Genetic variation in domestic reindeer and wild caribou in Alaska

Reindeer ( Rangifer tarandus tarandus ) were introduced into Alaska 100 years ago and have been maintained as semidomestic livestock. They have had contact with wild caribou ( R. t. granti ) herds, including deliberate crossbreeding and mixing in the wild. Reindeer have considerable potential as a domestic animal for meat or velvet antler production, and wild caribou are important to subsistence and sport hunters. Our objective was to quantify the genetic relationships of reindeer and caribou in Alaska. We identified allelic variation among five herds of wild caribou and three herds of reindeer with DNA sequencing and restriction enzymes for three loci: a DQA locus of the major histocompatibility complex ( Rata-DQA1 ), K-casein and the D-loop of mitochondrial DNA. These loci are of interest because of their potential influence on domestic animal performance and the fitness of wild populations. There is considerable genetic variation in reindeer and caribou for all three loci, including five, three and six alleles for DQA , K-casein and D-loop respectively. Most alleles occur in both reindeer and caribou, which may be the result of recent common ancestry or genetic introgression in either direction. However, allele frequencies differ considerably between reindeer and caribou, which suggests that gene flow has been limited.     

Effects of weather and hunting on wild reindeer population dynamics in Hardangervidda National Park

Wild reindeer have a range that extends across the circumpolar region. In the last few decades, however, populations of wild reindeer have been on the decline. The reasons for these declines are poorly understood, but are suggested to be linked to both local and global climatic factors, disease, and human interference. Hardangervidda plateau in Norway is home to the largest wild reindeer population in Europe, and is at the southern end of its European range. This population is therefore of particular importance, particularly in the light of climate change. We investigated how weather and hunting have affected the wild reindeer population in Hardangervidda over the last two decades. Our findings suggest that the wild reindeer population in Hardangervidda is most affected by winter temperature and hunting, where colder temperatures and lower harvest rates typically result in higher growth rates. We did not find significant evidence for linear density dependence. Our results show trends across Hardangervidda, and give an indication of how region-wide weather and hunting pressure can affect the wild reindeer population. As new data emerge, future investigations should look into the existence and nature of density dependence and the influence of other weather and human disturbance related factors.     

Sex-specific differences in reindeer calf behavior and predation vulnerability

According to reproductive strategy theory, males in polygamousbreeding systems should invest in morphological or behavioralfeatures that increase reproductive success. When the earlydevelopment of such traits conflicts with predator protection,we expect that male calves will exhibit risk-taking behavior,such as high activity level and increasing distance from mother,to a greater extent than female calves. We investigated sexdifferences in mother–calf distance, calf activity levels,and calf mortality in a semi-domesticated reindeer (Rangifertarandus) population. The results show that male calves strayfarther away from their mothers, exhibit a higher level of locomotivebehavior in terms of play and walking, and are more vulnerableto predation than are female calves. Although mother–calfdistance increased over time in 1- to 6-month-old calves, noevidence was apparent for an increase in sex difference in mother–calfdistance over this period. The results suggest a trade-off betweenpredation vulnerability and investments in behavioral traitsthought to be important for future reproductive success andsuggest that these sex-related differences in behavior are apparentas early as 6 months of age.     

The impact of population bottlenecks on fluctuating asymmetry and morphological variance in two separate populations of reindeer on the island of South Georgia

In the early part of the 20^th century, whalers on South Georgia in the South Atlantic transported reindeer from Norway to establish a population from which they could cull animals for food. This happened twice, with reindeer obtained from the same source in each case, and with independent founder populations being established on separate parts of the island. As the exact number of founding males and females are known in each case, and as it was possible to obtain materials from the source population, this provided an unusually clear test of expectations about the impact of population bottlenecks on morphological and genetic diversity. In this study, we focus on the impact on morphological variation and on the relationship between genomic stress and indirect measures of fitness. We find that fluctuating asymmetry and morphological variation increased in each bottlenecked population and that the impact was somewhat stronger for the founder group that began with fewer females. Based on several skull measurements, there was also a significant trend for the reindeer in the bottlenecked populations to have smaller skulls. There were consistent correlations between individual genetic diversity and indirect measures of fitness, but these were weak and non‐significant after correction for type 1 error. Taken together, these data support the expectation that genomic stress has the potential to impact the expression of morphological phenotype in a large mammal and provide an opportunity to directly compare two parallel events. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 798–811.     

