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opencc-zeroOct 2020View details →

Data from: Disentangling direct and indirect determinants of the duration of maternal care in brown bears: environmental context matters

The duration of maternal care, an important life history trait affecting population dynamics, varies greatly within species. Yet, our understanding of its predictors is limited, mostly correlative, and subject to misinterpretations, due to difficulties to disentangle the role of maternal- and offspring-related characteristics. We conducted path analysis on a dataset including 217 brown bear litters captured over a 29-year period in two populations in Sweden ("North" and "South") facing contrasting environmental conditions to identify and quantify the causes of variation in the duration of maternal care (1.5 years or 5 years).

opencc-zeroDec 2013View details →

Data from: Brown and polar bear Y chromosomes reveal extensive male-biased gene flow within brother lineages

Brown and polar bears have become prominent examples in phylogeography, but previous phylogeographic studies relied largely on maternally inherited mitochondrial DNA (mtDNA) or were geographically restricted. The male-specific Y chromosome, a natural counterpart to mtDNA, has remained under-explored. Although this paternally inherited chromosome is indispensable for comprehensive analyses of phylogeographic patterns, technical difficulties and low variability have hampered its application in most mammals. We developed 13 novel Y-chromosomal sequence and microsatellite markers from the polar bear genome, and screened these in a broad geographic sample of 130 brown and polar bears. We also analyzed a 390 kb-long Y-chromosomal scaffold using sequencing data from published male ursine genomes. Y chromosome evidence support the emerging understanding that brown and polar bears started to diverge no later than the Middle Pleistocene. Contrary to mtDNA patterns, we found (i) brown and polar bears to be reciprocally monophyletic sister (or rather brother) lineages, without signals of introgression, (ii) male-biased gene flow across continents and on phylogeographic time scales, and (iii) male dispersal that links the Alaskan ABC-islands population to mainland brown bears. Due to female philopatry, mtDNA provides a highly structured estimate of population differentiation, while male-biased gene flow is a homogenizing force for nuclear genetic variation. Our findings highlight the importance of analyzing both maternally and paternally inherited loci for a comprehensive view of phylogeographic history, and that mtDNA-based phylogeographic studies of many mammals should be re-evaluated. Recent advances in sequencing technology render the analysis of Y chromosomal variation feasible, even in non-model organisms.

Data from: Movement ecology of brown bears (Ursus arctos) in the Romanian Eastern Carpathians

Brown bear movement patterns are driven by their opportunistic feeding behaviour, with their complex life history and seasonality playing an important role in habitat selection. Within a large unfragmented forest habitats persisting over decades in the Romanian Carpathians and a prohibitive hunting management during 40 years of communist centralised game management, information about brown bear movements and spatial ecology is lacking. Using data obtained from 13 brown bears fitted with GPS telemetry collars, we estimated home ranges and core activity areas and we investigated the daily, seasonal and altitudinal movements of brown bears in the Eastern Romanian Carpathians and surrounding high hills. The median MCP95% home ranges of brown bears was 629.92 km2 and the median size of core activity areas (estimated as 50% kernel density) was 36.37 km2, with no significant differences between males and females. The mean daily distance travelled, measured as daily displacement length, was 1818 m and an analysis of seasonal movements indicated significant differences between seasons (greatest movements during the Hyperphagia season). The GPS-collared brown bears travelled between a minimum altitude measured at ~234 m and a maximum at ~1634 m. Analysing the spatial overlap between the estimated home range and the game management units (GMU) limits, we obtained a median number of 8 GMUs overlapping totally or partially with estimated home range polygons. Our study, using GPS telemetry, highlights the complex spatial ecology of the brown bear in the Romanian Carpathians, with larger home range size than those estimated in other European brown bear populations and with daily movements that vary by season and within a large altitude range. Our study supports the implementation of brown bear monitoring at a regional scale, rather than focusing on county level GMUs as the monitoring unit.

