Genetic influences on reproduction of female red deer (Cervus elaphus) (2) seasonal and genetic effects on the superovulatory response to exogenous FSH

This study evaluated the influences of seasons and genotype on the superovulatory response to a standardised oFSH regimen in red deer (Cervus elaphus scoticus) and its hybrids with either wapiti (C.e. nelsoni) or Père David's (PD) deer (Elaphurus davidianus). Adult red deer (n=9), F(1) hybrid wapiti x red deer (n=6), and maternal backcross hybrid PD x red deer (i.e., 14 PD hybrid; n=9) were kept together in the presence of a vasectomised stag for 13 months. At 6 weekly intervals, all hinds received a standardised treatment regimen used routinely to induce a superovulatory response in red deer hinds, with 10 consecutive treatments spanning an entire year. This involved synchronisation with intravaginal progesterone devices and delivery of multiple injections of oFSH (equivalent to 72 units NIH-FSH-S(1)). Laparoscopy to assess ovarian response was performed 6-7 days after the removal of the devices. Both season and genotype had significant effects on ovulation rate (OR) and total follicular stimulation (TFS) (P<0.05). For all the three genotypes, ovarian responses were highest from March to November (breeding season) and lowest in the period from December to January, inclusive. Mean OR for red deer hinds ranged from 3.7 to 1.8 during the breeding season, with no observable trend. All red deer hinds were anovulatory during December and January. A similar pattern occurred for 14 PD hybrids, although mean OR during the breeding seasons were twofold lower than for the red deer. For F(1) wapiti hybrids, the first two treatments in March and April resulted in the highest mean OR observed (15.6 and 11.7, respectively). Thereafter, mean values ranged between 6.3 and 4.7 for the remainder of the breeding season. Furthermore, mean OR of 3.0 and 0.5 were recorded in December and January, respectively. For the red deer and F(1) wapiti hybrids, between-hind variation in OR was not randomly distributed across the treatment dates, indicating that the individuals varied significantly in their ability to respond to oFSH, at least within a given season.In conclusion, the study has shown that relative to red deer, F(1) wapiti hybrid hinds exhibit a higher sensitivity to oFSH, whereas 14 PD hybrid hinds have a lower sensitivity. However, individual variation within genotype was very marked. A seasonal effect was apparent for all genotypes, although some F(1) wapiti hybrid hinds exhibited ovulatory responses throughout the year.     

A phylogenetic comparison of red deer and wapiti using mitochondrial DNA

A phylogeny was constructed for red deer/wapiti (Cervus elaphus) subspecies using sequence data from the control region of mitochondrial DNA (mtDNA). The tree was rooted using Cervus nippon (sika deer), Cervus albirostris (Thorold's white-lipped deer), and several Odocoileinae species. A division between the mtDNA haplotypes of red deer (European) and wapiti (Asian/North American) corresponds to subspecies found on opposite sides of the Himalayan Mountains and Gobi, which suggests wapiti should be reconsidered for the status of C. canadensis. Using parsimony and distance analysis, red deer and wapiti are derived from a single recent common ancestor, which is consistent with current taxonomy that recognizes the subspecies of Cervus elaphus as monophyletic group. However, maximum-likelihood analysis using weighted transitional substitutions caused red deer to form a sister group to sika deer (Cervus nippon) and wapiti. A phenetic comparison revealed wapiti also share more nucleotide similarities with sika deer, although approximately 5% sequence divergence separates wapiti, sika, and red deer. Phylogenetic evidence from the cytochrome b sequences corroborated observations from the control region. Observations from this study suggest that the species status of wapiti should be reinstated.     

Genetic analysis of erythrocyte superoxide dismutase polymorphism in the genus Cervus

A study of erythrocyte superoxide dismutase in Cervus dama, Cervus elaphus, Cervus nippon and Cervus elaphus x Cervus nippon hybrids has revealed a polymorphism of this enzyme system in Cervus elaphus as well as in the hybrid population. Genetic analysis suggests that this enzyme system is controlled by one gene locus with two codominant alleles. The allele frequencies allow a clear discrimination between the hybrid population and the red deer population, whereas the fallow deer are fixed for the allele which is most common in red deer. The comparison of the genotypic structures with the Hardy-Weinberg structure shows a slight excess of homozygotes in all populations, but the deviation is significant only for the hybrid population as well as one red deer population. Genetic variation within and differentiation between demes is quantified using different measures. Finally, some management implications of these first results are discussed.     

