Functional Anatomy of the Omasum in High Arctic Svalbard Reindeer (Rangifer tarandus platyrhynchus) and Norwegian Reindeer (Rangifer tarandus tarandus)

The structure and fill of the omasum was investigated in summer and in winter in adult female reindeer living on the polar desert and tundra of the high Arctic archipelago of Svalbard and in sub-Arctic mountain habitats in northern Norway The mean total mass of the omasum in non-lactating adult female Svalbard reindeer was 467 g (0.65 g per 100 g live body mass (BM)) in September and 477 g (1.03 g per 100 g BM) in April. By contrast, the mean mass of the omasum in non-lactating adult reindeer in northern Norway was 534 g (0.83 g per 100 g BM) in September but only 205 g (0.35 g per 100 g BM p<0.05) in late March, owing to a decrease in both tissue mass and the wet mass of the contents of the organ. The mean absorptive surface of the omasum in Svalbard reindeer was 2300 cm2 in September and 2023 cm2 in April. In Norwegian reindeer, by contrast, the absorptive surface area decreased from 2201 cm2 in September to 1181 cm2 (p<0.05) in late March. The marked seasonal decline of omasal tissue and contents in Norwegian reindeer probably results from intake of highly digestible forage plants, including lichens, in winter. Svalbard reindeer, a non-migratory sub-species, survive eating poor quality fibrous vascular plants in winter. The absence of any marked seasonal change in the mass, total absorptive surface area or filling of the omasum in Svalbard reindeer in winter despite a substantial decline in body mass presumably reflects their need to maintain maximum absorption of nutrients, including volatile fatty acids, when feeding on such poorly fermentable forage.     

Evidence of Reciprocal Allonursing in Reindeer,Rangifer tarandus

The nursing of non‐offspring is referred to as allonursing. Reciprocity is a hypothesized cause of allonursing, but previous studies have not strongly supported or found no evidence in support for this hypothesis. Biological market theory was applied to 25 reindeer (Rangifer tarandus) does and their calves to investigate allonursing reciprocity across bouts and within dyads and assess the diversity of allonursing partners. We also investigated whether variation in allonursing would be associated to relatedness within dyads. We recorded both the occurrence and the duration of 1027 successful allonursing solicitations. All does allonursed, and only three of the 25 calves were not observed being allonursed. Throughout the study, 234 allonursing dyadic pairs were observed. Does allonursed the calves of several does, but allonursing was not distributed evenly among all potential partners. Twenty does were members of at least 1 dyad with a high degree of reciprocity based on the number of allonursing bouts exchanged within the dyad. We found evidence of both relative and absolute allonursing reciprocity at the group level. Across bouts and within dyads, the reciprocal allonursing indexes varied greatly both for frequency and for duration, with an average tendency towards unidirectionality. Evidence of strong reciprocity within dyads was found in 32 dyads for number of allonursing bouts and in 25 dyads for duration of allonursing bouts. Across bouts and within dyads, the number of allonursing bouts received was not influenced by relatedness, allonursing bouts given or absolute rank difference. Allonursing was not interchanged for rank‐related benefits. Our results provide evidence of reciprocal allonursing at the group level, across bouts and within dyads, and reciprocal allonursing among chosen partners. Our results point to the usefulness of applying the biological market theory to allonursing and of considering allonursing as a tradable commodity, traded for itself, among chosen partners.     

The Effect of Blood Sampling on Plasma Cortisol in Female Reindeer (Rangifer tarandus tarandus L)

A major response of the body to stress is the secretion of adrenocorticotrophic hormone (ACTH) by the adenohypophysis resulting in increased blood Cortisol levels. Corticotropin releasing factor (CRF) controls the release of ACTH, mediating a direct effect at the level of the pituitary (Guillame et al. 1992). An animal's perception of a stressful event and the resulting increase in Cortisol production can be influenced by previous experience, season, time of day, and the animal's sex, age, and condition (Dantzer & Mormède 1983, Moberg 1985).     

The collection and examination of semen of the Reindeer (Rangifer tarandus)

Semen was collected from all the mature Reindeer bulls (9) in the Glenmore herd, both normal and vasectomized. Nineteen samples of semen were obtained. Reindeer semen is a viscous fluid, generally amber in colour: after vasectomy its viscosity is much lower. The mean volume of the ejaculates was 0–5 ml. and mean sperm density 467 × 10⁴ spermatozoa. Motility was low in comparison with other mammals and the proportion of eosinophilic spermatozoa was high (74.5%). Other determinations included measurements of the size of unstained spermatozoa, and of fructose and citric acid concentration in the semen.     

