Population genetics of the white-phased "Spirit" black bear of British Columbia

The Spirit (or Kermode) bear is a white-phased black bear found on the northwest coast of British Columbia, and is one of the most striking color polymorphisms found in mammals. A single nucleotide polymorphism at the melanocortin 1 receptor gene (mc1r) locus is the cause of this recessive w variant. Recently, evidence suggests that the white color provides a selective advantage during salmon hunting. Here we examine the effects of favorable selection, gene flow, genetic drift, and positive-assortative mating in an effort to understand the establishment and maintenance of this polymorphism and the observed heterozygote deficiency for mc1r but not for microsatellite loci. It appears that genetic drift was important in the establishment of the w allele and that the selective advantage was important to counteract immigration from populations without the w allele. Positive-assortative mating can result in a deficiency of heterozygotes but needs to be quite high to result in the large deficiency of heterozygotes observed, suggesting that other factors must also be contributing. Examination of population genetic factors, singly and jointly, provides insight into the establishment and maintenance of this unusual polymorphism.     

Genetic diversity and differentiation of Kermode bear populations

The Kermode bear is a white phase of the North American black bear that occurs in low to moderate frequency on British Columbia's mid-coast. To investigate the genetic uniqueness of populations containing the white phase, and to ascertain levels of gene flow among populations, we surveyed 10 highly polymorphic microsatellite loci, assayed from trapped bear hairs. A total of 216 unique bear genotypes, 18 of which were white, was sampled among 12 localities. Island populations, where Kermodes are most frequent, show approximately 4% less diversity than mainland populations, and the island richest in white bears (Gribbell) exhibited substantial genetic isolation, with a mean pairwise FST of 0.14 with other localities. Among all localities, FST for the molecular variant underlying the coat-colour difference (A893G) was 0.223, which falls into the 95th percentile of the distribution of FST values among microsatellite alleles, suggestive of greater differentiation for coat colour than expected under neutrality. Control-region sequences confirm that Kermode bears are part of a coastal or western lineage of black bears whose existence predates the Wisconsin glaciation, but microsatellite variation gave no evidence of past population expansion. We conclude that Kermodism was established and is maintained in populations by a combination of genetic isolation and somewhat reduced population sizes in insular habitat, with the possible contribution of selective pressure and/or nonrandom mating.     

Adaptive coat colour polymorphism in the Kermode bear of coastal British Columbia

We investigated potential ecological attributes of the striking coat colour polymorphism in the black bear ( Ursus americanus kermodei Hornaday) occurring on several small islands off the mid-coast of British Columbia, where a white morph (Kermode), fully recessive to the black morph, reaches 10–25% of the population. During three autumn field seasons (2000–2002; 697 h of observation time), we monitored salmon capture behaviour of individual bears (black, N  = 37; white, N  = 4). Both colour morphs foraged on salmon throughout daylight and darkness but with twice the rate during darkness. Log-linear analysis of capture efficiency (success/attempts) and average capture success per bout of the white morph was marginally lower than the black morph during darkness (22.8%, N  = 158 versus 25.8%, N  = 279 respectively; P  < 0.04), although it was significantly higher during daylight (34.1%, N  = 132 versus 25.3%, N  = 896, respectively, P  < 0.02), with similar trends in three different pursuit modes. Replicated ( N  = 10–14) field experiments involving a colour dimorphic simulated predator (i.e. human in a black or white cloak) showed that salmon were one-half as evasive during darkness than during daylight, with no differences ( P  > 0.4) in response to either the white or black models; however, during daylight, salmon were twice as evasive to the black compared to the white model ( P  < 0.001). The persistence of this coat colour polymorphism may be facilitated by increased salmon accessibility to the Kermode bear and diel foraging differences between morphs. These results are consistent with multi-niche models of adaptive variability.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 479–488.     