Phylogenetic relationships among european red deer, wapiti, and sika deer inferred from mitochondrial DNA sequences

We determined the mitochondrial cytochrome b gene sequences (1140 bp) of one subspecies of the European red deer (Cervus elaphus in Europe), three subspecies of the wapiti (C. elaphus in Asia and North America), and six subspecies of the sika deer (C. nippon in Japan). Our phylogenetic analysis revealed the monophyly of the European red deer, that of the wapiti, and that of the sika deer. The wapiti, however, was shown to be more closely related to the sika deer than to the European red deer. This is in conflict with traditional morphological results, which suggest a close sister group relationship between the wapiti and the European red deer. The divergence time between the European red deer and the wapiti plus the sika deer was estimated to be approximately 0.80 Ma, and that between the wapiti and the sika deer was estimated to be 0.57 Ma. The sika deer was subdivided into two subspecies groups, and the wapiti was also found to consist of an Asian group and a North American group.     

Assessing the impact of past wapiti introductions into Scottish Highland red deer populations using a Y chromosome marker

As with other many game species in Europe, introductions of non-native stock to supplement Scottish red deer populations in an attempt to improve hunting trophy are well reported. These introductions included wapiti (Cervus elaphus canadensis or Cervus canadensis), a species two to three times heavier than the Scottish red deer. However, the effect of these past introductions of wapiti into Scottish red deer populations has not yet been assessed. In this study we sequenced a Y-chromosome marker (Zfy) from 104 collected in three neighbouring estates in the Scottish Highlands including one of the areas with the highest number of wapitis introduced in Scotland, and 45 red deer from an English deer park where introduction of wapiti and subsequent crosses with red deer were a common practice. Analyses revealed that all individuals presented red deer Y-chromosome sequences therefore suggesting a low impact of past introductions of wapiti in the populations under study. Sequencing and phylogenetic analyses of Zfy sequences for four additional deer species revealed that phylogenetic relationships were in agreement with previous mtDNA phylogenetic studies, and demonstrated the potential use of this marker to determine the direction of hybridization in F1 red-sika hybrids.     

Growth, development and parental investment in the spotted hyaena, Crocuta crocuta

In the Cervidae, sexual dimorphism in body mass, armament and structure of the breeding pelage appears to be, as in African antelope, a curvilinear function on openness of habitat. Sexes converge in characteristics towards male-like monomorphism in deer that hide in dense cover, as well as in gregarious, cursorial dwellers in open terrain. Relative antler mass correlates with weight dimorphism. The most cursorial species, the wapiti ( Cervus elaphus canadensis ) and the caribou ( Rangifer farandus ) converge towards male monomorphism, with the wapiti showing strong reduction in weight dimorphism (compared to red deer C. elaphus hippelaphus ), and structure of the breeding pelage, but not in weaponry. Male and female caribou converge strongly in the structure of the breeding pelage, less so in weaponry, and least in weight dimorphism; antlers in female caribou are thus comparable to horns in male-like females of plains bovids. In weight dimorphism, wapiti have almost reached the level of the African grazing antelopes of the tribes Alcelaphini and Orygini. Sexual dimorphism is maximal in mixed and concentrate feeders from semi-open landscapes.     