The Distribution of Sudoriferous Glands in the Hairy Skin of Reindeer (Rangifer tarandus L.)

Skin samples were taken from forest reindeer (Rangifer tarandus L.) in order to study the distribution of apocrine tubular glands. Glands with well-developed secretory epithelium were restricted to certain areas of the body, namely the foreleg pit, a narrow strip on the belly, the groin and on the legs. Well-developed glands were also found in the oral angle and in the rump patch. The greatest amount was found in the ventral interdigital skin of both fore and hindfeet. In other parts of the body could only the excretory duct and a thin walled extension but no developed secretory epithelium be seen.     

Evidence for Strategic Sex Allocation in the Guppy (Poecilia reticulata): Brood Sex Ratio and Size Predict Subsequent Adult Male Mating Success

Sex allocation theory predicts that females should produce more sons when the reproductive success of sons is expected to be high, whereas they should produce more daughters, not daughters when the reproductive success of sons is expected to be low. The guppy (Poecilia reticulata) is a live‐bearing fish, and female guppies are known to produce broods with biased sex ratios. In this study, we examined the relationship between brood sex ratio and reproductive success of sons and daughters, to determine whether female guppies benefit from producing broods with biased sex ratios. We found that sons in male‐biased broods had greater mating success at maturity than sons in female‐biased broods when brood sizes were larger. On the other hand, the reproductive output of daughters was not significantly affected by brood sizes and sex ratios. Our results suggest that female guppies benefit from producing large, male‐biased brood when the reproductive success of sons is expected to be high.     

Relation Between Testosterone Levels in Serum and Proteolytic Activity in the Neck Muscles of the Norwegian Reindeer (Rangifer tarandus tarandus)

The characteristic hypertrophying of the male reindeer neck muscles during the rutting period, which coincides with the rise in serum testosterone levels, is found to be accompanied by a significant decrease in lysosomal proteolytic activity of the neck muscle cells. Conversely, during the period of neck muscle involution following the rapid decline in serum testosterone after the rut, a marked increase in neck muscle proteolytic activity is found. These changes in lysosomal activity do not parallel the changes in feed consumption and nutritional stage of the animals during the rutting period. The lysosomal proteolytic activity of the male reindeer neck muscles thus may be, at least partly, under the control of sex steroid hormones.     

Population genetics of the native caribou (Rangifer tarandus groenlandicus) and the semi-domestic reindeer (Rangifer tarandus tarandus) in Southwestern Greenland: Evidence of introgression

Over the past centuries the native caribou ofWest Greenland has gone through extensive population size fluctuations, with reductionsas great as 90% in less than 20 years.Norwegian semi-domestic reindeer wereintroduced to the Nuuk area in 1952 because ofthe small number of caribou in Greenland.Although the reindeer and caribou wereinitially kept separated, mixing has occurredsince the 1970's. We investigated the genotypicstructure of caribou and reindeer in South-westGreenland, using five polymorphicmicrosatellite markers isolated from cattle,sheep, goat and red deer. A total of ninetysamples were collected, which included samplesfrom caribou of four different regions andsamples from two different reindeer herds.Based on the genetic variation of the fivemarkers, our results shows that the caribou andthe reindeer populations in the six regionssampled are genetically differentiated withineach group and the two subspecies aredifferentiated from each other. A likelyexplanation for the genetic isolation of thepopulations investigated is that naturalbarriers (glaciers and wide fjords) exists inthe area. Furthermore we found that introducedNorwegian domestic reindeer hybridized with thenative Greenlandic caribou in two areasneighbouring Nuuk.     

The Structure,Stability and Pheromone Binding of the Male Mouse Protein Sex Pheromone Darcin

Mouse urine contains highly polymorphic major urinary proteins that have multiple functions in scent communication through their abilities to bind, transport and release hydrophobic volatile pheromones. The mouse genome encodes for about 20 of these proteins and are classified, based on amino acid sequence similarity and tissue expression patterns, as either central or peripheral major urinary proteins. Darcin is a male specific peripheral major urinary protein and is distinctive in its role in inherent female attraction. A comparison of the structure and biophysical properties of darcin with MUP11, which belongs to the central class, highlights similarity in the overall structure between the two proteins. The thermodynamic stability, however, differs between the two proteins, with darcin being much more stable. Furthermore, the affinity of a small pheromone mimetic is higher for darcin, although darcin is more discriminatory, being unable to bind bulkier ligands. These attributes are due to the hydrophobic ligand binding cavity of darcin being smaller, caused by the presence of larger amino acid side chains. Thus, the physical and chemical characteristics of the binding cavity, together with its extreme stability, are consistent with darcin being able to exert its function after release into the environment.     

