Incidence of Multiple Paternity and Inbreeding in High-Density Brown Bear Populations on the Shiretoko Peninsula, Hokkaido, Japan

Shimozuru, Michito; Shirane, Yuri; Tsuruga, Hifumi; Yamanaka, Masami; Nakanishi, Masanao; Ishinazaka, Tsuyoshi; Kasai, Shinsuke; Nose, Takane; Masuda, Yasushi; Fujimoto, Yasushi; Mano, Tsutomu; Tsubota, Toshio

doi:10.1093/jhered/esz002

Cited by 45 publications

(19 citation statements)

References 77 publications

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“…The mating system of the brown bear is generally classified as polygamous [8]. One to three cubs are born per litter and multiple paternity in litters has been documented by genetic studies in wild bears [7,21]. The present study confirmed that two to three follicles ovulate spontaneously within four to seven days after GnRH treatment.…”

Section: Discussionsupporting

confidence: 82%

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Monitoring follicular dynamics to determine estrus type and timing of ovulation induction in captive brown bears (<i>Ursus arctos</i>)

Torii

Matsumoto²,

Sakamoto³

et al. 2020

Journal of Reproduction and Development

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It is important to understand ovarian physiology when developing an artificial insemination (AI) protocol. Brown bears (Ursus arctos) have a breeding season from May to July, although the type of estrus (polyestrus or monoestrus) is still contested. The present study aimed to define the ovarian dynamics, including follicular waves and ovulatory follicle size, and estrus type in brown bears. Six brown bears were used for ovarian ultrasonography; four were observed between April and October (before the start and after the end of the breeding season) and two in June (breeding season). In addition, we attempted to induce ovulation by administering a gonadotropin releasing hormone (GnRH) agonist. We observed follicular development in April in four bears, but follicles did not develop to greater than 6.0 mm in diameter until May. Thereafter, a group of follicles developed to more than 6.0 mm and grew as dominant follicles, except in one bear. After ovulation and subsequent corpus luteum (CL) formation, the follicular waves disappeared. Furthermore, in three bears treated with GnRH, follicles between 8.2 to 11.2 mm in diameter at the time of treatment ovulated and formed CLs. In two bears, follicles between 5.8 to 8.8 mm ovulated spontaneously within the observation interval. Our results suggest that brown bears may be monoestrous animals. Therefore, AI can only be performed once during the breeding season. Our results also suggest that dominant follicles larger than 8.0 mm are a suitable size for inducing ovulation.

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Section: Discussionsupporting

confidence: 82%

“…A few studies have suggested that brown bears are polyestrous animals because of multiple distinct estrous observations and multiple paternities [7,21]. In captive observations, Some females mate continuously for more than two weeks and the others mate for up to 20 days with 3-20 days interval [15].…”

Section: Discussionmentioning

confidence: 99%

Monitoring follicular dynamics to determine estrus type and timing of ovulation induction in captive brown bears (<i>Ursus arctos</i>)

Torii

Matsumoto²,

Sakamoto³

et al. 2020

Journal of Reproduction and Development

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“…However, it may limit the turnover of reproductive males and allow a limited number of males to dominate reproductive opportunities, which would increase the occurrence of inbreeding and have a negative impact on genetic diversity 49 . Although inbreeding was not www.nature.com/scientificreports/ prominent in this population 33 , continued genetic monitoring is important. Second, even in the remote, special protection area of the national park (i.e., Rusha area), maternal human habituation enhances the likelihood of human-bear conflict.…”

Section: Resultsmentioning

confidence: 94%

“…S1 ). Group 3 comprised 13 very highly habituated bears that had been visually identified and frequently observed in this area from the late 1990s to 2018 28 , 31 – 33 . Among them, six bears were captured and released with ear tags for radiotracking between 2013 and 2018 31 .…”

Section: Methodsmentioning

confidence: 99%

Maternal human habituation enhances sons’ risk of human-caused mortality in a large carnivore, brown bears

