Harri Valdmann

Combined use of maternal, paternal and bi-parental genetic markers for the identification of wolf–dog hybrids

The identification of hybrids is often a subject of primary concern for the development of conservation and management strategies, but can be difficult when the hybridizing species are closely related and do not possess diagnostic genetic markers. However, the combined use of mitochondrial DNA (mtDNA), autosomal and Y chromosome genetic markers may allow the identification of hybrids and of the direction of hybridization. We used these three types of markers to genetically characterize one possible wolf–dog hybrid in the endangered Scandinavian wolf population. We first characterized the variability of mtDNA and Y chromosome markers in Scandinavian wolves as well as in neighboring wolf populations and in dogs. While the mtDNA data suggested that the target sample could correspond to a wolf, its Y chromosome type had not been observed before in Scandinavian wolves. We compared the genotype of the target sample at 18 autosomal microsatellite markers with those expected in pure specimens and in hybrids using assignment tests. The combined results led to the conclusion that the animal was a hybrid between a Scandinavian female wolf and a male dog. This finding confirms that inter-specific hybridization between wolves and dogs can occur in natural wolf populations. A possible correlation between hybridization and wolf population density and disturbance deserves further research.

Mitogenetic structure of brown bears (Ursus arctos L.) in northeastern Europe and a new time frame for the formation of European brown bear lineages

We estimated the phylogenetic relationships of brown bear maternal haplotypes from countries of northeastern Europe (Estonia, Finland and European Russia), using sequences of mitochondrial DNA (mtDNA) control region of 231 bears. Twenty‐five mtDNA haplotypes were identified. The brown bear population in northeastern Europe can be divided into three haplogroups: one with bears from all three countries, one with bears from Finland and Russia, and the third composed almost exclusively of bears from European Russia. Four haplotypes from Finland and European Russia matched exactly with haplotypes from Slovakia, suggesting the significance of the current territory of Slovakia in ancient demographic processes of brown bears. Based on the results of this study and those from the recent literature, we hypothesize that the West Carpathian Mountains have served either as one of the northernmost refuge areas or as an important movement corridor for brown bears of the Eastern lineage towards northern Europe during or after the last ice age. Bayesian analyses were performed to investigate the temporal framework of brown bear lineages in Europe. The molecular clock was calibrated using Beringian brown bear sequences derived from radiocarbon‐dated ancient samples, and the estimated mutation rate was 29.8% (13.3%−47.6%) per million years. The whole European population and Western and Eastern lineages formed about 175 000, 70 000 and 25 000 years before present, respectively. Our approach to estimating the time frame of brown bear evolution demonstrates the importance of using an appropriate mutation rate, and this has implications for other studies of Pleistocene populations.

Sudden expansion of a single brown bear maternal lineage across northern continental Eurasia after the last ice age: a general demographic model for mammals?

The brown bear has proved a useful model for studying Late Quaternary mammalian phylogeography. However, information is lacking from northern continental Eurasia, which constitutes a large part of the species’ current distribution. We analysed mitochondrial DNA sequences (totalling 1943 bp) from 205 bears from northeast Europe and Russia in order to characterize the maternal phylogeography of bears in this region. We also estimated the formation times of the sampled brown bear lineages and those of its extinct relative, the cave bear.

Differentiation and levels of genetic variation in northern European lynx (Lynx lynx) populations revealed by microsatellites and mitochondrial DNA analysis