Data from: Habitat segregation between brown bears and gray wolves in a human-dominated landscape

Identifying how sympatric species belonging to the same guild coexist is a major question of community ecology and conservation. Habitat segregation between two species might help reduce the effects of interspecific competition and apex predators are of special interest in this context, because their interactions can have consequences for lower trophic levels. However, habitat segregation between sympatric large carnivores has seldom been studied. Based on monitoring of 53 brown bears (Ursus arctos) and 7 sympatric adult gray wolves (Canis lupus) equipped with GPS collars in Sweden, we analyzed the degree of interspecific segregation in habitat selection within their home ranges in both late winter and spring, when their diets overlap the most. We used the K-select method, a multivariate approach that relies on the concept of ecological niche, and randomization methods to quantify habitat segregation between bears and wolves. Habitat segregation between bears and wolves was greater than expected by chance. Wolves tended to select for moose occurrence, young forests, and rugged terrain more than bears, which likely reflects the different requirements of an omnivore (bear) and an obligate carnivore (wolf). However, both species generally avoided human-related habitats during daytime. Disentangling the mechanisms that can drive interspecific interactions at different spatial scales is essential for understanding how sympatric large carnivores occur and coexist in human-dominated landscapes, and how coexistence may affect lower trophic levels. The individual variation in habitat selection detected in our study may be a relevant mechanism to overcome intraguild competition and facilitate coexistence.

opencc-zeroDec 2010View details →

Data from: Monitoring the effective population size of a brown bear (Ursus arctos) population using new single-sample approaches

The effective population size (Ne) could be the ideal parameter for monitoring populations of conservation concern as it conveniently summarizes both the evolutionary potential of the population and its sensitivity to genetic stochasticity. However, tracing its change through time is difficult in natural populations. We applied four new methods for estimating Ne from a single sample of genotypes to trace temporal change in Ne for bears in the Northern Dinaric Mountains. We genotyped 510 bears using 20 microsatellite loci, and determined their age. The samples were organized into cohorts with regard to the year when the animals were born and yearly samples with age categories for every year when they were alive. We used the Estimator by Parentage Assignment (EPA) to directly estimate both Ne and generation interval for each yearly sample. For cohorts, we estimated the effective number of breeders (Nb) using Linkage Disequilibrium, Sibship Assignment and Approximate Bayesian Computation methods, and extrapolated these estimates to Ne using the generation interval. The Ne estimate by EPA is 276 (183-350 95% CI), meeting the inbreeding-avoidance criterion of Ne > 50 but short of the long-term minimum viable population goal of Ne > 500. The results obtained by the other methods are highly consistent with this result, and all indicate a rapid increase in Ne probably in the late 1990s and early 2000s. The new single-sample approaches to estimation of Ne provide efficient means for including Ne in monitoring frameworks, and will be of great importance for future management and conservation.

Data from: Alaskan brown bears (Ursus arctos) aggregate and display fidelity to foraging neighborhoods while preying on Pacific salmon along small streams

The interaction between brown bears (Ursus arctos) and Pacific salmon (Oncorhynchus spp.) is important to the population dynamics of both species and a celebrated example of consumer-mediated nutrient transport. Yet, much of the site-specific information we have about the bears in this relationship comes from observations at a few highly visible but unrepresentative locations and a small number of radio-telemetry studies. Consequently, our understanding of brown bear abundance and behavior at more cryptic locations where they commonly feed on salmon, including small spawning streams, remains limited. We employed a non-invasive genetic approach (barbed wire hair snares) over four summers (2012-2015) to document patterns of brown bear abundance and movement among six spawning streams for sockeye salmon, O. nerka, in southwestern Alaska. The streams were grouped into two trios on opposite sides of Lake Aleknagik. Thus, we predicted that most bears would forage within only one trio during the spawning season because of the energetic costs associated with swimming between them or traveling around the lake, and show fidelity to particular trios across years because of the benefits of familiarity with local salmon dynamics and stream characteristics. Huggins closed-capture models based on encounter histories from genotyped hair samples revealed that as many as 41 individuals visited single streams during the annual six-week sampling season. Bears also moved freely among trios of streams but rarely moved between these putative foraging neighborhoods, either during or between years. By implication, even small salmon spawning streams can serve as important resources for brown bears, and consistent use of stream neighborhoods by certain bears may play an important role in spatially structuring coastal bear populations. Our findings also underscore the efficacy of non-invasive hair snagging and genetic analysis for examining bear abundance and movements at relatively fine spatial and temporal scales.