Sequence analysis of three pigmentation genes in the Newfoundland population of Canis latrans links the Golden Retriever Mc1r variant to white coat color in coyotes

Three genes, Mc1r, Agouti, and CBD103, interact in a type-switching process that controls much of the pigmentation variation observed in mammals. A deletion in the CBD103 gene is responsible for dominant black color in dogs, while the white-phased black bear (“spirit bear”) of British Columbia, Canada, is the lightest documented color variant caused by a mutation in Mc1r. Rare all-white animals have recently been discovered in a new northeastern population of the coyote in insular Newfoundland and Labrador, Canada. To investigate the causative gene and mutation of white coat in coyotes, we sequenced the three type-switching genes in white and dark-phased animals from Newfoundland. The only sequence variants unambiguously associated with white color were in Mc1r, and one of these variants causes the amino acid variant R306Ter, a premature stop codon also linked to coat color in Golden Retrievers and other dogs with yellow/red coats. The allele carrying R306Ter in coyotes matches that in the Golden Retriever at other variable amino acid sites and hence may have originated in these dogs. Coyotes experienced introgression with wolves and dogs as they colonized northeastern North America, and coyote/Golden Retriever interactions have been observed in Newfoundland. We speculate that natural selection, with or without a founder effect, may contribute to the observed frequency of white coyotes in Newfoundland, as it has contributed to the high frequency of white bears, and of a domestic dog-derived CBD allele in gray wolves.     

Unraveling the mystery of the glacier bear: Genetic population structure of black bears (Ursus americanus) within the range of a rare pelage type

Glacier bears are a rare grey color morph of American black bear (Ursus americanus) found only in northern Southeast Alaska and a small portion of western Canada. We examine contemporary genetic population structure of black bears within the geographic extent of glacier bears and explore how this structure relates to pelage color and landscape features of a recently glaciated and highly fragmented landscape. We used existing radiocollar data to quantify black bear home‐range size within the geographic range of glacier bears. The mean home‐range size of female black bears in the study area was 13 km² (n = 11), whereas the home range of a single male was 86.9 km². We genotyped 284 bears using 21 microsatellites extracted from noninvasively collected hair as well as tissue samples from harvested bears. We found ten populations of black bears in the study area, including several new populations not previously identified, divided largely by geographic features such as glaciers and marine fjords. Glacier bears were assigned to four populations found on the north and east side of Lynn Canal and the north and west side of Glacier Bay with a curious absence in the nonglaciated peninsula between. Lack of genetic relatedness and geographic continuity between black bear populations containing glacier bears suggest a possible unsampled population or an association with ice fields. Further investigation is needed to determine the genetic basis and the adaptive and evolutionary significance of the glacier bear color morph to help focus black bear conservation management to maximize and preserve genetic diversity.     

Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction.     

Influence of Campsites on Black Bear Habitat Use and Potential Impact on Caribou Restoration

Ursus americanus(black bear) predation could limit the success of the proposed restoration of Rangifer tarandus (woodland caribou) to Minnesota. The problem was recently identified as a major factor in the failure of a similar restoration effort in Maine. During the summer of 1991 we conducted a survey in the region of the proposed restoration, using bait stations to identify bear presence. Four settings were sampled: islands with campsites, islands without campsites, mainland areas with campsites, and mainland areas without campsites. Results from the survey suggest that black bears use areas with campsites more than those without. Whereas caribou may use islands preferentially for calving to escape predation, islands with campsites may be unfavorable for caribou calf survival due to frequent bear visitation.     

Excision of transposable elements from the chalcone isomerase and dihydroflavonol 4-reductase genes may contribute to the variegation of the yellow-flowered carnation (Dianthus caryophyllus)

In the "Rhapsody" cultivar of the carnation, which bears white flowers variegated with red flecks and sectors, a transposable element, dTdic1, belonging to the Ac/Ds superfamily, was found within the dihydroflavonol 4-reductase (DFR) gene. The red flecks and sectors of "Rhapsody" may be attributable to a reversion to DFR activity after the excision of dTdic1. The yellow color of the carnation petals is attributed to the synthesis and accumulation of chalcone 2'-glucoside. In several of the carnation cultivars that bear yellow flowers variegated with white flecks and sectors, both the chalcone isomerase (CHI) and DFR genes are disrupted by dTdic1.     