Induction of early breeding in red deer (Cervus elaphus) by melatonin

Lactating (N = 12) and non-lactating (N = 6) red deer hinds and one stag at pasture were given concentrates (500 g/head) containing melatonin (5 mg/head) daily at 16:00 h from 18 June to 16 October. The stag shed the antler velvet and started rutting 5 weeks ahead of untreated stags, and hinds had their first oestrus and ovulation of the breeding season in mid-September, 5 weeks in advance of control lactating (N = 9) and non-lactating (N = 5) hinds. Treated hinds were allowed to mate with the treated stag and control hinds ran in an adjacent paddock with an untreated stag. All hinds became pregnant during the study with all but 2 melatonin-fed hinds (1 lactating, 1 non-lactating) and 1 control hind (lactating) conceiving at the first oestrus. Melatonin-treated hinds lost slightly more live weight than did controls from June to November, but their suckled calves grew throughout at a rate similar to those of control hinds.     

Characterization of the erythrocyte superoxide dismutase allozymes in the deer Cervus elaphus

The cDNA sequences for Cu,Zn superoxide dismutase from two Cervus elaphus subspecies, North American wapiti and European red deer, were determined. The derived amino acid sequences showed two differences: residue 8 was Leu in wapiti and Met in red deer and residue 25 was His in wapiti and Asn in red deer. The extra positive charge at position 25 in the wapiti isoform accounted for its greater mobility towards the cathode during non-denaturing electrophoresis, a procedure widely used in the genetic analysis of deer. There was no difference in specific activity between the two Cu,Zn superoxide dismutase isoforms, but the wapiti isoform was slightly more susceptible to heat denaturation.     

Effects of free-ranging,semi-captive and captive management on the acoustics of male rutting calls in Siberian wapiti <Emphasis Type="Italic">Cervus elaphus sibiricus</Emphasis>

In male European red deer Cervus elaphus, rutting calls that are responsible for male reproductive success are higher in fundamental frequency in captivity than in the wild. This study compares the acoustics of stag rutting calls among wild-living, semi-captive and captive stags within an Asian subspecies of C. elaphus, the Siberian wapiti Cervus elaphus sibiricus. Male Siberian wapiti rutting calls (bugles) were collected using automated recording systems in three populations (wild-living, semi-captive and captive), all originated from the Altai/Khakasian region of Central Siberia (Russia). Selected 435 bugles (145 per population) were analysed spectrographically for 14 variables of the bugle high (>1 kHz) fundamental frequency (g0) and scored for shape of g0 contour: trapeze, descending or saddle. Among bugles, 74.3% had the trapeze contour, 23.7% had the descending contour and 2.1% had the saddle contour. The additional low (<0.2 kHz) fundamental frequency (f0) was found in 76.1% of bugles, whereas deterministic chaos was found in 16.8% of bugles. Bugles of captive stags were shortest and highest in frequency. The captive management selectively affected only bugles with the trapeze contour, whereas bugles with descending contour remained unaffected by variations of deer holding regime. Stag rutting bugles are subspecies-specific and may therefore serve as acoustic indicator of subspecies for the Siberian wapiti among other Asian and American subspecies of wapiti.     

Polymorphism and genetic control of erythrocyte 6-phosphogluconate dehydrogenase in the genus Cervus

A study of 11 enzyme systems in blood samples of Cervus dama, C. elaphus, C. nippon and hybrids C. elaphus X nippon has revealed an erythrocyte 6-phosphogluconate dehydrogenase polymorphism in the hybrid populations. Genetic analysis suggests that this enzyme is controlled by one gene locus with two codominant alleles, one specific for pure Japanese sika deer, the other for pure red deer as well as for fallow deer, while both alleles have been found in the red X sika hybrids.     

The effect of conception date on gestation length of red deer (Cervus elaphus)