Plasma urea, creatinine, and urea: creatinine ratio in reindeer (Rangifer tarandus tarandus) and in Svalbard reindeer (Rangifer tarandus platyrhynchus) during defined feeding conditions and in the field.

Variation in plasma urea and creatinine concentration and plasma urea:creatinine ratio (U:C) were studied in semidomestic free-ranging reindeer (Rangifer tarandus tarandus) on the Norwegian mainland, in wild Svalbard reindeer (Rangifer tarandus platyrhynchus), and in captive reindeer maintained either on a lichen-based diet or a protein-rich concentrate to investigate whether these parameters could be used as indicators of the nutritional status of reindeer. In the mainland animals, plasma creatinine concentration was high in winter and early spring and decreased by two-thirds toward the summer. The overall range in mean plasma creatinine concentration (+/-SE) was from 90+/-1.26 to 280+/-2.88 micromol/L. Mean plasma urea concentration (+/-SE) varied from 2.46+/-0.10 in winter up to 17.44+/-0.29 mmol/L in summer and autumn. Month of sampling explained 65% and 90% of the variation in plasma urea and creatinine concentrations, respectively, indicating that seasonality in the diet had the greatest influence on these parameters. Reindeer given lichens as the only feed showed an increase in plasma creatinine and a decrease in plasma urea concentration. Food restriction caused a temporary elevation in urea level but had no significant effect on plasma creatinine concentration. The slight effect of energy intake on urea and creatinine levels was supported by the fact that severe undernutrition in the Svalbard reindeer population had only a small effect on plasma urea and creatinine levels. Protein-rich pellet feed increased plasma urea from around 3 mmol/L to above 10 mmol/L and reduced creatinine concentrations to less than 100 micromol/L, suggesting that the protein content of forage is an important determinant of these blood parameters. Mean U:C ratio (+/-SE) in plasma varied from 8.9+/-0.28 to 120.8+/-1.88. Ratios above 20 appeared when protein intake was low and energy intake was restricted or when protein intake was high. Low ratios occurred when protein intake was low but energy intake adequate. Plasma urea and creatinine concentrations and the U:C ratio showed complex dynamics that were affected by both season and the protein and feed intake. We conclude that they appear to be difficult to interpret as single measures of nutritional status of reindeer.     

Local Mating,Dispersal and Sex Ratio in a Gregarious Parasitoid Wasp

Parasitoid sex ratios can be greatly influenced by mating and dispersal behaviour. Many sex ratio models assume that mating is strictly local (only mated females disperse from the natal patch) and that a single male is sufficient to inseminate all females in a brood. Bethylids (aculeate parasitoids) have been used to test predictions of these models, but less attention has been paid to testing their underlying assumptions. We investigated the timing of eclosion, mating and dispersal in mixed-sex and single-sex broods of the bethylid wasp Goniozus nephantidis. In mixed-sex broods, almost all females mate before dispersal and a single male is sufficient to inseminate virtually all females, even when brood sizes are large. Males disperse from both mixed-sex and all-male broods, but males in all-male broods disperse more slowly. Virgin females disperse from all-female broods, which are common. Virgin females can produce a brood, mate with their own sons and subsequently produce mixed-sex broods, but their success rate is very low. Virgin females could potentially circumvent sex allocation constraints by superparasitizing mixed-sex broods, but when presented with hosts bearing mixed-sex broods they destroy all members of the initial brood before ovipositing. Because of the high prevalence of single-sex broods and dispersal of both sexes, the mating structure of G. nephantidis is unlikely to conform to the assumption of strict local mating.     