Abiotic factors influencing embryonic development, egg hatching, and larval orientation in the reindeer warble fly, Hypoderma tarandi

Wild-caught, tethered females of the reindeer warble fly, Hypoderma tarandi (L.) (= Oedemagena tarandi (L.)), (Diptera, Oestridae) were stimulated to oviposit on hairs of a reindeer hide. Newly laid eggs incubated at constant temperatures and relative humidities hatched within 3 days to 2 weeks, depending on the experimental conditions. Over a range of 7-40 degrees C, hatching only occurred between 20 and 37 degrees C. Eggs held at 100% relative humidity had lower hatchability and longer time to hatch relative to eggs held at 77% relative humidity. The average number of degree-days for hatching was 50.35. Between 20 and 33 degrees C there was a temperature-dependent linear trend in developmental rate, and the proportion of eggs hatching was highest, and least variable, at the mid-temperature ranges. The temperature range found in the natural host micro-habitat where H. tarandi commonly affix their eggs (close to the skin at the base of a host hair) was consistent with the experimental temperature treatments that produced the highest hatching rate. Newly emerged larvae displayed positive thermotaxis, while showing no phototaxic or geotaxic behaviour. Results indicate that constraints of the host environment, coupled with temperature-dependent hatching success, may impose a selective pressure on oviposition behaviour.     

Increased mass of reticulo-rumen tissue and contents with advancing age in Svalbard reindeer

Little is known about the effect of age on digestive processes in wild cervids. One potentially important mechanism is that tooth wear alters the occlusal surface topography, causing gradual loss of functionality. Mastication efficiency is crucial to digestion processes among ruminants, as a larger particle size is associated with longer retention times and potentially reduced digestion efficiency. Using data from 49 adult Svalbard reindeer Rangifer tarandus platyrhynchus females, we investigated whether the mass of reticulo-rumen (RR) contents and tissue and the amount of back fat showed age-related changes. Older animals had higher RR content mass than younger individuals. This is consistent with the prediction that altered particle size due to decreased mastication efficiency led to increased rumen retention time either through increased RR capacity or filling. Additional data on RR particle size distribution were available for a subset ( n =30). The correlation between the proportion of small particles (<1.0 mm) and RR contents was much weaker than the correlation between age and RR contents. This suggests that additional factors apart from particle size contribute to the age-related pattern in RR content mass. The mass of RR tissue in older animals was higher than that in younger animals. This possibly reflects an adaptation to the higher organ fill. The amount of back fat decreased with age, suggesting that alterations in digestion-related processes are not sufficient to compensate for reduced mastication efficiency in Svalbard reindeer. Our results present one possible link between foraging, digestive processes and life-history patterns.     

Allometry and variability of resource allocation to reproduction in a wild reindeer population

The differential allocation of energy to either reproductionor survival represents a major conflict with important implicationsfor patterns of life history. Here, we explore how covariationbetween maternal body weight and fetal weight vary accordingto fetal sex in a wild reindeer (Rangifer tarandus) populationduring two contrasting years. Maternal weights differed duringthe 2 years, probably because of a difference in populationdensity. We could not detect any change in the allocation toreproduction depending on female phenotypic distribution. Malefetuses were heavier than female fetuses, with the same relativedimorphism in both years. There was no support for a correlationbetween the sex of the fetus carried by a female and her weight.Our results suggest that the level of resource allocation toreproduction during the prenatal period is strongly determinedby female body weight and the allometric relationship betweenbody weight and metabolic rate. We discuss the consequencesof our results for population dynamics. We call for an integrationof inter- and intraspecific allometric approaches to betterunderstand constraints and variation in life-history traits.     

The impact of shrub browsing by mountain hare and reindeer in subarctic Sweden

Background: Climate warming has been causing an increase in tall shrub cover around the Arctic, however, mammalian herbivory has been shown to inhibit shrub expansion. Though the effect of reindeer (Rangifer tarandus) and many other mammals has been widely studied in this context, the role of the mountain hare (Lepus timidus) in subarctic Scandinavia remains unknown.

Aims: To quantify browsing from mountain hare and reindeer on tall shrubs in different vegetation types and to investigate differences in shrub preference between the two.