The European lynx (Lynx lynx) hasexperienced significant decline in populationnumbers over large parts of its formerdistribution area in central and northernEurope. In Scandinavia (Sweden and Norway), thespecies has been subject to intense hunting and inthe early 20th century the population size mayhave been as low as about 100 animals. Duringthe rest of the century there have beenalternating periods of restricted hunting andtotal protection. Future management of theScandinavian lynx population will requireinsight into what effects demographicbottlenecks may have had on genetic variabilityand structure. For this purpose, 276 lynxesfrom Sweden, Norway, Finland, Estonia andLatvia were analysed for polymorphism at 11feline microsatellite loci and at themitochondrial DNA (mtDNA) control region.Scandinavian lynxes were found to be fixed fora single mtDNA haplotype, while this and threeadditional haplotypes were seen in Finland andthe Baltic States (Estonia and Latvia); thehaplotypes were all very similar, onlydiffering at 1–4 sites within a 700 bp regionsequenced. Microsatellite variability wasmoderate (He = 0.51–0.62) with lowerheterozygosity and fewer alleles in Scandinaviathan in Finland and the Baltic States together,though significant so only for the latter.Heterozygosity data in Scandinavia wereconsistent with a recent population bottleneck.Various analyses (e.g. Fst, individual-basedtree, assignment test) revealed distinctgenetic differentiation between Scandinavianlynxes and animals from Finland and the BalticStates. Some structure was evident withinScandinavia as well, suggesting an isolation bydistance. The observed partition of geneticvariability between Scandinavia and the easterncountries thereof indicates that lynxpopulations from the two regions may need to beseparately managed. We discuss what factors canhave contributed to the population geneticstructure seen in northern European lynxpopulations of today.

Winter diets of wolfCanis lupus and lynxLynx lynx in Estonia and Latvia

Winter diets of wolfCanis lupus Linnaeus, 1758 and lynxLynx lynx Linnaeus, 1758 in Latvia and Estonia were investigated in 1997–2000 based on stomach contents of hunted animals and scats. Ungulates appeared to be the staple food for both predators. Lynx diet to a high extent consisted of cervids (Estonia 52% frequency of prey, Latvia 88%), roe deer dominating. Mountain hareLepus timidus made up from 9% (Latvia) to 31% (Estonia) of the lynx diet, and red foxVulpes vulpes 7% in Estonian sample. Wolf diet was more diverse; besides cervids (44% in Latvia, 63% in Estonia) it included wild boar Sus scrofa (32% in Latvia, 17% in Estonia), carrion, small rodents, and other food items. Proportion of empty stomachs was high both in wolves (37%) and lynxes (35%) in Latvia. Range of stomach content weights varied from zero to more than 4 kg in wolves and almost 1.5 kg in lynx. Pianka’s indices of food niche overlapped significantly between species and countries (0.85–0.99).

Carnivory is Positively Correlated with Latitude among Omnivorous Mammals: Evidence from Brown Bears, Badgers and Pine Martens

Omnivores exploit numerous sources of protein and other nutrients throughout the year, and meat is generally considered a high-quality resource. However, it is unknown if there is any general association between latitude and carnivorous behavior in omnivorous mammals. We examined the relative importance of meat and other dietary components, including anthropogenic food items, in the diet of brown bears (Ursus arctos) in Estonia using conventional scat- and stomach-content analyses as well as stable-isotope (&dgr;15N, &dgr;13C) analyses. When food habits of brown bears in Estonia were compared with those of other populations in central and northern Europe, the proportion of animal prey in the diet was positively correlated with latitude. Further comparison with the data on the diet of two other omnivorous mammals, the European badger (Meles meles) and the European pine marten (Martes martes), provides evidence that increased carnivory towards northern latitudes may be a general adaptation in omnivorous mammals.

First report of the zoonotic tapeworm Echinococcus multilocularis in raccoon dogs in Estonia, and comparisons with other countries in Europe.

The raccoon dog (Nyctereutes procyonoides) is an alien species in Europe and an important vector of zoonotic diseases. However, compared to the red fox (Vulpes vulpes), less attention has been paid to the raccoon dog as a potentially important host for Echinococcus multilocularis, the infective agent of alveolar echinococcosis, which is an emerging infectious disease with a high mortality rate. We examined the small intestines of 249 Estonian raccoon dogs and found 1.6% of individuals to be infected with E. multilocularis. The relatively large difference between this prevalence and that found in sympatric red foxes (31.5%) sampled during the same time period might be due to differences in diet: red foxes consume significantly more arvicolid rodents - the main intermediate hosts of the parasite - especially during the coldest period of the year when raccoon dogs hibernate. Nonetheless, given the relatively high density of raccoon dogs, our results suggest that the species also represents an important definitive host species for E. multilocularis in Estonia. Compared with other countries in Europe where E. multilocularis-infected raccoon dogs have been recorded (Latvia, Lithuania, Poland, Germany, and Slovakia), the prevalence in Estonia is low. The longer hibernation period of raccoon dogs at higher latitudes may explain this pattern. Both mitochondrial and nuclear loci were analysed for Estonian isolates: based on EmsB microsatellite genotyping the Estonian isolates shared an identical genotype with E. multilocularis in northern Poland, suggesting a common history with this region. The data from more than a quarter of the mitochondrial genome (3558 bp) revealed two novel haplotypes specific to Estonia and placed them into the same haplogroup with isolates from other European regions. Considering that the raccoon dog is becoming increasingly widespread and is already relatively abundant in several countries in Europe, the role of the species must be taken into account when assessing the E. multilocularis related risks to public health.