Data from: Optimal foraging or surplus killing: selective consumption and discarding of salmon by brown bears

Selective consumption of prey by predators, observed in many animals, is often attributed to optimal foraging. Consistent with this idea, brown bears (Ursus arctos) often exhibit partial consumption, feeding exclusively on lipid-rich tissues of Pacific salmon (Oncorhynchus spp.), and discarding remains. However, bears also kill and abandon salmon without consuming any tissue. These discarded fish may be consistent with optimal foraging choices if they are of poor quality and if bears have easy access to better prey, or may reveal non-adaptive surplus killing behavior if fish are killed and discarded at random or solely based on prey abundance. Using 21 consecutive years of data from sockeye salmon (O. nerka) carcass surveys in Alaska, we found that foraging to maximize energy intake best explained prey discarding behavior. Specifically, discarding was more common under high prey abundance, late in the salmon run, and with low quality prey. Patterns of tissue consumption were consistent with these findings; bears were less likely to consume belly, body, and brain tissue when prey condition decreased. Other factors not quantified here (e.g., bear demography, alternative food resources) almost certainly influence prey discard and partial consumption, though the salmon-related factors explored here strongly influenced bear foraging decisions that were consistent with optimal foraging theory. We did not find clear evidence of surplus killing behavior in brown bears foraging on salmon, but prey selectivity manifested itself through both discarding and partial consumption, which contributes to our ability to predict transport of salmon nutrients by bears across ecosystem boundaries.

opencc-zeroDec 2018View details →

Data from: Incidence of multiple paternity and inbreeding in high-density brown bear populations on the Shiretoko Peninsula, Hokkaido, Japan

Understanding the breeding ecology of a species is essential for the appropriate conservation and management of wildlife. In brown bears, females occasionally copulate with multiple males in one breeding season, which may lead to multiple paternity in a single litter. In contrast, inbreeding, a potential factor in the reduction of genetic diversity, may occur, particularly in threatened populations. However, few studies have reported the frequency of these phenomena in brown bear populations. Here, we investigated the incidence of multiple paternity and inbreeding in a high-density brown bear population on the Shiretoko Peninsula in Hokkaido, Japan. A total of 837 individuals collected from 1998 to 2017 were genotyped at 21 microsatellite loci, and parentage analysis was performed. Out of 70–82 litters with ≥2 offspring, 14.6–17.1% of litters were sired by multiple males. This was comparable to the rate reported in a Scandinavian population, although population density and litter size, factors that potentially affect the incidence of multiple paternity, differed between the two populations. Out of 222 mother-father mating pairs, six litters (2.7%) resulted from matings between fathers and daughters. Additionally, one (0.5%) and four (1.8%) cases of mating between maternal half-siblings and between paternal half-siblings, respectively, were observed; however, no cases of mating between mothers and sons or between full-siblings were observed. Our results suggest that male-biased natal dispersal effectively limits mating between closely related individuals (aside from fathers and daughters) in brown bears.

opencc-zeroDec 2015View details →

Data from: Hunting promotes sexual conflict in brown bears

The removal of individuals through hunting can destabilize social structure, potentially affecting population dynamics. Although previous studies have shown that hunting can indirectly reduce juvenile survival through increased sexually selected infanticide (SSI), very little is known about the spatiotemporal effects of male hunting on juvenile survival. Using detailed individual monitoring of a hunted population of brown bears (Ursus arctos) in Sweden (1991–2011), we assessed the spatiotemporal effect of male removal on cub survival. We modelled cub survival before, during and after the mating season. We used three proxies to evaluate spatial and temporal variation in male turnover; distance and timing of the closest male killed and number of males that died around a female's home range centre. Male removal decreased cub survival only during the mating season, as expected in seasonal breeders with SSI. Cub survival increased with distance to the closest male killed within the previous 1·5 years, and it was lower when the closest male killed was removed 1·5 instead of 0·5 year earlier. We did not detect an effect of the number of males killed. Our results support the hypothesis that social restructuring due to hunting can reduce recruitment and suggest that the distribution of the male deaths might be more important than the overall number of males that die. As the removal of individuals through hunting is typically not homogenously distributed across the landscape, spatial heterogeneity in hunting pressure may cause source–sink dynamics, with lower recruitment in areas of high human-induced mortality.

opencc-zeroDec 2014View details →

Data from: Consequences of a demographic bottleneck on genetic structure and variation in the Scandinavian brown bear

