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Ecological resilience to ungulate overbrowsing is an important issue in forest ecosystems. After chronic herbivory, the recovery rate of understory vegetation and its related functions can be slow even with decreasing grazing intensity; thus, detecting elasticity during alternative successional trajectories is fundamental to understanding state perturbations. In this context, we focused on physical plant-soil feedback (functional interactions between plant growth and soil physical conditions) and evaluated elasticity and recovery processes according to deer density. The effects of 40 years of chronic herbivory by sika deer (average density 14.7 individuals km -2 ) on the recovery of understory plant communities and associated changes in soil physical properties in headwater catchments were assessed. Using 8 years of catchment-wide exclusion (fenced) and reduction (only culled; average 4.3 individuals km -2 ) treatments, plot sampling was conducted in 2010 (before treatment) and 2018 (after treatment). The recovery of vegetation and soil physical properties were evaluated, and functional plant-soil relationships and spatial variability were assessed to detect recovery processes during alternative successional trajectory. Woody species increased only under the exclusion treatment and the average soil bulk density was lower than that under reduction treatments. Soil bulk density was negatively correlated with root biomass in the fenced catchment, and root biomass was positively associated with woody species richness. Reduced soil bulk density (~0.5 g cm -3 ) was observed with greater root biomass and woody species richness on upper hillslopes in the deer-excluded catchment where plant coverage was minimal. Successional failure under the reduction treatment suggested slow recovery with a depressed threshold according to deer density, indicating a clockwise hysteretic response to deer density. Unlike plant coverage during the earlier period of overbrowsing, woody species root development led the recovery of functional physical plant-soil feedback; however, this was probably limited by the higher soil erosion rate in riparian areas and an under-developed herb layer. Our results highlight an alternative recovery trajectory of physical plant-soil feedback driven by an alternative plant element (woody roots) to recovery trajectory with increasing plant cover. However, riparian erosion and herb layer would still suppress recovery. Therefore, recovery might be slower at the landscape scale., (© 2022 The Ecological Society of America.)

Antler is the fastest growing and ossifying tissue in animals and it is a valuable model for cartilage/bone development. To understand the molecular mechanisms of chondrogenesis and osteogenesis of antlers, the PacBio Sequel II and Illumina sequencing technology were combined and used to investigate the mRNA expression profiles in antler tip, middle, and base at six different developmental stages, i.e., at 15th, 25th, 45th, 65th, 100th and 130th growth days. Consequently, we identified 24,856 genes (FPKM > 0.1), including 8778 novel genes. Besides, principal component analysis (PCA) revealed a significant separation between the growth stage (25th, 45th and 65th days) and ossification stage (100th and 130th days). COL2A1 gene was significantly abundant in the growth stage, whereas S100A7, S100A12, S100A8, and WFDC18 genes were abundant at the ossification stage. Subsequently screened to 14,765 significantly differentially expressed genes (DEGs), WGCNA and GO functional enrichment analyses revealed that genes related to cell division and chondrocyte differentiation were up-regulated, whereas those with steroid hormone-mediated signaling pathways were down-regulated at ossification stages. Additionally, 25 tumor suppressor genes and 11 oncogenes were identified and were predicted to interact with p53. Co-regulation of tumor suppressor genes and oncogenes is responsible for the special growth pattern of antlers. Together, we constructed the most complete sika deer antler transcriptome database so far. The database provides data support for subsequent studies on the molecular mechanism of sika deer antler chondrogenesis and osteogenesis., (© 2022. The Author(s).)

Large herbivores can exert top-down control on terrestrial plant communities, but the magnitude, direction, and scale dependency of their impacts remain equivocal, especially in temperate and boreal forests, where multiple disturbances often interact. Using a unique, long-term, and replicated landscape experiment, we assessed the influence of a high density of white-tailed deer (Odocoileus virginianus) on the spatiotemporal dynamics of diversity, composition, and successional trajectories of understorey plant assemblages in recently logged boreal forests. This experiment provided a rare opportunity to test whether deer herbivory represents a direct filter on plant communities or if it mainly acts to suppress dominant plants, which, in turn, release other plant species from strong negative plant-plant interactions. These two hypotheses make different predictions about changes in community composition and alpha and beta diversity in different vegetation layers and at different spatial scales. Our results showed that deer had strong effects on plant community composition and successional trajectories, but the resulting impacts on plant alpha and beta diversity patterns were markedly scale dependent in both time and space. Responses of tree and non-tree vegetation layers were strongly asymmetric. Deer acted both as a direct filter and as a suppressor of dominant plant species during early forest succession, but the magnitude of both processes was specific to tree and non-tree vegetation layers. Although our data supported the ungulate-driven homogenization hypothesis, compositional shifts and changes of alpha diversity were poor predictors of beta diversity loss. Our findings underscore the importance of long-term studies in revealing nonlinear temporal community trends, and they challenge managers to prioritize particular community properties and scales of interest, given contrasting trends of composition and alpha and beta diversity across spatial scales., (© 2022 The Ecological Society of America.)

The relative effect of top-down versus bottom-up forces in regulating and limiting wildlife populations is an important theme in ecology. Untangling these effects is critical for a basic understanding of trophic dynamics and effective management. We examined the drivers of moose (Alces alces) population growth by integrating two independent sources of observations within a hierarchical Bayesian population model. We used one of the largest existing spatiotemporal data sets on ungulate population dynamics globally. We documented a 20% population decline over the period examined. There was negative density-dependent population growth of moose. Although we could not determine the mechanisms producing density-dependent suppression of population growth, the relatively low densities at which we documented moose populations suggested it could be due to density-dependent predation. Predation primarily limited population growth, except at low density, where it was regulating. After we simulated several harvest scenarios, it appeared that harvest was largely additive and likely contributed to population declines. Our results highlight how population dynamics are context dependent and vary strongly across gradients in climate, forest type, and predator abundance. These results help clarify long-standing questions in population ecology and highlight the complex relationships between natural and human-caused mortality in driving ungulate population dynamics., (© 2022 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

Technological advances in the field of animal tracking have greatly expanded the potential to remotely monitor animals, opening the door to exploring how animals shift their behaviour over time or respond to external stimuli. A wide variety of animal-borne sensors can provide information on an animal's location, movement characteristics, external environmental conditions and internal physiological status. Here, we demonstrate how piecewise regression can be used to identify the presence and timing of potential shifts in a variety of biological responses using multiple biotelemetry data streams. Different biological latent states can be inferred by partitioning a time-series into multiple segments based on changes in modelled responses (e.g. their mean, variance, trend, degree of autocorrelation) and specifying a unique model structure for each interval. We provide six example applications highlighting a variety of taxonomic species, data streams, timescales and biological phenomena. These examples include a short-term behavioural response (flee and return) by a trumpeter swan Cygnus buccinator following a GPS collar deployment; remote identification of parturition based on movements by a pregnant moose Alces alces; a physiological response (spike in heart-rate) in a black bear Ursus americanus to a stressful stimulus (presence of a drone); a mortality event of a trumpeter swan signalled by changes in collar temperature and overall dynamic body acceleration; an unsupervised method for identifying the onset, return, duration and staging use of sandhill crane Antigone canadensis migration; and estimation of the transition between incubation and brood-rearing (i.e. hatching) for a breeding trumpeter swan. We implement analyses using the mcp package in R, which provides functionality for specifying and fitting a wide variety of user-defined model structures in a Bayesian framework and methods for assessing and comparing models using information criteria and cross-validation measures. These simple modelling approaches are accessible to a wide audience and offer a straightforward means of assessing a variety of biologically relevant changes in animal behaviour., (© 2022 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Abstract: It is well known that porosity has an inverse relationship with the mechanical properties of bones. We examined cortical and trabecular porosity of antlers, and mineral composition, thickness and mechanical properties in the cortical wall. Samples belonged to two deer populations: a captive population of an experimental farm having a high quality diet, and a free-ranging population feeding on plants of lower nutritive quality. As shown for minerals and mechanical properties in previous studies by our group, cortical and trabecular porosity increased from the base distally. Cortical porosity was always caused by the presence of incomplete primary osteons. Porosity increased along the length of the antler much more in deer with lower quality diet. Despite cortical porosity being inversely related to mechanical properties and positively with K, Zn and other minerals indicating physiological effort, it was these minerals and not porosity that statistically better explained variability in mechanical properties. Histochemistry showed that the reason for this is that Zn is located around incomplete osteons and also in complete osteons that were still mineralizing, whereas K is located in non-osteonal bone, which constitutes a greater proportion of bone where osteons are incompletely mineralized. This suggests that, K, Zn and other minerals indicate reduction in mechanical performance even with little porosity. If a similar process occurred in internal bones, K, Zn and other minerals in the bone may be an early indicator of decrease in mechanical properties and future osteoporosis. In conclusion, porosity is related to diet and physiological effort in deer. [Copyright &y& Elsevier]

