx (Lynx lynx) is a common predator of both roe deer (Capreolus capreolus) and rei... more The Eurasian lynx (Lynx lynx) is a common predator of both roe deer (Capreolus capreolus) and reindeer (Rangifer tarandus) in Sweden. We investigated the inXuence of prey availability, latitude, sex, and age on body size and body mass variation of the Eurasian lynx in Sweden, using data from 243 specimens whose locality of capture, year of capture, sex, and age were known. We found that both body size and body mass of the lynx in Sweden are mainly aVected by the lynx sex and age but also by the availability of prey during the Wrst year of life. Body size and body mass of lynx as well as the density of roe deer increased from Central Sweden to South. Furthermore, body size and body mass of lynx increased from Central Sweden to North (i.e. within the reindeer husbandry area). Lynx body size was slightly smaller within the reindeer husbandry area (approximately north of latitudes 62°-63°N) compared to outside, probably because reindeer are more diYcult prey to hunt, as well as being migratory and thus an unpredictable prey for the Eurasian lynx compared to the non-migratory roe deer. Our results support a growing body of evidence showing that food availability at growth has a major eVect on body size of animals.

PLOS ONE, Jun 20, 2016

Dietary choices are central to our understanding of ecology and evolution. Still, many aspects of... more Dietary choices are central to our understanding of ecology and evolution. Still, many aspects of food choice have been hampered by time consuming procedures and methodological problems. Faster and cheaper methods, such as DNA metabarcoding, have therefore been widely adopted. However, there is still very little empirical support that this new method is better and more accurate compared to the classic methods. Here, we compare DNA metabarcoding to macroscopic identifications of rumen contents in two species of wild free-ranging ungulates: roe deer and fallow deer. We found that the methods were comparable, but they did not completely overlap. Sometimes the DNA method failed to identify food items that were found macroscopically, and the opposite was also true. However, the total number of taxa identified increased using DNA compared to the macroscopic analysis. Moreover, the taxonomic precision of metabarcoding was substantially higher, with on average 90% of DNA-sequences being identified to genus or species level compared to 75% of plant fragments using macroscopy. In niche overlap analyses, presence/absence data showed that both methods came to very similar conclusions. When using the sequence count data and macroscopic weight, niche overlap was lower than when using presenceabsence data yet tended to increase when using DNA compared to macroscopy. Nevertheless, the significant positive correlation between macroscopic quantity and number of DNA sequences counted from the same plant group give support for the use of metabarcoding to quantify plants in the rumen. This study thus shows that there is much to be gained by using metabarcoding to quantitatively assess diet composition compared to macroscopic analysis, including higher taxonomic precision, sensitivity and cost efficiency.

HAL (Le Centre pour la Communication Scientifique Directe), 2009

An explanation for female multiple mating when males offer no material benefits but sperm remains... more An explanation for female multiple mating when males offer no material benefits but sperm remains elusive, largely because of a lack of empirical support for the genetic benefits hypothesis. We used 21 microsatellite markers to test for multiple paternities among 88 litters of roe deer, Capreolus capreolus, and to investigate the inbreeding avoidance hypothesis as a potential mechanism for the evolution of female multiple mating. From paternity analyses, we found that 13.5% of polytocous litters were sired by more than one male. We also found that a half-sib relationship was more likely than a full-sib relationship for 20.5% of all litters. This is the first report of multiple paternities in a territorial ungulate species. In support of the inbreeding avoidance hypothesis, we found that parents who were strongly related produced offspring with lower individual heterozygosity that survived less well during their first summer than fawns with unrelated parents. In addition, fawns from multiple paternity litters survived their first summer better than fawns from single paternity litters. However, it remains unclear whether all female multiple paternity events in this species are provoked by an initial consanguineous mating.