Methods: In the summers of 2013 and 2014, we counted signs of browsing by hare and reindeer on tall shrub species in 31 study plots at three alpine locations in the Scandes range, Sweden.

Results: Hare browsing was significantly more frequent than that by reindeer in two (dry-mesic heath and dry meadow) out of seven vegetation types studied. Reindeer browsing was significantly higher in the low herb meadow and Långfjället shrub heath. Two shrub species, Betula nana and Salix hastata, were significantly more browsed by hare, while reindeer browsing was significantly higher on S. phylicifolia and S. lapponum.

Conclusions: Our results show that mountain hares can cause extensive damage to tall shrubs in the subarctic and may have a stronger impact on shrub communities than previously recognised.     

Predator avoidance behaviour in wild and hatchery‐reared brown trout: the role of experience and domestication

Juvenile brown trout Salmo trutta from natural populations reacted to the presence of piscivorous brown trout by increasing the use of refuges. In contrast, second‐generation hatchery fish and the offspring of wild fish raised under hatchery conditions were insensitive to predation risk. The diel pattern of activity also differed between wild and hatchery brown trout. Second‐generation hatchery fish were predominantly active during daytime regardless of risk levels. Wild fish, however, showed a shift towards nocturnal activity in the presence of predators. These findings emphasize the potential role of domestication in weakening behavioural defences. They support the idea that the behavioural divergence between wild and domesticated individuals can arise from a process of direct or indirect selection on reduced responsiveness to predation risk, or as a lack of previous experience with predators.     

大兴安岭林区驯鹿夏季喜栖生境的生态特征

2012和2013年7—8月采用样线和样带调查结合的生境调查方法,对分布于我国大兴安岭西北麓的驯鹿的夏季偏好生境开展了对比研究,并对样地的海拔和乔木郁闭度等23个生境变量进行测量及比较.结果表明: 与对照样地相比,夏季驯鹿利用样地的海拔(926.9±0.8 m)、乔木郁闭度(17.9%±2.4%)、乔木胸径(35.5±2.1 cm)、乔木高度(8.2±0.5 m)、乔木密度(6.9±0.5 株·400 m^-2)及树桩数(1.3±0.2 个·400 m^-2)较大,但灌木均高(54.2±2.0 cm)较小(P<0.01).驯鹿夏季偏好选择坡度较缓的中坡生境,因其夏季喜栖生境的水源较多、隐蔽度和避风性较差,距人为干扰距离和牧民点距离均较远.主成分分析(PCA)表明,干扰强度(由距人为干扰距离及距牧民点距离变量组成)、乔木特征(由乔木的高度、密度、胸径和郁闭度变量组成)、地理特征(由坡位、坡向和土壤湿润度变量组成)、食物多度(地表植被盖度和灌木盖度变量构成)、开阔度(由隐蔽度和避风状况变量构成)和坡度是影驯鹿夏季生境选择的重要因素.这6个因子提供了70.7%的累积贡献率,主要反映了驯鹿夏季在喜栖生境选择中的食物资源、抗干扰性和反捕需求.从夏季喜栖生境的生态特征来看,驯鹿并没有被完全驯化.在保护和管理实践中,应使驯鹿种群及其核心栖息地免受高强度的人为干扰.     

Sickness behaviour associated with non-lethal infections in wild primates

Non-lethal parasite infections are common in wildlife, but there is little information on their clinical consequences. Here, we pair infection data from a ubiquitous soil-transmitted helminth, the whipworm (genus Trichuris), with activity data from a habituated group of wild red colobus monkeys (Procolobus rufomitratus tephrosceles) in Kibale National Park, Uganda. We use mixed-effect models to examine the relationship between non-lethal parasitism and red colobus behaviour. Our results indicate that red colobus increased resting and decreased more energetically costly behaviours when shedding whipworm eggs in faeces. Temporal patterns of behaviour also changed, with individuals switching behaviour less frequently when whipworm-positive. Feeding frequency did not differ, but red colobus consumption of bark and two plant species from the genus Albizia, which are used locally in traditional medicines, significantly increased when animals were shedding whipworm eggs. These results suggest self-medicative plant use, although additional work is needed to verify this conclusion. Our results indicate sickness behaviours, which are considered an adaptive response by hosts during infection. Induction of sickness behaviour in turn suggests that these primates are clinically sensitive to non-lethal parasite infections.     