The Scandinavian brown bear went through a major decline in population size approximately 100 years ago, due to intense hunting. After being protected, the population subsequently recovered and today numbers in the thousands. The genetic diversity in the contemporary population has been investigated in considerable detail, and it has been shown that the population consists of several subpopulations that display relatively high levels of genetic variation. However, previous studies have been unable to resolve the degree to which the demographic bottleneck impacted the contemporary genetic structure and diversity. In this study, we used mitochondrial and microsatellite DNA markers from pre- and postbottleneck Scandinavian brown bear samples to investigate the effect of the bottleneck. Simulation and multivariate analysis suggested the same genetic structure for the historical and modern samples, which are clustered into three subpopulations in southern, central and northern Scandinavia. However, the southern subpopulation appears to have gone through a marked change in allele frequencies. When comparing the mitochondrial DNA diversity in the whole population, we found a major decline in haplotype numbers across the bottleneck. However, the loss of autosomal genetic diversity was less pronounced, although a significant decline in allelic richness was observed in the southern subpopulation. Approximate Bayesian computations provided clear support for a decline in effective population size during the bottleneck, in both the southern and northern subpopulations. These results have implications for the future management of the Scandinavian brown bear because they indicate a recent loss in genetic diversity and also that the current genetic structure may have been caused by historical ecological processes rather than recent anthropogenic persecution.

opencc-zeroDec 2011View details →

Data from: Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus)

Polar bears (Ursus maritimus) and brown bears (Ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic genetic comparisons have been made. We used previously-published genotype data for 8 microsatellite DNA loci from 930 brown bears in 19 populations and 473 polar bears in 16 populations to compare the population genetic relationships of extant populations of the species. Genetic distances (Nei standard distance = 1.157), the proportion of private alleles (52% of alleles are not shared by the species), and Bayesian cluster analysis are consistent with morphological and life history characteristics that distinguish polar bears and brown bears as different species with little or no gene flow among extant populations.

opencc-zeroFeb 2022View details →

Brown bear population vital rates

Identifying mechanisms of population change is fundamental for conserving small and declining populations and determining effective management strategies. Few studies, however, have measured the demographic components of population change for small populations of mammals (< 50 individuals). We estimated vital rates and trends in two adjacent but genetically distinct, threatened brown bear (Ursus arctos) populations in British Columbia, Canada, following the cessation of hunting. One population had approximately 45 resident bears but had some genetic and geographic connectivity to neighbouring populations, while the other population had < 25 individuals and was isolated. We estimated population-specific vital rates by monitoring survival and reproduction of telemetered female bears and their dependent offspring from 2005 to 2018. In the larger, connected population, independent female survival was 1.00 (95% CI: 0.96-1.00) and the survival of cubs in their first year was 0.85 (95% CI: 0.62-0.95). In the smaller, isolated population, independent female survival was 0.81 (95% CI: 0.64-0.93) and first-year cub survival was 0.33 (95% CI: 0.11-0.67). Reproductive rates did not differ between populations. The large differences in age-specific survival estimates resulted in a projected population increase in the larger population (λ = 1.09; 95% CI: 1.04-1.13) and population decrease in the smaller population (λ = 0.84; 95% CI: 0.72-0.95). Low female survival in the smaller population was the result of both continued human-caused mortality and an unusually high rate of natural mortality. Low cub survival may have been due to inbreeding and the loss of genetic diversity common in small populations, or to limited resources. In a systematic literature review, we compared our population trend estimates with those reported for other small populations (< 300 individuals) of brown bears. Results suggest that once brown bear populations become small and isolated, populations rarely increase and, even with intensive management, recovery remains challenging.

opennotspecifiedJun 2015View details →

Distribution. Obi, Bisa, and Obilatu (= Obi-Latoe) Is in the NC Moluccas, Indonesia. Descriptiveor notes. Head-body 36-39 cm, tail 30-33.5 cm; weight 1.1-1.4 kg. The Obi Cuscus is a relatively small cuscus (condylobasal length 65-69 mm). Skull of the Obi Cuscus is similar to that of the Moluccan Cuscus (P. ornatus) and the Gebe Cuscus (P. alexandrae), and it bears a prominent diastema between incisor and canine but is smaller than those species and has smaller teeth. The Obi Cuscus has two color morphs: orange-brown or gray dorsal fur with dark underfur. Ventral fur is white to yellow. Dark dorsal stripe extends from head to mid-back or rump. in Phalangeridae

Distribution. Obi, Bisa, and Obilatu (= Obi-Latoe) Is in the NC Moluccas, Indonesia. Descriptiveor notes. Head-body 36-39 cm, tail 30-33.5 cm; weight 1.1-1.4 kg. The Obi Cuscus is a relatively small cuscus (condylobasal length 65-69 mm). Skull of the Obi Cuscus is similar to that of the Moluccan Cuscus (P. ornatus) and the Gebe Cuscus (P. alexandrae), and it bears a prominent diastema between incisor and canine but is smaller than those species and has smaller teeth. The Obi Cuscus has two color morphs: orange-brown or gray dorsal fur with dark underfur. Ventral fur is white to yellow. Dark dorsal stripe extends from head to mid-back or rump.

opencc-zeroDec 2011View details →

Data from: Using a reference population yardstick to calibrate and compare genetic diversity reported in different studies: an example from the brown bear.