Morbillivirus and <Emphasis Type="Italic">Toxoplasma</Emphasis> Exposure and Association with Hematological Parameters for Southern Beaufort Sea Polar Bears: Potential Response to Infectious Agents in a Sentinel Species

Arctic temperatures are increasing in response to greenhouse gas forcing and polar bears have already responded to changing conditions. Declines in body stature and vital rates have been linked to warming-induced loss of sea-ice. As food webs change and human activities respond to a milder Arctic, exposure of polar bears and other arctic marine organisms to infectious agents may increase. Because of the polar bear’s status as arctic ecosystem sentinel, polar bear health could provide an index of changing pathogen occurrence throughout the Arctic, however, exposure and monitoring protocols have yet to be established. We examine prevalence of antibodies to Toxoplasma gondii, and four morbilliviruses (canine distemper [CDV], phocine distemper [PDV], dolphin morbillivirus [DMV], porpoise morbillivirus [PMV]) including risk factors for exposure. We also examine the relationships between antibody levels and hematologic values established in the previous companion article. Antibodies to Toxoplasma gondii and morbilliviruses were found in both sample years. We found a significant inverse relationship between CDV titer and total leukocytes, neutrophils, monocytes, and eosinophils, and a significant positive relationship between eosinophils and Toxoplasma gondii antibodies. Morbilliviral prevalence varied significantly among age cohorts, with 1–2 year olds least likely to be seropositive and bears aged 5–7 most likely. Data suggest that the presence of CDV and Toxoplasma gondii antibodies is associated with polar bear hematologic values. We conclude that exposure to CDV-like antigen is not randomly distributed among age classes and suggest that differing behaviors among life history stages may drive probability of specific antibody presence.     

Phylogeographic and Demographic Analysis of the Asian Black Bear (Ursus thibetanus) Based on Mitochondrial DNA

The Asian black bear Ursus thibetanus is widely distributed in Asia and is adapted to broad-leaved deciduous forests, playing an important ecological role in the natural environment. Several subspecies of U. thibetanus have been recognized, one of which, the Japanese black bear, is distributed in the Japanese archipelago. Recent molecular phylogeographic studies clarified that this subspecies is genetically distantly related to continental subspecies, suggesting an earlier origin. However, the evolutionary relationship between the Japanese and continental subspecies remained unclear. To understand the evolution of the Asian black bear in relation to geological events such as climatic and transgression-regression cycles, a reliable time estimation is also essential. To address these issues, we determined and analyzed the mt-genome of the Japanese subspecies. This indicates that the Japanese subspecies initially diverged from other Asian black bears in around 1.46Ma. The Northern continental population (northeast China, Russia, Korean peninsula) subsequently evolved, relatively recently, from the Southern continental population (southern China and Southeast Asia). While the Japanese black bear has an early origin, the tMRCAs and the dynamics of population sizes suggest that it dispersed relatively recently in the main Japanese islands: during the late Middle and Late Pleistocene, probably during or soon after the extinction of the brown bear in Honshu in the same period. Our estimation that the population size of the Japanese subspecies increased rapidly during the Late Pleistocene is the first evidential signal of a niche exchange between brown bears and black bears in the Japanese main islands.This interpretation seems plausible but was not corroborated by paleontological evidence that fossil record of the Japanese subspecies limited after the Late Pleistocene. We also report here a new fossil record of the oldest Japanese black bear from the Middle Pleistocene, and it supports our new evolutionary hypothesis of the Japanese black bear.     

Dietary adjustability of grizzly bears and American black bears in Yellowstone National Park