The article discusses the glucocorticoids and climatic cues in the population of red deer in riparian areas. It discusses the impact of environmental challenges such as temperature, precipitations, and water level on the animal's annual pattern of secretions. An overview of the glucocorticoids production through the neuroendocrine system that reacts with physiological and behavioral changes is also provided.

Intraspecific phenotypic variation (PV) in deer is common, at times impressively diverse, and involves morphology, development, physiology, and behaviour. Until recently considered a nuisance in evolutionary and taxonomic studies, PV has become the primary target to study fossil and extant species. Phenotypes are traditionally interpreted to express primarily interactions of inherited genetic variants. PV certainly originates from different genotypes, but additional PV, referred to as phenotypic plasticity (PP), results from gene expression responsive to environmental conditions and other epigenetic factors. Usage of ‘epigenetics’ for PP has increased exponentially with 20316 published papers (Web-of-Science 1990 – May 2010), yet it does not include a single paper on cervids (1900 to the present). During the ‘genomic era’, the focus was on the primary DNA sequences and variability therein. Recently however, several higher order architectural genomic features were detected which all affect PV. (1) Genes: poli-genic traits; pleiotropic genes; poli-allelic genes; gene dosage (copy number variants, CNV); single nucleotide variance in coding and gene regulatory regions; mtDNA recombinations and paternal mtDNA inheritance.(2) Gene products: pleiotropic gene products; multiple protein structures through alternative splicing; variable gene product reactions due to gene dosage.(3) Gene expression: (i) epigenetic regulation at the DNA, nucleosomal and chromosomal levels; (ii) large-scale genomic structural variation (i.e. CNV imbalance); (iii) transcription factor proteins (TF), each regulating up to 500 target genes, with TF activity varying 7.5–25% among individual humans (exceeding variation in coding DNA by 300–1000×); (iv) non-protein-coding RNA (98.5% of genome) constituting maybe hundreds of thousands RNA signals; (v) gene expression responsive to external and internal environmental variation; (vi) transgenerational epigenetic inheritance (e.g. from ubiquitous non-gametic interactions, genomic imprinting, epistasis, transgenerational gene–diet interactions); (vii) epigenetic stochasticity resulting in random PP. A unique example of labile traits in mammals is the yearly regrowth of a complete appendage, the antler in cervids. Highly complex assortments of genotypes lead to a spectrum of phenotypes, yet the same spectrum can result if a single genotype generates highly complex assortments of epigenotypes. Although DNA is the template for the DNA–RNA–protein paradigm of heredity, it is the coordination and regulation of gene expression that results in wide complexity and diversity seen among individual deer, and per-generation variety of phenotypes available for selection are greater than available genotypes. In conclusion, epigenetic processes have fundamental influences on the great intraspecific PV found in deer, which is reflected in broad ranges of environmental conditions under which they can persist. Deer management and conservation of endangered cervids will benefit from appreciating the large inherent PV among individuals and the immense contribution of epigenetics in all aspects of deer biology and ecology. [ABSTRACT FROM AUTHOR]

During their annual regeneration, antlers are innervated by trigeminal sensory axons growing at the highest rate recorded for any adult mammal. Previous analyses established the presence in the antler of nerve growth factor and neurotrophin 3 neurotrophins, which may underlie this rapid nerve growth. We are currently exploring the expression of other molecules that may be involved in such growth (axon growth promoters) combining several gene-expression techniques. Preliminary results indicate the expression of different growth promoters in the antler velvet, five of them not previously described in deer. The expression of these molecules as well as others described in the literature suggests that antler velvet promotes axon growth. However, most promoters expressed in the velvet are also present in unmodified deer skin. Thus, it must be asked why axons grow so fast in the antler? To answer that question, we developed a series of in vitroexperiments using sensory neurons from adult and embryo rodents. These studies suggested that soluble proteins secreted by the velvet strongly promote neurite outgrowth. Using specific blocking antibodies, we demonstrated that nerve growth factor is partially responsible for these effects although other yet unidentified proteins seem also to be involved. The studies also showed that neither endocrine serum factors nor antler tissue substrate stimulate neurite outgrowth, although deep velvet layers cause neurite outgrowth orientation. [ABSTRACT FROM AUTHOR]

Annual full regeneration of deer antlers has been proved to be a stem cell-based process, and antler stem cells (ASC) reside in both antlerogenic periosteum (AP) and pedicle periosteum (PP). In this review, we first put forward a hypothesis that the closely associated skin is the primary component of ASC niche and then provide results testing this hypothesis. Membrane insertion experiments confirmed that interactions between ASC and the associated skin are indispensible for both antler generation and regeneration, and these are achieved through exchanging diffusible molecules. Intradermal AP transplantation study demonstrated that both epidermal and dermal papilla cells are involved in these interactions. Further, the AP inversion experiment indicated that the initial inductive signal originates from the ASC resident in the AP cellular layer, although the AP fibrous layer is naturally adjacent to skin. Experimental manipulation to the niche has profound effects on antler development. We believe that eventual identification of these interactive molecules will not only greatly enhance our knowledge of antler development, but also have significant impacts on regenerative medicine in general. [ABSTRACT FROM AUTHOR]

Alterations in cellular and chemical constituents in blood are indicators of physical or chemical restraint in deer. The aim of this study was to determine the effects of physical and chemical restraint on hematologic and biochemical analytes in captive brown brocket deer ( Mazama gouazoubira). Six adult deer were physically restrained and randomly anesthetized in a crossover design using 3 protocols (P). In P1, anesthesia was induced directly with isoflurane using a face mask and was maintained with isoflurane delivered by endotracheal tube. In P2, oral premedication with midazolam was followed 1 hour later by induction and maintenance of anesthesia with isoflurane, as in P1. In P3, intravenous anesthesia with a combination of ketamine, xylazine, and atropine was followed by anesthesia with isoflurane, as in P1. Blood was collected immediately after physical restraint (T0) and during anesthesia at 20-minute intervals (T15, T35, and T55). Hematologic and biochemical constituents were determined using manual methods or automated analyzers, with cortisol measured by enzyme immunoassay. During physical restraint, following food and water restriction, significant hemoconcentration, increased WBC count, and lower cortisol concentration were observed compared with results at T15, T35, and T55. During anesthesia, lymphocyte count was lower in P2 than P1, urea concentration was decreased at T15 using P2, and plasma glucose concentration was increased after T0 ( P<.01). Among the anesthetic protocols, there was a trend for decreased cortisol concentration using P2. Physical restraint and anesthesia affect some blood constituents in captive brown brocket deer, and midazolam premedication may modify the intensity of the stress response. [ABSTRACT FROM AUTHOR]