In species with large geographic ranges, genetic diversity of different populations may be well studied, but differences in loci and sample sizes can make the results of different studies difficult to compare. Yet, such comparisons are important for assessing the status of populations of conservation concern. We propose a simple approach of using a single well-studied reference population as a "yardstick" to calibrate results of different studies to the same scale, enabling comparisons. We use a well-studied large carnivore, the brown bear (Ursus arctos), as a case study to demonstrate the approach. As a reference population, we genotyped 513 brown bears from Slovenia using 20 polymorphic microsatellite loci. We used this dataset to calibrate and compare heterozygosity and allelic richness for 30 brown bear populations from 10 different studies across the global distribution of the species. The simplicity of the reference population approach makes it useful for other species, enabling comparisons of genetic diversity estimates between previously incompatible studies and improving our understanding of how genetic diversity is distributed along a species range.

opencc-by-4.0Dec 2021View details →

Supplementary Information - Circulating insulin-like growth factor system adaptations in hibernating brown bears indicate increased tissue IGF availability

Supplementary figures and tables for the manuscript entitled “Circulating insulin-like growth factor system adaptations in hibernating brown bears indicate increased tissue IGF availability”.

opencc-zeroSep 2022View details →

Results of survey for selected parasites in Alaska brown bears (Ursus arctos)

To assess the prevalence of endo- and ectoparasites in Alaska brown bears (Ursus arctos), blood and fecal samples were collected during 2013 – 2016 from five locations: Gates of the Arctic National Park and Preserve (GAAR), Katmai National Park (KATM), Lake Clark National Park and Preserve (LACL), Yakutat Forelands (YAK), and Kodiak Island (KOD). Standard fecal centrifugal-flotation was used to screen for gastrointestinal parasites, molecular techniques were used to test blood for the presence of Bartonella and Babesia spp., and an enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to Sarcoptes scabiei, a species of mite recently associated with mange in American black bears (Ursus americanus). From fecal flotations (n=160), we identified the following helminths: Uncinaria sp. (n=16, 10.0%), Baylisascaris sp. (n=5, 3.1%), Dibothriocephalus sp. (n=2, 1.2%), and taeniid-type eggs (n=1, 0.6%). Molecular screening for intraerythrocytic parasites (Babesia spp.) and intracellular bacteria (Bartonella spp.) was negative for all bears tested. We detected antibodies to S. scabiei in six out of 59 (10.2%) individuals. The data set contains 238 rows, each row representing a capture/sampling event for an individual bear. The location of the bear, month and year of sampling, and bear demographic information (ID number, sex, and age) are provided for each entry, as well as as which of the three tests (fecal flotation, Bartonella/Babesia PCR, Sarcoptes ELISA) were performed on samples collected during that capture event. Results are provided for each test when it was performed. For fecal flotation, there are columns for presence of the four detected parasite genera (1= present, 0 = absent), as well as a column for other fecal findings. For Bartonella/Babesia testing, a positive or negative result is provided when the tests were performed. For the Sarcoptes ELISA, results are provided based on bear positive controls and dog positive controls. Samples were reported as positive when they were positive when run with both positive controls.

opennotspecifiedAug 2015View details →

Figure 2 in Exceptional maternal lineage diversity in brown bears (Ursus arctos) from Turkey

Figure 2. Median-joining network. Median-joining network showing the evolutionary relationships and probable ancestral connections among haplotypes from the Western Palaearctic based on the 269-bp sequence of mtDNA control region. Lengths of the lines connecting different haplotype groups are proportional to the number of mutational positions. The size of each circle is proportional to the number of individuals carrying that particular haplotype (see Table 1). The proportion of haplotypes from Turkey is framed with bold lines, i.e. a circle fully enclosed by a bold line represents Turkishonly haplotypes.

opennotspecifiedAug 2015View details →

Figure 3 in Exceptional maternal lineage diversity in brown bears (Ursus arctos) from Turkey

Figure 3. Map of the region with sample localities and clade designation (only specimens with known origins are shown; clade 1, tones of blue; clade 3, tones of red; clade 7, tones of green).