Grizzly bears (Ursus arctos) and American black bears (U. americanus) are sympatric in much of Yellowstone National Park. Three primary bear foods, cutthroat trout (Oncorhynchus clarki), whitebark pine (Pinus albicaulis) nuts, and elk (Cervus elaphus), have declined in recent years. Because park managers and the public are concerned about the impact created by reductions in these foods, we quantified bear diets to determine how bears living near Yellowstone Lake are adjusting. We estimated diets using: 1) stable isotope and mercury analyses of hair samples collected from captured bears and from hair collection sites established along cutthroat trout spawning streams and 2) visits to recent locations occupied by bears wearing Global Positioning System collars to identify signs of feeding behavior and to collect scats for macroscopic identification of residues. Approximately 45 ± 22% ( ± SD) of the assimilated nitrogen consumed by male grizzly bears, 38 ± 20% by female grizzly bears, and 23 ± 7% by male and female black bears came from animal matter. These assimilated dietary proportions for female grizzly bears were the same as 10 years earlier in the Lake area and 30 years earlier in the Greater Yellowstone Ecosystem. However, the proportion of meat in the assimilated diet of male grizzly bears decreased over both time frames. The estimated biomass of cutthroat trout consumed by grizzly bears and black bears declined 70% and 95%, respectively, in the decade between 1997–2000 and 2007–2009. Grizzly bears killed an elk calf every 4.3 ± 2.7 days and black bears every 8.0 ± 4.0 days during June. Elk accounted for 84% of all ungulates consumed by both bear species. Whitebark pine nuts continue to be a primary food source for both grizzly bears and black bears when abundant, but are replaced by false-truffles (Rhizopogon spp.) in the diets of female grizzly bears and black bears when nut crops are minimal. Thus, both grizzly bears and black bears continue to adjust to changing resources, with larger grizzly bears continuing to occupy a more carnivorous niche than the smaller, more herbivorous black bear. © 2012 The Wildlife Society.     

Contrasting Activity Patterns of Sympatric and Allopatric Black and Grizzly Bears

ABSTRACT The distribution of grizzly (Ursus arctos) and American black bears (U. americanus) overlaps in western North America. Few studies have detailed activity patterns where the species are sympatric and no studies contrasted patterns where populations are both sympatric and allopatric. We contrasted activity patterns for sympatric black and grizzly bears and for black bears allopatric to grizzly bears, how human influences altered patterns, and rates of grizzly-black bear predation. Activity patterns differed between black bear populations, with those sympatric to grizzly bears more day-active. Activity patterns of black bears allopatric with grizzly bears were similar to those of female grizzly bears; both were crepuscular and day-active. Male grizzly bears were crepuscular and night-active. Both species were more night-active and less day-active when ≤1 km from roads or developments. In our sympatric study area, 2 of 4 black bear mortalities were due to grizzly bear predation. Our results suggested patterns of activity that allowed for intra- and inter-species avoidance. National park management often results in convergence of locally high human densities in quality bear habitat. Our data provide additional understanding into how bears alter their activity patterns in response to other bears and humans and should help park managers minimize undesirable bear-human encounters when considering needs for temporal and spatial management of humans and human developments in bear habitats.     

Genetic status of Asiatic black bear (Ursus thibetanus) reintroduced into South Korea based on mitochondrial DNA and microsatellite loci analysis

The Asiatic black bear is one of the most endangered mammals in South Korea owing to population declines resulting from human exploitation and habitat fragmentation. To restore the black bear population in South Korea, 27 bear cubs from North Korea and Russian Far East (Primorsky Krai) were imported and released into Jirisan National Park, a reservoir of the largest wild population in South Korea, in 2004. To monitor the success of this reintroduction, the genetic diversity and population structure of the reintroduced black bears were measured using both mitochondrial and nuclear DNA markers. Mitochondrial D-loop region DNA sequences (615 bp) of 43 Japanese black bears from previous study and 14 Southeast Asian black bears in this study were employed to obtain phylogenetic inference of the reintroduced black bears. The mitochondrial phylogeny indicated Asiatic black bear populations from Russian Far East and North Korea form a single evolutionary unit distinct from populations from Japan and Southeast Asia. Mean expected heterozygosity (H(E)) across 16 microsatellite loci was 0.648 for Russian and 0.676 for North Korean populations. There was a moderate but significant level of microsatellite differentiation (F(ST) = 0.063) between black bears from the 2 source areas. In addition, genetic evidences revealed that 2 populations are represented as diverging groups, with lingering genetic admixture among individuals of 2 source populations. Relatedness analysis based on genetic markers indicated several discrepancies with the pedigree records. Implication of the phylogenetic and genetic evidences on long-term management of Asiatic black bears in South Korea is discussed.     