Abstract: In Europe the most important hosts maintaining Ixodes ricinus tick populations are deer. Therefore, excluding deer by fencing or culling are potential tick management tools. Here we test the hypothesis that deer act as vehicles for moving ticks between two distinct habitats: forest and open heather moorland. We utilised an ideal “natural experiment” whereby forests were either fenced or unfenced to prevent or allow deer to move between habitats. We aimed to test the hypothesis that deer cause a net movement of ticks from high tick density areas, i.e. forests, to low tick density areas, i.e. open moorland. We recorded I. ricinus and host abundance in 10 unfenced and seven fenced forests and their respective surrounding heather moorland. We found that fenced forests had fewer deer and fewer I. ricinus nymphs than unfenced forests. However, we found no evidence that fencing forests reduced I. ricinus abundance on adjacent heather moorland. Thus there was insufficient evidence for our hypothesis that deer cause a net movement of ticks from forest onto adjacent moorland. However, we found that deer abundance generally correlates with I. ricinus abundance. We conclude that fencing can be used as a tool to reduce ticks and disease risk in forests, but that fencing forests is unlikely to reduce ticks or disease risk on adjacent moorland. Instead, reducing deer numbers could be a potential tool to reduce tick abundance with implications for disease mitigation. [Copyright &y& Elsevier]

Debate within the popular and technical literature regarding predictability of antler size at maturity based on 1.5-year antler size in white-tailed deer (Odocoileus virginianus) has led to confusion and uncertainty within constituent groups. Koerth and Kroll (2008) provided measures of age-related antler development using recaptures of known-age males from 12 deer populations in southern Texas. Several design and analysis issues reduce the scope and validity of their conclusion that amount of growth in the first set of antlers was a poor predictor of antler growth at maturity. Although unstated, the statistical hypothesis they tested did not coincide with their specific conclusions. Using a simulation, we show that their methods were susceptible to measurement bias. Their results are applicable only to populations with similar culling and management programs. Additionally, we provide recommendations for future research projects that evaluate predictability of antler size at maturity based on antler size at younger ages. [ABSTRACT FROM AUTHOR]

Abstract: The extinct giant deer, Megaloceros giganteus, is among the largest and most famous of the cervids. Megaloceros remains have been uncovered across Europe and western Asia, but the highest concentrations come from Irish bogs and caves. Although Megaloceros has enjoyed a great deal of attention over the centuries, paleobiological study has focused on morphometric and distributional work until now. This paper presents quantitative data that have implications for understanding its sudden extirpation in western Europe during a period of global climate change approximately 10,600 14C years ago (ca. 12,500calendar years BP). We report here the first stable isotope analysis of giant deer teeth, which we combine with dental cementum accretion in order to document age, diet and life-history seasonality from birth until death. Enamel δ 13C and δ 18O measured in the second and third molars from seven individual giant deer suggest a grass and forb-based diet supplemented with browse in a deteriorating, possibly water-stressed, environment, and a season of birth around spring/early summer. Cementum data indicate that the ages of the specimens ranged from 6.5 to 14years and that they possessed mature antlers by autumn, similar to extant cervids. In addition, the possibility for combining these two techniques in future mammalian paleoecological studies is considered. The data presented in this study imply that Megaloceros would have indeed been vulnerable to extirpation during the terminal Pleistocene in Ireland, and this information is relevant to understanding the broader pattern of its extinction. [Copyright &y& Elsevier]

The annual regeneration of deer antlers is a unique developmental event in mammals, which as a rule possess only a very limited capacity to regenerate lost appendages. Studying antler regeneration can therefore provide a deeper insight into the mechanisms that prevent limb regeneration in humans and other mammals, and, with regard to medical treatments, may possibly even show ways how to overcome these limitations. Traditionally, antler regeneration has been characterized as a process involving the formation of a blastema from de-differentiated cells. More recently it has, however, been hypothesized that antler regeneration is a stem cell-based process. Thus far, direct evidence for the presence of stem cells in primary or regenerating antlers was lacking. Here we demonstrate the presence of cells positive for the mesenchymal stem cell marker STRO-1 in the chondrogenic growth zone and the perivascular tissue of the cartilaginous zone in primary and regenerating antlers as well as in the pedicle of fallow deer (Dama dama). In addition, cells positive for the stem cell/ progenitor cell markers STRO-1, CD133 and CD271 (LNGFR) were isolated from the growth zones of regenerating fallow deer antlers as well as the pedicle periosteum and cultivated for extended periods of time. We found evidence that STRO-1+ cells isolated from the different locations are able to differentiate in vitro along the osteogenic and adipogenic lineages. Our results support the view that the annual process of antler regeneration might depend on the periodic activation of mesenchymal progenitor cells located in the pedicle periosteum. The findings of the present study indicate that not only limited tissue regeneration, but also extensive appendage regeneration in a postnatal mammal can occur as a stem cellbased process. [ABSTRACT FROM AUTHOR]

Identifies regenerating antler cartilage as a site of osteoclastogenesis in vivo in deer. Tartrate-resistant acid phosphatase activity; Vitronectin receptor expression in antler tissue sections; Localization of calcitonin receptors; Multinucleated cell formation in vitro.

Presents a study which explored the nutritional consequences of dimorphism and provided a mechanism for explaining sexual segregation in dimorphic deer. Materials and methods; Metabolic requirements; Digestive responses.

Differential maternal allocation theory states that mothers will invest more heavily in the offspring sex that will secure higher reproductive output. Senescence theory is concerned with the gradual deterioration of physiological function with age. We analysed the offspring sex-dependent response of calf growth and milk traits to mother age in an Iberian population of captive red deer (Cervus elaphus) using a 22 year time series longitudinal data set. Previous studies revealed that there was little evidence for the differential allocation theory on milk traits and that most studies lacked proper control for confounding factors. Our results indicated that (i) calf growth was offspring male-biased, negatively affected by mother age and positively influenced by mother weight and parity, and (ii) there was no support for differential allocation offspring sex-dependence in milk traits (yield, energy density, fat, protein and lactose content). Our findings suggest that maternal allocation responds to offspring energy requirements, which are mainly driven by offspring body weight, and contingent on mother age and weight and previous maternal reproductive effort., (© 2022. The Author(s).)

Predator search efficiency can be enhanced by anthropogenic landscape change, leading to increased predator-prey encounters and subsequent prey population declines. Logging increases early successional vegetation, providing ungulate forage. This increased forage, however, is accompanied by linear feature networks that increase predator hunting efficiency by facilitating predator movement and increasing prey vulnerability. We used integrated step selection analyses to weigh support for multiple hypotheses representing the combined impact of logging features (cutblocks and linear features) on wolf (Canis lupus) movement and habitat selection in interior British Columbia. Further, we examine the relationship between logging and wolf kill-sites of moose (Alces alces) identified using spatiotemporal wolf location cluster analysis. Wolves selected for linear features, which increased their movement rates. New (0-8 years since harvest) cutblocks were selected by wolves. Moose kill-sites had a higher probability of occurring in areas with higher proportions of new and regenerating (9-24 years since harvest) cutblocks. The combined selection and movement responses by wolves to logging features, coupled with increased moose mortality sites associated with cutblocks, indicate that landscape change increases risk for moose. Cumulative effects of landscape change contribute to moose population declines, stressing the importance of cohesive management and restoration of anthropogenic features., (© 2022. The Author(s).)