Effects of Male age and Size on Mating Success in the Bumblebee Bombus terrestris

In social insects, the reproductive strategies adopted by colonies emerge as a complex property of individual behaviours, but as yet we are often unable to fully explain them in evolutionary terms. In bumblebees, colonies adopt either a short-lived strategy specializing in male production, or a longer-lived strategy in which mainly new queens are produced, but this results in males emerging long before mates are available; this strategy can only easily be explained if older males are at a significant reproductive advantage. Here we examine how age and morphological characters influence mating success of male bumblebees. In two separate experiments in which single virgin males and females were confined together, we found that young males and heavy males mated more swiftly and copulated for less time compared to old males or lighter males, respectively. However, in competitive situations age proved to be unimportant and the only factors to influence mating success were the lengths of the fore and hind tibiae, with strong directional selection for long leg length. Fore and hind legs are both used in courtship, so both traits are associated with plausible mechanisms under selection. It has previously been argued that, in times of food stress, bumblebee colonies should produce males as male size is less likely to be strongly correlated with fitness than female size. Our results suggest that this may not be so, since aspects of male size directly impact on their mating success. Our results leave unexplained the emergence of males many days before new queens.     

The effect of cloprostenol in non-pregnant and pregnant Norwegian semi-domestic reindeer (Rangifer tarandus tarandus L)

Two non-pregnant and five pregnant 1.5-year-old semi-domestic reindeer were used to study the effect of cloprostenol given during the luteal phase of the oestrous cycle, or at two stages of pregnancy (early December, n = 3, and mid-January, n = 2). Blood samples were collected at 3-hourly intervals from immediately prior to treatment until 6–8 days after treatment, after which blood samples were collected every second day. Prior to each blood collection, the animals were observed for signs of oestrus. Plasma progesterone, oestradiol-17β, luteinizing hormone (LH) and 15-ketodihydro-PGF_2α were analyzed to characterize variations in ovarian function.Treatment with cloprostenol resulted in an immediate and rapid decrease in plasma progesterone concentrations in all treated animals. The fall in plasma progesterone was associated with increase in 15-ketodihydro-PGF_2α. Oestrus, indicated by standing behaviour, was observed on three out of four occasions in the two non-pregnant animals. The average duration of standing behaviour (oestrus) was 27 h (range: 24–30 h).Of the pregnant females that were treated with cloprostenol in the beginning of December (n = 3), two aborted between 72 and 96 h after treatment. One of these developed pyometra after abortion. In one female the foetus died 2 days after treatment, but was retained within the uterus until slaughter 2.5 months later. One of the two females that were treated in mid-January aborted between 62–65 h after injection. The other female retained a live foetus until slaughter in February. There were few endocrinological differences between animals that aborted and those that did not, though aborting animals had lower progesterone concentrations for a longer period of time after treatment.It was concluded that cloprostenol can be used during the luteal phase of the oestrous cycle to induce luteolysis and oestrus. When given during pregnancy, cloprostenol can induce abortion, though undesired side effects make it inappropriate for practical use.     

Aspects of nitrogen and mineral nutrition in Icelandic reindeer,Rangifer tarandus

Nitrogen and mineral (Fe, Mg, Na, K, and Ca) compositions of foodstuffs consumed by and dung produced by male, pregnant and lactating female adult Icelandic reindeer and calves were determined during May of 1992. Iron levels in foodstuffs are consistently above the reported toxicity level for similar-sized sheep (0.5 ppt) and may lead to iron toxicity when consumed by reindeer during periods of high lean body mass catabolism. Male and female reindeer meet nutrient requirements for all measured elements and nitrogen with the possible exception of calcium for males during antler growth.     

Size and composition of the wild reindeer Rangifer tarandus platyrhynchus population in the Southeast Svalbard Nature Reserve

Alendal, E., de Bie, S. and van Wieren, S. E. 1979. Size and composition of the wild reindeer Rangifer tarandus platyrhynchus population in the Southeast Svalbard Nature Reserve. Holarct. Ecol. 2: 101-107. In the summer of 1977 we studied the reindeer population on the islands Barentsøya and Edgeøya in the eastern part of the Svalbard archipelago. A total of 1374 reindeer were observed: 326 animals in the western parts of Barentsøya and 1048 animals on Edgeøya. Considering those parts of Edgeøya which were not visited, the total number of reindeer on Edgeøya was estimated at 1300 animals. The total number of reindeer was lower than in previous years. The decline probably was due to severe winter conditions in 1975/1976 and 1976/1977 confirmed by the fact that many carcasses and few yearlings were observed. Nearly all reindeer occurred on the coastal plains and in the valleys. These areas have the relatively richest vegetation. The average recruitment of the total population (counted) was 15.9%. The adult sex ratio was in favour of females: 59% females versus 41% males. There were differences both in the recruitment and in the adult sex ratio between three distinct areas on Edgeøya and between two on Barentsøya. These differences may be due to dissimilarities in food quality and feeding conditions caused by climate, and by small exchange of reindeer between the areas. The high frequency of shed male antlers on Frankenhalvøya and Talaveraflya, north and south coast of Barentsøya respectively, indicates that these areas belong to the wintering grounds of reindeer on this island. Concentrations of shed female antlers on Barentsøya were less pronounced. The highest frequency was in the areas Sjodalen and Kvistdalen-Talaveraflya in the northwest and south respectively. Females may use these areas as late wintering grounds and possibly as calving areas. The average group size was 2.2 and the aggregation index 3.1. Seventytwo per cent of all groups, containing 48% of all reindeer, fell into group size 1 and 2. Males mostly were observed alone or together with one other animal. Females with calves most frequently occurred in groups of 2 and 4 animals.     