Recent studies have demonstrated that gestation length of red deer (Cervus elaphus) is highly variable and influenced by various environmental factors, and this may confer survival advantages for neonates. The current study investigated the relationship between conception date and gestation length to test the hypothesis that within-herd synchrony of red deer births is facilitated by a 'push/pull' control over gestation length, such that hinds conceiving early and late in the breeding season have longer and shorter gestation periods, respectively. In Study 1, data on conception and calving dates were obtained for 393 naturally cycling hinds across two herds. In Study 2, conception and calving dates were obtained from 91 hinds in which oestrus/conception were artificially synchronised across a 4-week range of dates spanning the natural rut. Gestation length for each population was analysed by linear regression, fitting conception day followed by terms for the fixed effect which included hind age (pubertal vs. adult), hind genotype (Cervus elaphus scoticus vs. Cervus elaphus hippelaphus and their crossbreds), calf sex, sire genotype (Study 1 only), birth weight and year. In Study 1, both populations of naturally cycling hinds exhibited highly significant (P<0.001) negative slopes (-0.36, -0.49) for the regression of gestation length against conception date, with indications of a significant hind genotype effect favouring shorter overall gestation lengths for crossbred hinds. Other effects for hind age, calf sex, birth weight, sire genotype and year were not significant. In Study 2, in which conception dates were artificially induced, there was a highly significant negative slope (-0.19), with a notable but non-significant effect of hind age favouring shorter overall gestation length for primiparous (pubertal) hinds (P>0.05). Other effects for hind live weight, calf sex and calf birth weight were not significant. All data sets support the hypothesis, and indicate that for every 10 days difference in conception date there was a change in gestation length of 1.9-4.9 days. This hints at the adaptive importance of optimisation of birth date in wild populations of red deer but the precise physiological mechanisms remain to be resolved. It is postulated that variation in fetal age during the latter stages of pregnancy, when feed quality and voluntary feed intake cycles are in a state of flux, may drive differential growth trajectories for early and late conceived fetuses, leading to nutritional control over fetal maturation and induction of parturition. However, consideration is also given to a putative direct effect of prevailing photoperiod on control of parturition processes in red deer.     

Survey of hepatic and pulmonary helminths of wild cervids in Alberta, Canada

During the 1988 hunting season, livers and lungs from 263 mule deer (Odocoileus hemionus hemionus), 198 moose (Alces alces), 147 white-tailed deer (Odocoileus virginianus), and 94 wapiti (Cervus elaphus nelsoni) from Alberta (Canada) were collected for parasitological examination. Most of the samples (89%) were submitted by big game hunters throughout the province. Giant liver fluke (Fascioloides magna) was found in 9% of 22 yearling and 29% of 65 adult wapiti; 4% of 161 adult moose; and 2% of 97 adult white-tailed deer. The intensity of infection generally was low; however, one wapiti had over 600 flukes in the liver. Infections were restricted to alpine and montane regions in southwestern Alberta (97%) as well as boreal uplands of the Cypress Hills in southeastern Alberta (3%). Other parasites recorded included Taenia hydatigena cysts in liver of 61% of 191 moose and 14% of 247 mule deer. Dictyocaulus viviparus was found in lungs of 14% of 50 moose, 14% of 118 mule deer, 12% of 41 wapiti, and 6% of 54 white-tailed deer. Echinococcus granulosus cysts were found in lungs (and occasionally liver) of 37% of 51 moose. Incidental infections of Thysanosoma actinoides, Orthostrongylus macrotis, and Taenia omissa were recorded. Adult Dicrocoelium dendriticum were collected from liver of two wapiti, one mule deer, and one white-tailed deer from the Cypress Hills.     

Parelaphostrongylus andersoni (Nematoda: Protostrongylidae) in white-tailed deer from Michigan

Dorsal-spined larvae in fecal samples from free-ranging white-tailed deer (Odocoileus virginianus) in Michigan and Pennsylvania were used as a source of larvae to infect a hand-raised white-tailed deer fawn. The fawn receive 200 third-stage larvae and passed dorsal-spined larvae in feces 66 days later. Muscleworm (Parelaphostrongylus andersoni), and meningeal worm (Parelaphostrongylus tenuis) were recovered at necropsy. Two white-tailed deer and seven wapiti (Cervus elaphus) exposed to larvae of the source from Pennsylvania harbored only P. tenuis. This is the first report of P. andersoni in the midwestern United States and extends the known range of this muscleworm in free-ranging white-tailed deer. Concurrent infections of P. andersoni and P. tenuis have not been established previously in experimentally infected fawns.     