Recovering endangered species is a difficult and often controversial task that challenges status quo land uses. Southern Mountain caribou are a threatened ecotype of caribou that historically ranged in southwestern Canada and northwestern USA and epitomize the tension between resource extraction, biodiversity conservation, and Indigenous Peoples' treaty rights. Human-induced habitat alteration is considered the ultimate cause of caribou population declines, whereby an increased abundance of primary prey-such as moose and deer-elevates predator populations and creates unsustainable caribou mortality. Here we focus on the Klinse-Za and Quintette subpopulations, part of the endangered Central Group of Southern Mountain caribou in British Columbia. These subpopulations were trending toward immediate extirpation until a collaborative group initiated recovery by implementing two short-term recovery actions. We test the effectiveness of these recovery actions-maternity penning of adult females and their calves, and the reduction of a primary predator, wolves-in increasing vital rates and population growth. Klinse-Za received both recovery actions, whereas Quintette only received wolf reductions, providing an opportunity to test efficacy between recovery actions. Between 1995 and 2021, we followed 162 collared female caribou for 414 animal-years to estimate survival and used aerial counts to estimate population abundance and calf recruitment. We combined these data in an integrated population model to estimate female population growth, total population abundance, and recovery action effectiveness. Results suggest that the subpopulations were declining rapidly (λ = 0.90-0.93) before interventions and would have been functionally extirpated (<10 animals) within 10-15 years. Wolf reduction increased population growth rates by ~0.12 for each subpopulation. Wolf reduction halted the decline of Quintette caribou and allowed them to increase (λ = 1.05), but alone would have only stabilized the Klinse-Za (λ = 1.02). However, maternity penning in the Klinse-Za increased population growth by a further ~0.06, which when combined with wolf reductions, allowed populations to grow (λ = 1.08). Taken together, the recovery actions in these subpopulations increased adult female survival, calf recruitment, and overall population growth, more than doubling abundance. Our results suggest that maternity penning and wolf reductions can be effective at increasing caribou numbers in the short term, while long-term commitments to habitat protection and restoration are made., (© 2022 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

Temperate zone ungulates like red deer (Cervus elaphus) show pronounced seasonal acclimatisation. Hypometabolism during winter is associated with cardiovascular changes, including a reduction in heart rate (fH) and temporal peripheral vasoconstriction. How anaesthesia with vasoactive substances such as medetomidine affect the seasonally acclimatised cardiovascular system is not yet known. We anaesthetised eleven healthy female red deer with medetomidine (0.1 mg/kg) and tiletamine/zolazepam (3 mg/kg) twice in winter (ad libitum and restricted feed) and in summer (ad libitum and restricted feed), with a two-week washout-period in-between, to test for the effect of season, food availability and supplementation with omega-3 or omega-6 polyunsaturated fatty acid (PUFA) on fH and arterial blood pressure (ABP) during anaesthesia. Six animals received pellets enriched with omega-6 fatty acids (FA), and five animals with omega-3 FA. Anaesthesia significantly decreased fH in summer but not in winter and ABP was lower in winter (p < 0.05). The combination of omega-6 FA enriched pellets and food restriction resulted in a lower fH and higher ABP during anaesthesia with more pronounced changes in winter (p < 0.001). Our results demonstrate that season, food availability and type of PUFA supplementation in red deer affect the cardiovascular system during anaesthesia., Competing Interests: The authors have declared that no competing interests exist.

Landscape change alters species' distributions, and understanding these changes is a key ecological and conservation goal. Species-habitat relationships are often modelled in the absence of syntopic species, but niche theory and emerging empirical research suggests heterospecifics should entrain (and statistically explain) variability in distribution, perhaps synergistically by interacting with landscape features. We examined the effects of syntopic species in boreal mammals' relationship to landscape change, using three years of camera-trap data in the western Nearctic boreal forest. Using an information-theoretic framework, we weighed evidence for additive and interactive variables measuring heterospecifics' co-occurrence in species distribution models built on natural and anthropogenic landscape features. We competed multiple hypotheses about the roles of natural features, anthropogenic features, predators, competitors, and species-habitat interaction terms in explaining relative abundance of carnivores, herbivores, and omnivores/scavengers. For most species, models including heterospecifics explained occurrence frequency better than landscape features alone. Dominant predator (wolf) occurrence was best explained by prey, while prey species were explained by apparent competitors and subdominant predators. Evidence for interactions between landscape features and heterospecifics was strong for coyotes and wolves but variable for other species. Boreal mammals' spatial distribution is a function of heterospecific co-occurrence as well as landscape features, with synergistic effects observed for most species. Understanding species' responses to anthropogenic landscape change thus requires a multi-taxa approach that incorporates interspecific relationships, enabling better inference into underlying processes from observed patterns., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Recent research has challenged the idea that cervid antlers are such costly traits, supporting the assertion early-life antler investment is an honest signal of adult phenotypic quality. However, inferences were made based on antler measurements while growing (velvet) and thus, studies on fully-formed clean antlers are needed to avoid possible bias caused by the inter-individual variation in antler growth phenology. We studied a semi-captive population of European roe deer inhabiting a sub-Mediterranean area (Valsemana research station) and living under optimal conditions (ad libitum food supply and veterinary care). Based on repeated measurements taken from 146 individuals, we assessed whether allocation to secondary sexual traits during early life affected body mass or antler development during adulthood. Furthermore, we evaluated which body measurements better predicted future male quality. Additionally, using 488 individuals, we described age-class-specific variation in male body measurements and assessed the decline in antler size between adult and senescent stages (i.e. magnitude of senescence). Results agree with the assertion that there is no negative effect of a high investment in antler during early life on adult antler size or body mass, but we suggest the use of clean antlers as a more robust and reliable measure. The variables that better predicted body mass during adulthood were yearling body mass and body size at 6 months. Antler score between 10 and 18 months resulted in the best indicator of adult antler size. Finally, we support the idea that the magnitude of senescence in antler size is smaller in environments with higher resource availability during winter., (© 2021 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

Ethnopharmacological Relevance: Velvet antler extracts (VAE) are composed of a variety of active substances and growth factors, and have been reported to improve sleep quality and memory., Aim of the Study: We aimed to explore the protective effects and mechanism of action for VAE on Alzheimer's disease (AD) using a transgenic Caenorhabditis elegans model., Materials and Methods: C. elegans were cultivated at 40% relative humidity on solid nematode growth medium (NGM) containing live E. coli (OP50) as the food source, with Strain N2 (normal) held at 20 °C and the CL4176s (transgenic) held at 16 °C. AD-like aggregation of Aβ peptide in the CL4176s strain is induced by lifting the temperature to 25 °C. Nematodes were treated with three types of VAEs and Resveratrol (positive control). Analyses included qRT-PCR for quantification of gene transcripts of interest; ELISA for measuring levels of amyloid-β protein; Thioflavin T fluorescent staining for localizing Aβ depositions; assays for reactive oxygen species (ROS) and superoxide dismutase activity (SOD)., Results: VAEs reduced β-amyloid peptide (Aβ) toxicity in the transgenic C. elegans model. An enzymatically-digested VAE (EDVAE) was superior to both a cold-water VAE (CWVAE) and a hot-water VAE (HWVAE) from the same velvet antler. EDVAE treatment reduced the severity of the Aβ-induced paralysis phenotype and decreased the amount of Aβ deposits in the AD model nematodes, and these effects were found to be significantly better than that of the positive control Resveratrol. In addition, EDVAE treatment reduced production of ROS (induced by Aβ), enhanced SOD activity, and elevated expression levels of antioxidant-related transcription factors, although it is not known whether these effects were achieved directly or indirectly., Conclusion: EDVAE had a protective role in Aβ-induced toxicity in the transgenic AD nematodes, possibly through reducing accumulation of toxic Aβ and enhancing the ability of nematodes to resist oxidative stress. Thus, EDVAE has potential to be an effective treatment to relieve the symptoms of AD., (Copyright © 2021. Published by Elsevier B.V.)