No Evidence for Significant Effect of Body Size and Age on Male Mating Success in the Spot-legged Treefrog

In anurans, body size and age of individuals generally affect male mating success. To test whether body size and age have effects on male mating success in the foam-nesting treefrog Polypedates megacephalus, a species widely distributed in China, we analyzed differences in body size and age between mated and unmated males for three populations using a Generalized Linear Mixed Model(GLMM). The results showed that mated males did not exhibit larger body size and older age than unmated males, suggesting that large and/or old male individuals did not have greater mating success than small and/or young males. Moreover, we also found a non-significant size-assortative mating pattern for all populations. Our findings suggest that body size and age of the foam-nesting treefrog do not affect male mating success.     

The musculoskeletal anatomy of the reindeer (Rangifer tarandus): fore- and hindlimb

Reindeer are numerous and widespread across the northern Holarctic. They are efficient long distance migrants and are able to cope with variations in substrate, such as ice, snow, uneven forest floor, wetland and flat grassland. However, as with the vast majority of quadrupedal vertebrates, no quantitative musculoskeletal anatomical information exists for these animals making it difficult to analyse the biomechanics of their locomotor behaviour. In this paper, we describe the gross anatomy of the limb musculature and quantify muscle and tendon morphology. Reindeer show slight hindlimb dominance in muscle and tendon mass, with muscle mass primarily proximally situated and tendon distally situated. Extensor muscles are heavier than flexors, but tendon mass is broadly similar in both extensors and flexors. The only complete quadrupedal data sets available for comparison are for hares and greyhounds making it difficult to identify general patterns. There are no obvious body mass effects and reindeer often comes out as intermediate between hare and greyhound. However, greyhound seem less hindlimb dominated in terms of muscle but both greyhound and hare have much higher masses of tendon compared to reindeer, particularly in their hindlimbs. All these quadrupeds show the commonly observed trait of much larger tendons and less massive muscles in distal limb segments; this reduces the inertial cost of accelerating the limbs. Generally, there is a dearth of available quantitative anatomical data of complete animals. This lack of information is hindering attempts to gain a better understanding of musculoskeletal function in quadrupeds.     

Adaptive regulation of body reserves in reindeer, Rangifer tarandus: a feeding experiment

The costs and benefits of body reserves fluctuate according to predictable factors such as season and life-cycle stage. Theory suggests that individuals at any time should regulate their body reserves according to the current balance between costs and benefits. Most studies on adaptive body mass regulation have been done on small passerine birds. In large vertebrates the costs associated with body reserves are assumed to be small and the reserves of these species are therefore thought to be dictated by environmental limitations. In this study we present experimental evidence for adaptive body mass regulation in female semi-domesticated reindeer ( Rangifer t. tarandus ). The risk of starvation in this species is highest in late winter. During snow melt this risk is reduced and the females should direct their effort towards the protection of their new born calf. To test how these seasonal and life-cycle changes are related to body mass regulation, we conducted a crossed experiment with two treatments where females were fed ad libitum during winter and spring respectively. During winter, the females from the fed group gained on average 12% of their initial body weight while the females from natural pastures lost on average 6% of their initial body weight. This strong response to winter feeding had no effect on reproductive performance, and the previously fed females lost their excess of body reserves during feeding in spring. This suggests that body reserves during winter primarily is used as an insurance against stochastic periods of starvation and that the females regulate their body reserves down to a set point in spring when the risk is reduced. We found however a positive correlation between initial female body weight and reproductive performance suggesting a close relationship between body weight and intrinsic individual qualities.