Winter Diet and Movements of Wolf (Canis Lupus) in Alampedja Nature Reserve, Estonia

Wolf (Canis lupus) diet was studied in Alam-Pedja Nature Reserve from October to April 1999–2001. 119 wolf scats were collected and analysed. Remains of eight mammal species were found in wolf scats of which ungulates formed nearly 80%. Wolf diet in the nature reserve consisted mainly of wild boar (Sus scrofa; 37%), moose (Alces alces; 30.5%) and roe deer (Capreolus capreolus; 12.1%). A proportion of moose in ungulate biomass was calculated to be 77.5%; wild boar 20.4% and roe deer only 2%. It was found that wolf diet in the nature reserve differed from that of Estonia in general. We have concluded, that in areas with insufficient roe deer availability, wild boar and moose form the main prey items for wolf. It was suggested, that pack movements in area are mostly influenced by the localisation of prey animals and controlling of pack territory.

Alien species and their zoonotic parasites in native and introduced ranges: The raccoon dog example.

The raccoon dog (Nyctereutes procyonoides) is a canid that is indigenous in East Asia and alien in Europe, where it was introduced more than half a century ago. The aim of this study was to compare the parasite faunas associated with raccoon dogs in their native and introduced ranges, and to identify zoonotic parasite species. We examined 255 carcasses of hunted raccoon dogs from Estonia and recorded a total of 17 helminth species: 4 trematodes, 4 cestodes and 9 nematodes. The most prevalent parasite species were Uncinaria stenocephala (97.6%) and Alaria alata (68.3%). Average parasite species richness was 2.86 (the highest was 9) and only two animals were not parasitized at all. Although the infection intensity was determined by weight and not by sex, all animals infected with more than five helminth species were males. We also found that animals infected with higher numbers of helminth species fed significantly more on natural plants. Intentional consumption of grass may represent a self-medicating behaviour among raccoon dogs. We included the Estonian data into a wider comparison of raccoon dog parasite faunas and found a total of 54 helminth taxa, including 28 of zoonotic potential. In Europe, raccoon dogs are infected with a minimum of 32 helminth species of which 19 are zoonotic; in the native range they are infected with 26 species of which 17 are zoonotic. Most species were nematodes or trematodes, with fewer cestodes described. The recent increase in the number and range of raccoon dogs in Europe and the relatively high number of zoonotic parasite taxa that it harbours suggests that this species should be considered an important source of environmental contamination with zoonotic agents in Europe.

Winter severity or supplementary feeding—which matters more for wild boar?

During recent decades, wild boar have successfully colonised areas previously believed to be unsuitable for the species. Estonia lies close to the northern limit of the species range, and mast foods, which are a common natural food source for many wild boar populations, are practically absent. We hypothesised that the proportion of cultivated area and especially supplementary feeding, which is widely used in Estonia to lower the winter mortality of game species, play important roles in sustaining the local wild boar population. To determine the most important factors shaping the abundance of wild boar in a northern environment, we developed mixed models to account for variation in an index of wild boar abundance (AI) based on winter track counts. The abundance of supplementary feeding sites and mean January temperature were the most important factors determining wild boar winter abundance. We conclude that the current high local population density is sustained by intensive supplementary feeding, which has exceeded the limiting effect of harsh winters.