Periosteum is essential for bone regeneration and damage repair in mammals. Most species of deer family (Cervidae) develop two kinds of special periosteum, antler periosteum and pedicle periosteum, both supporting the complete regeneration of antler. Antler is the bone organ with the fastest growth rate in mammals. Along with the fast growth of antler, its external tissues such as blood vessels, nerves and the covering skin also grow rapidly. Currently, it is still unclear whether antler periosteum contributes to the fast growth of antler and how. It is also unclear why the regenerative capacity of antler periosteum is weaker than that of pedicle periosteum. In this study, the in vitro culture system for antler periosteal cells (AnPC) was constructed for the first time using the mid-beam antler periostea during antler fast-growth period. According to our results, the cultured AnPC expressed classical MSC markers, consistent with the pedicle periosteal stem cells (PPSC). However, the fluorescence intensities of the MSC markers on AnPC were significantly weaker than those on PPSC. In addition, AnPC showed much lower proliferation rates than PPSC. The proliferation rates of the AnPC also gradually decreased after successive passages, while the proliferation rates of the pedicle periosteal stem cells remained unchanged. These findings may partially explain the weaker regenerative capacity of antler periosteum. Further comparative global gene analysis revealed clearly the different gene expressed patterns between AnPC and PPSC. AnPC may mainly function on promoting angiogenesis, nerve growth and intramembrane bone formation during antler regeneration, whereas PPSC may primarily be involved in androgen signaling receptor pathway and PI3K-Akt signaling pathway and function on maintaining stem cell renewal., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

Land modified for human use alters matrix shape and composition and is a leading contributor to global biodiversity loss. It can also play a key role in facilitating range expansion and ecosystem invasion by anthrophilic species, as it can alter food abundance and distribution while also influencing predation risk; the relative roles of these processes are key to habitat selection theory. We researched these relative influences by examining human footprint, natural habitat, and predator occurrence on seasonal habitat selection by range-expanding boreal white-tailed deer (Odocoileus virginianus) in the oil sands of western Canada. We hypothesized that polygonal industrial features (e.g. cutblocks, well sites) drive deer distributions as sources of early seral forage, while linear features (e.g. roads, trails, and seismic lines) and habitat associated with predators are avoided by deer. We developed seasonal 2nd -order resource selection models from three years of deer GPS-telemetry data, a camera-trap-based model of predator occurrence, and landscape spatial data to weigh evidence for six competing hypotheses. Deer habitat selection was best explained by the combination of polygonal and linear features, intact deciduous forest, and wolf (Canis lupus) occurrence. Deer strongly selected for linear features such as roads and trails, despite a potential increased risk of wolf encounters. Linear features may attract deer by providing high density forage opportunity in heavily exploited landscapes, facilitating expansion into the boreal north., (© 2022. The Author(s).)

Wild animal immobilization often requires high doses of α2-adrenoceptor agonists. Despite their desired sedative and analgetic effects, well-recognized cardiovascular side effects, such as hypertension and bradycardia, remain a major concern. We compared the effect of two medetomidine doses on intra-arterial blood pressure and heart rate in 13 captive, female red deer (Cervus elaphus) immobilized during winter. Each animal was randomly assigned to receive either 80 µg/kg (group L) or 100 µg/kg (group H) medetomidine, combined with 3 mg/kg tiletamine-zolazepam administered intramuscularly. Changes in cardiovascular variables over time and differences between the groups were analyzed using linear mixed-effect models. Induction time was faster in group L compared with group H; recovery time did not differ between groups. Initially, the arterial blood pressure was higher in group H compared with group L, but differences between groups diminished during anesthesia. Moreover, the decline in arterial blood pressure in group H was more rapid. Heart rate was significantly lower in group L, but bradycardia was not observed. The higher medetomidine dose did not reduce induction time, and initial hypertension was reduced by administering the lower dose. Therefore, although the sample size was small and, thus, the significance of results might be limited, we suggest using 80 µg/kg instead of 100 µg/kg medetomidine when combined with 3 mg/kg tiletamine-zolazepam for the immobilization of female red deer., (© Wildlife Disease Association 2022.)

Background: The alternative prey hypothesis describes the mechanism for apparent competition whereby the mortality of the secondary prey species increases (and population size decreases decreases) by the increased predation by the shared predator if the population size of the primary prey decreases. Apparent competition is a process where the abundance of two co-existing prey species are negatively associated because they share a mutual predator, which negatively affects the abundance of both prey Here, we examined whether alternative prey and/or apparent competition hypothesis can explain the population dynamics and reproductive output of the secondary prey, wild forest reindeer (Rangifer tarandus fennicus) in Finland, in a predator-prey community in which moose (Alces alces) is the primary prey and the wolf (Canis lupus) is the generalist predator., Methods: We examined a 22-year time series (1996-2017) to determine how the population size and the calf/female ratio of wild forest reindeer in Eastern Finland were related to the abundances of wolf and moose. Only moose population size was regulated by hunting. Summer predation of wolves on reindeer focuses on calves. We used least squares regression (GLS) models (for handling autocorrelated error structures and resulting pseudo-R2s) and generalized linear mixed (GLMs) models (for avoidance of negative predictions) to determine the relationships between abundances. We performed linear and general linear models for the calf/female ratio of reindeer., Results and Synthesis: The trends in reindeer population size and moose abundance were almost identical: an increase during the first years and then a decrease until the last years of our study period. Wolf population size in turn did not show long-term trends. Change in reindeer population size between consecutive winters was related positively to the calf/female ratio. The calf/female ratio was negatively related to wolf population size, but the reindeer population size was related to the wolf population only when moose abundance was entered as another independent variable. The wolf population was not related to moose abundance even though it is likely to consist the majority of the prey biomass. Because reindeer and moose populations were positively associated, our results seemed to support the alternative prey hypothesis more than the apparent competition hypothesis. However, these two hypotheses are not mutually exclusive and the primary mechanism is difficult to distinguish as the system is heavily managed by moose hunting. The recovery of wild forest reindeer in eastern Finland probably requires ecosystem management involving both habitat restoration and control of species abundances., Competing Interests: The authors have declared that no competing interests exist.

This study aimed to compare the fecal microbiome and antimicrobial resistance between captive and free-range sika deer with the same exposure to antibiotic anthelmintics. The taxonomic differences mainly involved significant changes in the dominant phyla, genera, and species. Linear discriminant analysis effect size (LEfSe) analysis revealed that 22 taxa were significantly different between the two groups. The KEGG analysis showed that the fecal microbiome metabolic function, and all level 2 categories in metabolism had higher abundance in the free-range deer. Based on the carbohydrate-active enzyme (CAZy) database analysis, glycoside hydrolases and carbohydrate-binding modules showed remarkable differences between the two groups. Regarding antibiotic resistance, tet Q and lnu C dominated the antibiotic resistance ontology (ARO) terms, and tetracycline and lincosamide resistance dominated the antimicrobial resistance patterns. Furthermore, the lnu C, Erm F, and tet W/N/W AROs and lincosamide resistance showed higher abundance in the captive deer, suggesting that captivity may yield more serious resistance issues because of the differences in greenfeed diet, breeding density, and/or housing environment. The results also revealed important associations between the phylum Proteobacteria , genus Prevotella , and major antibiotic resistance genes. Although the present study was a pilot study with a limited sample size that was insufficient control for some potential factors, it serves as the metagenomic study on the microbial communities and antimicrobial resistance in sika deer. IMPORTANCE We used a metagenomic approach to investigate whether and how captive and free-range impact the microbial communities and antimicrobial resistance in sika deer. The results provide solid evidence of the significant impacts on the microbial composition and function in captive and free-range sika deer. Interestingly, although the sika deer had the same exposure to antibiotic anthelmintics, the antimicrobial resistances were affected by the breeding environment.