Effects of natural winter pasture and commercial pellet on the ultrastructure of small intestinal epithelium in reindeer

Segments of small intestine (duodenum, jejunum and ileum) from slaughtered reindeer (Rangifer tarandus tarandus) grazing natural winter pastures (n=3) and reindeer fed commercially available pellets (RF-80) in winter (n=5) were collected and immediately fixed in McDowells fixative. Transmission electron microscopy was employed to investigate the ultrastructural features of the epithelium and lamina propria along the small intestine and to relate these to the different diets. Major differences in ultrastructural features were observed between the small intestinal enterocytes of reindeer fed the two diets. Enterocytes in reindeer fed the natural diet displayed a normal appearance with a dense cytoplasm and distinct microvilli. In contrast, reindeer fed the commercial diet showed damaged enterocytes amongst the normal cells. Abnormal changes included disintegration and loss of microvilli, cytoplasmic swelling, loss of membrane integrity and increases in the width of intercellular spaces, especially in the jejunum. The transport and holding of animals was supported by a grant from the Reindeer Husbandry Research Fund.     

The group size effect and synchronization of vigilance in the Tibetan wild ass

Vigilance behavior is considered as an effective strategy for prey species to detect predators.An individual benefits from living in a group by reducing the time spent being vigilant without affecting the probability of detecting a predator.However,the mechanism producing a decrease in vigilance with increasing group size is unclear.Many models of vigilance assume that group members scan independently of one another.Yet in recent studies,the other 2 patterns of vigilance,coordination and synchronization,were reported in some species.In 2 summers(2018 and 2019),we studied the group-size effect on vigilance and foraging of Tibetan wild ass in Chang Tang Nature Reserve of Tibet.We also tested whether individuals scan the environment independently,tend to coordinate their scans,or tend to synchronize their vigilance.The results showed that individuals decreased the time spent on vigilance with increasing group size,while increased the time spent foraging.Group members scanned the environment at the same time more frequently and there was a positive correlation between group members'behaviors,indicating that Tibetan wild asses tend to synchronize their vigilance.     

Comparison of genetically based antipredator behaviour in hatchery and wild coho fry from a coastal Oregon river: interpreting a negative result

Coho salmon Oncorhynchus kisutch fry derived from wild and hatchery stocks demonstrated no difference in responsiveness to an overhead fright stimulus in laboratory experiments.     

Summer distribution of wild reindeer in relation to human activity and insect stress

We examined the summer distribution of 2,500 wild reindeer (Rangifer tarandus tarandus) in southern Norway by eight aerial surveys across 8 years. Most of the reindeer were located at high elevations >1,400 m.a.s.l. (88% of the reindeer in 47% of the area) where insect stress was lower. Within high elevations, reindeer used areas <5.0 km from tourist resorts and major roads and <2.5 km from hiking trails less than expected from availability. A total of 65% of the reindeer were found in high-altitude areas without human development or only including closed maintenance roads, which constituted 21% of the area, likely because these areas gave shelter from both insect stress and human activity. We conclude that wild reindeer appear to select for insect relief areas reaching several kilometers away from human activity if such habitat is available. Infrastructure with associated human activity was found to be avoided in all surveys.     

When dogs look back: inhibition of independent problem-solving behaviour in domestic dogs (Canis lupus familiaris) compared with wolves (Canis lupus)

Domestic dogs have been recognized for their social sensitivity and aptitude in human-guided tasks. For example, prior studies have demonstrated that dogs look to humans when confronted with an unsolvable task; an action often interpreted as soliciting necessary help. Conversely, wolves persist on such tasks. While dogs'' ‘looking back’ behaviour has been used as an example of socio-cognitive advancement, an alternative explanation is that pet dogs show less persistence on independent tasks more generally. In this study, pet dogs, shelter dogs and wolves were given up to three opportunities to open a solvable puzzle box: when subjects were with a neutral human caretaker, alone and when encouraged by the human. Wolves were more persistent and more successful on this task than dogs, with 80% average success rate for wolves versus a 5% average success rate for dogs in both the human-in and alone conditions. Dogs showed increased contact with the puzzle box during the encouragement condition, but only a moderate increase in problem-solving success. Social sensitivity appears to play an important role in pet and shelter dogs'' willingness to engage in problem-solving behaviour, which could suggest generalized dependence on, or deference to, human action.