Artificial insemination of red deer (Cervus elaphus) with frozen-thawed wapiti semen

Semen collected from wapiti (Cervus elaphus) in Canada in 1983 was frozen in two extenders. In 1988, the semen was used to inseminate 200 red deer hinds on 2 farms in New Zealand. Oestrus was synchronized in the hinds with progesterone-impregnated intravaginal devices (CIDR); 200 iu pregnant mares' serum gonadotrophin was given to each hind on Day 11. The CIDRs were removed on Day 12 at 20/h, as the numbers of the hinds were recorded. On Day 14, 54-56 h after CIDR removal, the hinds were brought into the yards in the same batches and laparoscopically inseminated. Semen from three sires was used. The overall conception rate was 51%. Gestation length ranged from 239 to 247 days. One hind was lost at calving, 3 calves had to be hand raised and there were 2 neonatal calf deaths.     

Concentrations of insulin-like growth factor-I in adult male white-tailed deer (Odocoileus virginianus): associations with serum testosterone, morphometrics and age during and after the breeding season

Our understanding of insulin-like growth factor-I (IGF-I) in cervids has been limited mostly to its effects on antler development in red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama), and pudu (Pudu puda). Although IGF-I has been found to play a critical role in reproductive function of other mammals, its role in reproduction of deer is unknown. The objectives of the present study were to determine if serum levels of IGF-I change during the breeding season, assess whether age influences serum IGF-I, compare levels of IGF-I measured during and following the breeding season, and determine if IGF-I is associated with body and antler characteristics in free-ranging adult, male white-tailed deer (Odocoileus virginianus). We collected serum and morphometric data from hunter-harvested and captured white-tailed deer to investigate these objectives. Mean level of serum IGF-I during the breeding season was 63.6 ng/ml and was greatest in deer between 2.5 and 5.5 years old (57.4-79.9 ng/ml). Levels of serum IGF-I decreased by approximately 40% as the breeding season progressed, but levels were less in deer following the breeding season (34.6 ng/ml). Both body and antler size were associated positively with IGF-I when controlling for age. Serum testosterone was also associated positively with IGF-I. Levels of serum testosterone during the breeding season generally increased with age from 4.82 (1.5 years old) to 18.79 ng/dl (5.5 years old), but decreased thereafter. These data suggest that IGF-I may be an important hormone in breeding, male white-tailed deer.     

Artificial insemination following observational versus electronic methods of estrus detection in red deer hinds (Cervus elephus)

The objectives were to determine the efficacy of the HeatWatch (HW) electronic estrus detection system for monitoring behavioral estrus (including duration and intensity) in red deer hinds and to evaluate pregnancy rate to AI after detected estrus. Red deer hinds (Cervus elephus; n = 50) were allocated into two treatment groups: AI following synchronization (CIDR/PMSG) and observed estrus (induced estrus group: IE; n = 25) or AI following the detection of natural estrus (NE; n = 25) without hormonal treatment. Hinds were fitted with two HeatWatch (HW) electronic estrus detection transmitters, one above the tail (bottom) and one between the tuber coxae of the pelvic girdle (top), and visual observations for mounting activity began with the aid of young sterile red deer stags (18 months old) fitted with marking harnesses. Hinds in both groups were inseminated (10-12h after observed estrus) with frozen-thawed red deer semen using a transvaginal/cervical AI approach. Following a 26-day period of AI, hinds were placed with a mature fertile stag for an additional 30-day natural breeding period. Pregnancy diagnosis was performed 57 and 86 days after the start of AI. While the hinds were housed with the young stags, 82% were detected in estrus by visual appraisal of stag crayon marks, but only 32% of these were detected by HW. In contrast, in the hinds housed with the mature stag, 93% detected in estrus by crayon marks were also detected by HW. The top HW transmitter consistently recorded more mounts (P < 0.05) than the bottom transmitter. The pregnancy rate was numerically better in IE versus NE hinds (42% versus 29%, P > 0.10). In summary, there were no differences (P > 0.10) in the intensity (number) or duration of mounts (detected by HW) during estrus in IE versus NE hinds, and HW was most effective in detecting estrus in the presence of a heavier, mature stag versus a younger stag. When used in combination with transvaginal AI, an overall first-service pregnancy rate of 36.6% was achieved with AI of frozen-thawed semen in red deer hinds following detected estrus.     