Steroid synthesis and production in ruminant uterus is not obvious, especially in seasonally reproduced. We compared steroid production by investigating enzymes involved in red deer uterine steroid metabolism in reproductive seasons. Blood and uteri (endometrium and myometrium) were collected post mortem from hinds on 4th day (N = 8), 13th day of the cycle (N = 8), anestrus (N = 8) and pregnancy (N = 8). The expression of cytochrome P450 aromatase (P450), 3 -beta-hydroxysteroid dehydrogenase (3β-HSD), 17 -beta-hydroxysteroid dehydrogenase (17β-HSD), aldo-keto reductase family 1 C1 (AKR1C1), estrogen receptor alpha (ERα), and progesterone receptors (PRs), were analyzed using real-time-PCR and Western Blotting. Plasma samples were assayed for 17-beta-estradiol (E2), progesterone (P4), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T4) concentrations by EIA. Hinds at the beginning of the estrous cycle, mainly in endometrium, were characterized by a high mRNA expression of 3β-HSD, AKR1C1, PRs and ERα, contrary to the expression in myometrium during pregnancy (P < 0.05). For P4, E2, and FSH, concentration was the highest during the 13th day of the estrous cycle (P < 0.05). Uterine steroid production and output in hinds as a representative seasonally reproduced ruminant occurred mainly during the estrous cycle and sustained in anestrus., (© 2021. The Author(s).)

It is commonly understood that dietary nutrition will influence the composition and function of the animal gut microbiome. However, the transmission of organisms from the diet-source microbiome to the animal gut microbiome in the natural environment remains poorly understood, and elucidating this process may help in understanding the evolution of herbivores and plant defenses. Here, we investigated diet-source microbiome transmission across a range of herbivores (insects and mammals) living in both captive and wild environments. We discovered a host bias among cohabitating herbivores (leaf-eating insects and deer), where a significant portion of the herbivorous insect gut microbiome may originate from the diet, while in deer, only a tiny fraction of the gut microbiome is of dietary origin. We speculated that the putative difference in the oxygenation level in the host digestion systems would lead to these host biases in plant-source (diet) microbiome transmission due to the oxygenation living condition of the dietary plant's symbiotic microbiome. IMPORTANCE We discovered a host bias among cohabitating herbivores (leaf-eating insects and deer), where a significant portion of the herbivorous insect gut microbiome may originate from the diet, while in deer, only a tiny fraction of the gut microbiome is of dietary origin. We speculated that the putative difference in the oxygenation level in the host digestion systems would lead to these host biases in plant-source (diet) microbiome transmission due to the oxygenation living condition of the dietary plant's symbiotic microbiome. This study shed new light on the coevolution of herbivory and plant defense.

There is a growing interest on the potential interplay between weather, habitat, and interspecific competition on population dynamics of wild herbivores. Favorable environmental conditions may buffer the negative effects of competition; conversely, competition may be expected to be stronger under harsh environmental conditions. We investigated relationships between competitor abundance, weather, and habitat cover on density and local distribution of a medium-sized herbivore, the roe deer Capreolus capreolus, as well as its spatial overlap with fallow deer Dama dama in a Mediterranean protected area. Over 11 years (2007-2017), roe deer density was not affected by spring-summer rainfall in the previous year and decreased with increasing density of fallow deer in the previous year. Hence, over the considered temporal scale, results supported a major role of competition over weather in influencing population trends of roe deer. At a finer spatial scale, roe deer occupancy was negatively affected by local abundance of fallow deer, especially in "poorer" habitats. We found a slight support for a positive effect of fallow deer density on interspecific spatial overlap. Moreover, fine-scale spatial overlap between deer species increased with decreasing rainfall in spring-summer. Fallow deer were introduced to our study area in historical times and their role as superior competitors over roe deer has been found also in other study areas. We suggest a potential role of harsh weather conditions during the growing season of vegetation (i.e. scarce rainfall) in triggering the potential for ecological overlap, emphasizing the negative effects of interspecific competition., (© 2020 The Authors. Integrative Zoology published by International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

The hand-held infrared thermal imaging sensor was used to measure the body temperature of deer. The measurement farm was located in Yunlin County. The eyes of 6 male deer and 3 female deer were measured. The distance between the surroundings and the infrared thermal imaging sensor is about 150 cm. There are 36 points measured. The average value is 38.54 ± 0.68°C. In addition, considering that the average length of the deer stall is about 300 cm, the temperature around the eyes of the doe's eyes is measured at a distance of about 300 cm for 3 deer from the infrared thermal imaging sensor. Total of 5 points are measured, and the average is 37.92 ± 1.40°C. The average rectal temperature of the doe was 38.1°C and the difference was 0.18°C. The temperature around the anus of 4 female deer was measured at 4 points. The average value was 37.85 ± 1.40°C, which was 0.25°C different from the average rectal temperature of 38.1°C. The results showed that the temperature around the eyes and the temperature around the anus are closer to the actual deer's anal temperature. [ABSTRACT FROM AUTHOR]

Embryonic diapause in mammals leads to a reversible developmental arrest. While completely halted in many species, European roe deer ( Capreolus capreolus ) embryos display a continuous deceleration of proliferation. During a 4-mo period, the cell doubling time is 2 to 3 wk. During this period, the preimplantation blastocyst reaches a diameter of 4 mm, after which it resumes a fast developmental pace to subsequently implant. The mechanisms regulating this notable deceleration and reacceleration upon developmental resumption are unclear. We propose that amino acids of maternal origin drive the embryonic developmental pace. A pronounced change in the abundance of uterine fluid mTORC1-activating amino acids coincided with an increase in embryonic mTORC1 activity prior to the resumption of development. Concurrently, genes related to the glycolytic and phosphate pentose pathway, the TCA cycle, and one carbon metabolism were up-regulated. Furthermore, the uterine luminal epithelial transcriptome indicated increased estradiol-17β signaling, which likely regulates the endometrial secretions adapting to the embryonic needs. While mTORC1 was predicted to be inactive during diapause, the residual embryonic mTORC2 activity may indicate its involvement in maintaining the low yet continuous proliferation rate during diapause. Collectively, we emphasize the role of nutrient signaling in preimplantation embryo development. We propose selective mTORC1 inhibition via uterine catecholestrogens and let-7 as a mechanism regulating slow stem cell cycle progression., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

Defaunation is a global threat to biodiversity that can be counteracted through trophic rewilding, a restoration strategy that promotes self-regulating ecosystems through active reintroductions or passive management. In order to estimate success in restoration initiatives, progress of the rewilding projects is measured and monitored. However, a spatially explicit understanding of rewilding and rewilding potential in a rewilding site has been absent so far. We present a novel approach for monitoring rewilding progress that focuses on a spatially explicit estimate of progress and ecological integrity within rewilding initiatives. This framework uses habitat classification of the site and tracking data of the reintroduced animals, to model their habitat selection. Through this we measure and map realized and potential rewilding. We operationalize the framework in an ongoing rewilding project in the Iberá Wetlands, Corrientes, Argentina. The majority of areas (76%) predicted to be occupied by reintroduced fauna were only predicted to be selected by one species. Of the four species in the rewilding project, only the giant anteater (Myrmecophaga tridactyla) filled the majority of its potential distribution, whereas pampas deer (Ozotoceros bezoarticus), collared peccary (Pecari tajacu) and lowland tapir (Tapirus terrestris) filled less than 23% of theirs. After rewilding we found a 10% increase in the proportion of the study area with high ecological integrity. Through this case study, we showed that this framework can be used to assess the spatial progress of a rewilding site. By incorporating wildlife tracking and satellite-based remote sensing, we are integrating a spatial component to monitoring of rewilding projects that should lead to more detailed understanding of the progress of rewilding. Applying this framework would facilitate decision-making for practitioners and inform species management plans., Competing Interests: The authors have declared that no competing interests exist.