TYRP1 and MC1R genotypes and their effects on coat color in dogs

We used PCR amplification of cDNA prepared from skin biopsies to determine the nearly full-length, protein-coding sequence of dog TYRP1, and to define sequence variants potentially responsible for the B locus. One common variant contained a premature stop codon in exon 5 (Q331ter), and the other deleted a proline residue in exon 5 (345delP). A third variant in exon 2 (S41C) occurred less frequently. We genotyped 43 brown (including brown and white) and 34 black (including tricolor, black-and-tan, and black and white) dogs. All 43 of the brown group carried two or more of these sequence variants likely to interfere with TYRP1 function, whereas 0 of 34 in the black group carried two or more of these variants (10 carried one variant). We also genotyped 13 black-nosed and 10 brown-nosed dogs whose coat color was described as red, yellow, gold, apricot, or orange (including various degrees of white). All these dogs were homozygous for a R306X MC1R variant shown to be associated with these coat color phenotypes. The black or brown nose correlated perfectly with the absence or presence of the same three TYRP1 variants described above. TYRP1 was linkage mapped to dog chromosome 11, with a SNP in exon 7.     

陕西汉中地区黑熊的现状,分布及保护措施

１９９１－１９９３年,作者在陕西省汉中林区采用三阶抽样设计调查并询访群众,求算每个所选择的最小样本单位（三级区）的方差,推算黑熊整体数量。根据黑熊数量将该地林区划分为３个密度区级：高密度区（０．０３头／ｋｍ￣２以上）,秦岭中山区;中密度区（０．０１－０．０２９头／ｋｍ￣２）,巴山中山区;低密度区（０．０１头／ｋｍ￣２以下）,秦巴低山丘陵区。全区有黑熊３１２头,平均密度０．０３５／ｋｍ￣２,遍布１０县１６６个乡。分析了各地黑熊数量多寡的原因,提出了相应的保护措施。     

Prevalence of Trichinella T9 in Japanese black bears (Ursus thibetanus japonicus) in Iwate prefecture,Japan

Trichinellosis is a meat-borne zoonotic disease caused by nine Trichinella speices and three unclassified genotypes. In Japan, four domestic outbreaks of human trichinellosis are reported sporadically and were associated with the consumption of wild bear meat. This study examined Trichinella prevalence and its species in black bears, Ursus thibetanus japonicus in Iwate prefecture, Japan. Trichinella T9 larvae identified molecularly were first detected in 1.4% (2/144) of the masseters of black bears examined, and their densities were low (1 and 0.3 larvae /g muscle, respectively). Two cytochrome C oxidase I (COI) haplotypes (sequences) of Trichinella T9 were found in distinct bear populations, suggesting that Trichinella T9 populations isolated genetically by bear populations would occur in Japan.     

Longevity and reuse of black bear dens in managed forests of coastal British Columbia

We evaluated longevity and reuse of denning structures by American black bears (Ursus americanus) in coastal temperate rainforests of British Columbia from 1992 to 2010 to assess potential impacts of forest management on these critical habitat features over time. We identified 67 dens during a 4-yr intensive radio-telemetry study (1992–1995): 40 dens of 21 radio-collared black bears and 27 dens found incidentally. Dens occurred in or beneath large diameter trees or wooden structures derived from trees (i.e., logs, root boles, and stumps; = 143 cm diameter, SD = 49 cm). Longevity of dens varied by type, tree species that formed the den, and forest management that occurred at or near the den. Twenty-four of 28 dens of radio-collared bears that were monitored were still usable in 2010, whereas only 5 of 14 dens found incidentally were still usable in 2010. We assessed reuse of bear dens 3 times following initial identification: during the radio-telemetry study, again in 2000, and finally in 2010. Radio-collared bears reused dens from previous years on 7 of 25 potential occasions during the course of the radio-telemetry study. Upon assessment in 2000 and 2010, 17 of 24 (71%) available dens first used by radio-collared bears were reused at least once between 1993 and 2010. The high rate of reuse may indicate low availability of den structures in our study area. Because black bears in coastal British Columbia only used trees or structures derived from trees for winter dens and forest harvesting reduces the supply of these necessary structures, conservation and recruitment of suitable den trees is necessary if maintaining black bear populations is a management goal in these areas. © 2011 The Wildlife Society.     