Seasonal luteal cyclicity of pubertal and adult red deer (Cervus elaphus)

Reproductive failure of rising-two-year-old (R(2)) hinds and seasonal misalignment between calving and pastoral feed production are two factors limiting reproductive productivity of farmed red deer hinds in New Zealand. This study aimed to better understand processes around female puberty and breeding seasonality by describing the potential breeding season (i.e., oestrous cyclicity) of three red deer genotypes. A total of 27 hinds born in December 2005, representing Eastern European (Cervus elaphus hippelaphus), Western European (C.e. scoticus) and F1 crossbred (C.e. hippelaphus×scoticus) red deer, were blood sampled thrice-weekly for 7-8 months (February-September/October) across two years spanning the potential breeding seasons as R(2)'s in 2007 (i.e., puberty) and as adults in 2008. Plasma progesterone profiles were used to construct breeding cycle histories for each hind. Four R(2) hinds failed to initiate oestrous cycles (i.e., puberty failure). The remaining R(2) hinds, including all F1 hinds, exhibited between two and seven oestrous cycles. F1 hinds were significantly earlier to initiate, and later to terminate, cyclic activity, resulting in a longer mean pubertal breeding season (139 days) than for Eastern (86 days) and Western hinds (86 days). However, the data for R(2) hinds are confounded by live-weight, with the F1 hinds being significantly heavier than other genotypes. There were significant correlations between live-weight and seasonality parameters in 2007. All hinds were cyclic as adults in 2008, exhibiting between four and nine oestrous cycles, and a mean breeding season duration of between 132 (Western) and 137 (F1) days. For adult hinds there were no significant genotype differences in cyclic onset and cessation timing, and no observable relationships between live-weight and any reproductive parameter. However, the mean dates for the onset of the breeding season for all genotypes in 2008 were 2-3 weeks later than normally expected for adult hinds in New Zealand. The reasons for this are unclear but may relate to chronic stress of frequent animal handling. The study has demonstrated that puberty in red deer hinds is associated with a shorter potential breeding season than for adult hinds, and that perturbation of breeding activity appears to be quite common, leading to incidences of puberty failure and possibly other aberrant cyclic events. Live-weight×genotype interactions may influence puberty but do not appear to be strongly expressed in adults. However, the relatively late onset of oestrous cyclicity in the adult hinds may be an artefact of the study that has masked genetic influences on seasonal breeding patterns.     

Introgression through rare hybridization: A genetic study of a hybrid zone between red and sika deer (genus Cervus) in Argyll, Scotland

In this article we describe the structure of a hybrid zone in Argyll, Scotland, between native red deer (Cervus elaphus) and introduced Japanese sika deer (Cervus nippon), on the basis of a genetic analysis using 11 microsatellite markers and mitochondrial DNA. In contrast to the findings of a previous study of the same population, we conclude that the deer fall into two distinct genetic classes, corresponding to either a sika-like or red-like phenotype. Introgression is rare at any one locus, but where the taxa overlap up to 40% of deer carry apparently introgressed alleles. While most putative hybrids are heterozygous at only one locus, there are rare multiple heterozygotes, reflecting significant linkage disequilibrium within both sika- and red-like populations. The rate of backcrossing into the sika population is estimated as H = 0.002 per generation and into red, H = 0.001 per generation. On the basis of historical evidence that red deer entered Kintyre only recently, a diffusion model evaluated by maximum likelihood shows that sika have increased at approximately 9.2% yr-1 from low frequency and disperse at a rate of approximately 3.7 km yr-1. Introgression into the red-like population is greater in the south, while introgression into sika varies little along the transect. For both sika- and red-like populations, the degree of introgression is 30-40% of that predicted from the rates of current hybridization inferred from linkage disequilibria; however, in neither case is this statistically significant evidence for selection against introgression.