Rumen content stratification and the degree of dissociation of particle and fluid retention in the reticulorumen differ between 'moose-type' and 'cattle-type' ruminant species. These differences are not strictly linked to diet, except for a seeming limitation of 'moose-type' ruminants to a browsing niche. Nevertheless, these differences can be plausibly linked to other observed differences in ruminants, such as the intraruminal papillation pattern, or the size of the omasum. However, many of the corresponding measures are still only available for a restricted number of species. Here, we investigated the dry matter (i.e., the inverse of the moisture) concentration in forestomach contents of 10 blackbuck (Antilope cervicapra) and 7 Arabian sand gazelle (Gazella subgutturosa marica), and quantified the rumen papillation pattern. The blackbucks had distinct rumen contents stratification, with more moisture in ventral than in dorsal contents (difference 3.6% units, P < 0.001), whereas this difference was much less pronounced in the sand gazelles (0.6% units, P = 0.227). While reticulum contents were particularly moist in both species, omasum contents were particularly dry in sand gazelles, but did not differ in moisture from rumen contents in the blackbuck. This species is an outlier among ruminants due to its extremely small omasum. The intraruminal papillation pattern did not differ between blackbucks and sand gazelles and showed a surface enlargement factor (SEF) in the dorsal rumen of 27-28% of the SEF in the Atrium ruminis. Compared to data on digesta retention in the same species, the findings are in line with the overall concept of a high fluid throughput causing a distinct stratification of rumen contents and intraruminal papillation, and necessitating a large omasum for fluid re-absorption. However, the data also show that individual species may not correspond to all the assumptions of the concept, suggesting taxon-specific differences between species. Reasons for these differences cannot be linked to a dietary grass-browse spectrum, but may lie in evolutionary contingency., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Many animals restrict their movements to a characteristic home range. This constrained pattern of space use is thought to result from the foraging benefits of memorizing the locations and quality of heterogeneously distributed resources. However, due to the confounding effects of sensory perception, the role of memory in home-range movement behavior lacks definitive evidence in the wild. Here, we analyze the foraging decisions of a large mammal during a field resource manipulation experiment designed to disentangle the effects of memory and perception. We parametrize a mechanistic model of spatial transitions using experimental data to quantify the cognitive processes underlying animal foraging behavior and to predict how individuals respond to resource heterogeneity in space and time. We demonstrate that roe deer ( Capreolus capreolus ) rely on memory, not perception, to track the spatiotemporal dynamics of resources within their home range. Roe deer foraging decisions were primarily based on recent experience (half-lives of 0.9 and 5.6 d for attribute and spatial memory, respectively), enabling them to adapt to sudden changes in resource availability. The proposed memory-based model was able to both quantify the cognitive processes underlying roe deer behavior and accurately predict how they shifted resource use during the experiment. Our study highlights the fact that animal foraging decisions are based on incomplete information on the locations of available resources, a factor that is critical to developing accurate predictions of animal spatial behavior but is typically not accounted for in analyses of animal movement in the wild., Competing Interests: The authors declare no competing interest.

Ungulates in alpine ecosystems are constrained by winter harshness through resource limitation and direct mortality from weather extremes. However, little empirical evidence has definitively established how current climate change and other anthropogenic modifications of resource availability affect ungulate winter distribution, especially at their range limits. Here, we used a combination of historical (1997-2002) and contemporary (2012-2015) Eurasian roe deer (Capreolus capreolus) relocation datasets that span changes in snowpack characteristics and two levels of supplemental feeding to compare and forecast probability of space use at the species' altitudinal range limit. Scarcer snow cover in the contemporary period interacted with the augmented feeding site distribution to increase the elevation of winter range limits, and we predict this trend will continue under climate change. Moreover, roe deer have shifted from historically using feeding sites primarily under deep snow conditions to contemporarily using them under a wider range of snow conditions as their availability has increased. Combined with scarcer snow cover during December, January, and April, this trend has reduced inter-annual variability in space use patterns in these months. These spatial responses to climate- and artificial resource-provisioning shifts evidence the importance of these changing factors in shaping large herbivore spatial distribution and, consequently, ecosystem dynamics.

Deer antlers are the only mammalian organs that can fully regenerate, which relies on pedicle periosteum (PP). Interestingly during the growing phase, antlers themselves can regenerate partially lost antler tissue. However, what tissue type in the growing antlers fulfills this role is not known. Following antler removal during the growing phase, a "second" antler regenerates from the stump. In this study, the "second" antler growing from the cut antler base (AB) was examined in both red and sika deer. The results showed that all regenerating antlers were formed from the peripheral edge of the AB, where the antler periosteum (AnP) is located. The growth center showed a clear demarcation from the AB bone in red deer. Therefore, it is highly likely that AnP is the tissue that possesses the potential. Factors that might affect this potential were explored and the main factor was found to be AB calcification, which was controlled by rising androgens. Thus, the ultimate antler regeneration potential of the AnP was assessed through castration and repeated antler removal. The results demonstrated that the regeneration potential of AnP was somewhat limited and inferior to that of the PP. The ability of AnP to achieve partial regeneration may be evolutionarily conserved, as the regeneration of partially lost antlers within the season is secured; whereas, with PP, a new set of antlers in the next season is guaranteed. This two-level mechanism may signify how evolutionarily important it is for deer to possess reasonably intact antlers., (© 2021 Wiley Periodicals LLC.)

In vertebrates, offspring survival often decreases with increasing maternal age. While many studies have reported a decline in fitness-related traits of offspring with increasing maternal age, the study of senescence in maternal effect through age-specific changes in offspring physiological condition is still at its infancy. We assessed the influence of maternal age and body mass on offspring physiological condition in two populations of roe deer (Capreolus capreolus) subjected to markedly different environmental conditions. We measured seven markers to index body condition and characterize the immune profile in 86 fawns which became recently independent of their known-aged mothers. We did not find striking effects of maternal age on offspring physiological condition measured at 8 months of age. This absence of evidence for senescence in maternal effects is likely due to the strong viability selection observed in the very first months of life in this species. Offspring physiological condition was, on the other hand, positively influenced by maternal body mass. Between-population differences in environmental conditions experienced by fawns also influenced their average body condition and immune phenotype. Fawns facing food limitation displayed lower values in some markers of body condition (body mass and haemoglobin levels) than those living in good quality habitat. They also allocated preferentially to humoral immunity, contrary to those living in good conditions, which allocated more to cellular response. These results shed a new light on the eco-physiological pathways mediating the relationship between mother's mass and offspring condition., (© 2021 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.)