黑熊种群年龄结构和生命表初探

本文以四川野生黑熊（Ｓｅｌｅｎａｒｃｔｏｓ ｔｈｉｂｅｔａｎｕｓ）的头骨标本为基础材料,结合养熊场所积累的有关黑熊的年龄构成、繁殖、死亡等资料,运用数学分析方法对四川黑熊种群的年龄儿性比进行了分析研究,编制出黑熊的静态生命表,分析了黑熊种群的内禀增长能力,并得出了野生黑熊种群的平均期望寿命为６．３６６岁,净生殖率（Ｒｏ）为１．６９３２５,平均世代时间（Ｔ）为１１．５４４年,内禀增长率（ｒｍ）为０．     

Fatal attacks by American black bear on people: 1900–2009

At least 63 people were killed in 59 incidents by non-captive black bear (Ursus americanus) during 1900–2009. Fatal black bear attacks occurred in Canada and Alaska (n = 49) and in the lower 48 states (n = 14). There were 3.5 times as many fatal attacks in Canada and Alaska but only 1.75 times as many black bears, and much less human contact for black bears in Canada and Alaska. There was a weak positive correlation (r_s = 0.56, P ≤ 0.000) between the estimated size of a bear population within a given jurisdiction and the number of fatal black bear attacks. Some jurisdictions had no fatal black bear attacks but had large estimated black bear populations. Of fatal attacks, 86% (54 of 63, 1.08/yr) occurred between 1960 and 2009. There was positive linear relationship between the number of fatal black bear attacks per decade and human population size in the United States and Canada per decade (r² = 0.92, β = 0.000, P ≤ 0.001). Of fatal attacks, 91% (49 of 54) occurred on parties of 1 or 2 persons. In 38% (15 of 40) of incidents, peoples' food or garbage probably influenced the bear being in the attack location. We judged that the bear involved acted as a predator in 88% (49 of 56) of fatal incidents. Adult (n = 23) or subadult (n = 10) male bears were involved in 92% (33 of 36) of fatal predatory incidents, reflecting biological and behavioral differences between male and female bears. That most fatal black bear attacks were predatory and were carried out by 1 bear shows that females with young are not the most dangerous black bears. As a result of our research agencies managing black bear can more accurately understand the risk of being killed by a black bear, and can communicate this to the public. With training, people can learn to recognize the behaviors of a bear considering them as prey and can act to deter predation. © 2011 The Wildlife Society.     

Prevalence of Trichinella spp. in black bears, grizzly bears, and wolves in the Dehcho Region, Northwest Territories, Canada, including the first report of T. nativa in a grizzly bear from Canada

Samples of muscle from 120 black bears (Ursus americanus), 11 grizzly bears (Ursus arctos), and 27 wolves (Canis lupus) collected in the Dehcho Region of the Northwest Territories from 2001 to 2010 were examined for the presence of Trichinella spp. larvae using a pepsin-HCl digestion assay. Trichinella spp. larvae were found in eight of 11 (73%) grizzly bears, 14 of 27 (52%) wolves, and seven of 120 (5.8%) black bears. The average age of positive grizzly bears, black bears, and wolves was 13.5, 9.9, and approximately 4 yr, respectively. Larvae from 11 wolves, six black bears, and seven grizzly bears were genotyped. Six wolves were infected with T. nativa and five with Trichinella T6, four black bears were infected with T. nativa and two with Trichinella T6, and all seven grizzly bears were infected with Trichinella T6 and one of them had a coinfection with T. nativa. This is the first report of T. nativa in a grizzly bear from Canada. Bears have been linked to trichinellosis outbreaks in humans in Canada, and black bears are a subsistence food source for residents of the Dehcho region. In order to assess food safety risk it is important to monitor the prevalence of Trichinella spp. in both species of bear and their cohabiting mammalian food sources.