Shimozuru

Shirane

Yamanaka

et al. 2020

Sci Rep

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Human habituation of large carnivores is becoming a serious problem that generates human–wildlife conflict, which often results in the removal of animals as nuisances. Although never tested, human habituation potentially reduces the fitness of adult females by reducing their offspring’s survival as well as their own, due to an increased likelihood of human-caused mortality. Here, we tested this hypothesis in brown bears inhabiting Shiretoko National Park, Japan. We estimated the frequency of human-caused mortality of independent young (aged 1–4 years) born to mothers living in areas with different maternal levels of human habituation and different proximities to areas of human activity. The overall mortality rate was higher in males than in females, and in females living near a town than those in a remote area of park. Surprisingly, more than 70% of males born to highly habituated mothers living around a remote wildlife protection area were killed by humans; this proportion is greater than that for males born to less-habituated mothers living in almost the same area. The current study clarified that interactions among maternal human habituation, birthplace (proximity to town), age, and sex determine the likelihood of human-caused mortality of brown bears at an early stage of life.

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“…In some cases for which a bear did not stand upright, or his/her sexual characteristic was unavailable, DNA analyses (by use of hairs they rubbed on the trap) revealed that he or she had reproduced in the past. Parentage analysis using microsatellite markers has been conducted in brown bear populations in the study area [52] and was partially used as a tool for the determination of sex-age classes in this study, e.g., bears with reproductive experience revealed by DNA-based parentage analysis, were categorized as adults. In addition, males ≥ 8 years of age [56], females ≥ 4 years of age [59], and bears ≤ 3 years of age, revealed by genetical identification and/or parentage analysis, were categorized as adult males, adult females, and sub-adults, respectively.…”

Section: Sex-age Classificationmentioning

confidence: 99%

Diel and monthly activity pattern of brown bears and sika deer in the Shiretoko Peninsula, Hokkaido, Japan

Jimbo

ADACHI

Shirane

et al. 2022

The Journal of Veterinary Medical Science

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Mammals exhibit several types of diel activity pattern, including nocturnal, diurnal, crepuscular, and cathemeral. These patterns vary inter-and intra-specifically and are affected by environmental factors, individual status, and interactions with other individuals or species. Determining the factors that shape diel activity patterns is challenging but essential for understanding the behavioral ecology of animal species, and for wildlife conservation and management. Using camera-trap surveys, we investigated the species distributions and activity patterns of terrestrial mammals on the Shiretoko Peninsula, Hokkaido, Japan, with particular focus on brown bears and sika deer. From June to October 2019, a total of 7,530 observations were recorded by 65 camera-traps for eight species, including two alien species. The diel activity pattern of brown bears was diurnal/crepuscular, similar to that of bears in North America, but different from European populations. Bear observations were more frequent during the autumnal hyperphagia period, and adult females and sub-adults were more diurnal than adult males. In addition, bears inside the protected area were more diurnal than those outside it. These findings suggest that appetite motivation, competitive interactions between conspecifics, and human activities potentially affect bear activity patterns. Similar to other sika deer populations and other deer species, the diel activity patterns of sika deer were crepuscular. Deer showed less variation in activity patterns among months and sex-age classes, while adult males were observed more frequently during the autumn copulation period, suggesting that reproductive motivation affects their activity patterns.

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Incidence of Multiple Paternity and Inbreeding in High-Density Brown Bear Populations on the Shiretoko Peninsula, Hokkaido, Japan

Cited by 45 publications

References 77 publications

Monitoring follicular dynamics to determine estrus type and timing of ovulation induction in captive brown bears (<i>Ursus arctos</i>)

Monitoring follicular dynamics to determine estrus type and timing of ovulation induction in captive brown bears (<i>Ursus arctos</i>)

Maternal human habituation enhances sons’ risk of human-caused mortality in a large carnivore, brown bears

Diel and monthly activity pattern of brown bears and sika deer in the Shiretoko Peninsula, Hokkaido, Japan

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