Copper (Cu), iron (Fe), and zinc (Zn) are essential trace minerals for the reproduction, growth, and immunity of mammalian herbivore populations. We examined the relationships between Cu, Fe, and Zn in soils, common plants, and hepatic stores of two wild herbivores to assess the effects of weather, sex, and population density on the transfer of trace minerals from soils to mammals during the growing season. Soils, grasses, woody browse, hispid cotton rats (Sigmodon hispidus), and white-tailed deer (Odocoileus virginianus) were sampled across 19 sites. Concentrations of Cu, Fe, and Zn in grasses and browse species were not correlated with concentrations of those minerals in soils sampled from the same areas. Leaves of woody browse were higher in Cu, lower in Fe, and similar in Zn when compared with grasses. Available concentrations of soils were positively related to liver Cu and Zn in hispid cotton rats, which was consistent with the short lives and high productivity of these small mammals that rely on grass seed heads. Interactions between soil concentrations and weather also affected liver Cu and Fe in deer, which reflected the greater complexity of trophic transfers in large, long-lived, browsing herbivores. Population density was correlated with liver concentrations of Cu, Fe, and Zn in hispid cotton rats, and concentrations of Cu and Fe in deer. Liver Cu was < 5 mg/kg wet weight in at least 5% of animals at two of eight sites for hispid cotton rats and < 3.8 mg/kg wet weight in at least 5% of animals at three of 12 sites for deer, which could indicate regional limitation of Cu for populations of mammalian herbivores. Our data indicate that supplies of trace minerals may contribute to density dependence of herbivore populations. Local population density may therefore influence the prevalence of deficiency states and disease outbreak that exacerbate population cycles in wild mammals., Competing Interests: The authors have declared that no competing interests exist.

It is unknown how ungulate physiological responses to environmental perturbation influence overall population demographics. Moreover, neonatal physiological responses remain poorly studied despite the importance of neonatal survival to population growth. Glucocorticoid (GC) hormones potentially facilitate critical physiological and behavioral responses to environmental perturbations. However, elevated GC concentrations over time may compromise body condition and indirectly reduce survival. We evaluated baseline salivary cortisol (CORT; a primary GC in mammals) concentrations in 19 wild neonatal white-tailed deer (Odocoileus virginianus) in a northern (NS) and southern (SS) area in Pennsylvania. After ranking survival models consisting of variables hypothesized to influence neonate survival (i.e. weight, sex), the probability of neonate survival was best explained by CORT concentrations, where elevated CORT concentrations were associated with reduced survival probability to 12 weeks of age. Cortisol concentrations were greater in the SS where predation rates and predator densities were lower. As the first evaluation of baseline CORT concentrations in an ungulate neonate to our knowledge, this is also the first study to demonstrate CORT concentrations are negatively associated with ungulate survival at any life stage. Glucocorticoid hormones could provide a framework in which to better understand susceptibility to mortality in neonatal white-tailed deer., (© 2020 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

During the rutting season, stag semen is accompanied by a sticky, dense secretion called yellow fraction (YF). There is little information about the role, biology, physiology, and most importantly, the composition of this fluid. The aim of this study was to isolate and identify zinc ions (ZnBPs) and heparin binding proteins (HBPs) from YF of the red deer (Cervus elaphus L.). Using liquid chromatography, the presence of 6 fractions of ZnBPs (71, 65, 55, 16, 14 and 12 kDa) and 22 fractions of HBPs (163, 140, 96, 78, 71, 65, 55, 49, 33, 31, 26, 25, 24, 22, 18, 16, 13, 12, 11, 10, 9 and 8 kDa) in YF proteome was demonstrated. By means of two-dimensional electrophoreses and MALDI-TOF/TOF mass spectrometry some of them were then identified. Amongst ZnBPs the following were identified: glutaminyl-peptide cyclotransferase, inhibitor of carbonic anhydrase-like, potassium voltage-gated channel subfamily E member 2, WD repeat-containing protein 38 isoform X4. Amongst the HBPs metalloproteinase inhibitor 2 (TIMP2), seminal plasma glycoprotein PSP-I and adseverin (scinderin) were identified. Identifying all ZnBPs and HBPs present in YF may broaden up-to-date knowledge concerning the biology, physiology and preservation of red deer semen., (Copyright© by the Polish Academy of Sciences.)

5-Aza-2'-deoxycytidine (5-Aza-dC), an inhibitor of DNA methyltransferases, is an effective treatment for various cancers and has improved the development rate of cloned embryos. Previous studies have reported the effect of 5-Aza-dC on fibroblasts; however, the mechanism whereby 5-Aza-dC affects sika deer granulosa cells and hormone secretion is presently unknown. Here, we showed that the cell cycle after treatment with different doses of 5-Aza-dC was significantly altered. The number of cells in the S phase was significantly increased in response to a concentration of 0.1 μM 5-Aza-dC. The rate of apoptosis was increased when cells were treated with 0.1 μM and 5 μM 5-Aza-dC. We showed that the protein level of H3K9me2 was significantly decreased in response to 5-Aza-dC. The activity levels of DNA methyltransferase were reduced by a moderate dose of 5-Aza-dC. Furthermore, the secretion of E 2 and P 4 was influenced by different doses of 5-Aza-dC. Our study suggested that 5-Aza-dC affected hormone secretion in sika deer granulosa cells through cell development and epigenetic regulation. The findings of this study lay the foundation for further epigenetic studies in sika deer., (© 2020 Wiley-VCH GmbH.)

Objective: In this paper we aim to provide baseline data and model the changes of Ca, P and Mg throughout life in the mandibular bone, enamel and dentin of red (Cervus elaphus) and fallow deer (Dama dama) in Mediterranean ecosystems., Design: Through a cross-sectional study of cervids from 1.5 to 20 yrs old, hunted between 1990 and 1997, we apply generalized additive models (GAMs) with data from scanning-electron-microscope with energy-dispersive X-ray (FESEM-EDX) and inductively coupled plasma-mass spectrometry (ICP-MS) analyses., Results: The mineral content varied in a similar range to that reported for other ruminants. However, we detected lower Ca content values, while more similar results were obtained for P and Mg contents, which led to relatively lower Ca/P ratios and higher Ca/Mg in our deer at that time. A significantly lesser pattern of decreasing mineral content with aging was detected in the fallow deer males, similarities were found between the sexes, and significantly less resistance to demineralization was observed in dentin compared to bone. We discuss how the basic macromineral elements involved in the biomineralization process vary with age throughout life depending on deer species, sex and hard tissues., Conclusion: Allowing for possible inferences of differential changes in the mineralization state at the main stages in life history, our methodological approach opens up new possibilities in zooarchaeological, paleontological, and wildlife research., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In the last decades, climate change has caused an increase in mean temperatures and a reduction in average rainfall in southern Europe, which is expected to reduce resource availability for herbivores. Resource availability can influence animals' physical condition and population growth. However, much less is known on its effects on reproductive performance and sexual selection. In this study, we assessed the impact of three environmental factors related to climate change (rainfall, temperature and vegetation index) on Iberian red deer Cervus elaphus hispanicus reproductive timing and sexual behaviour, and their effects on the opportunity for sexual selection in the population. We measured rutting phenology as rut peak date, the intensity of male rutting activity as roaring rate, and the opportunity for sexual selection from the distribution of females among harem holding males in Doñana Biological Reserve (Southwest Spain), from data of daily observations collected during the rut over a period of 25 years. For this study period, we found a trend for less raining and hence poorer environmental conditions, which associated with delayed rutting season and decreased rutting intensity, but that appeared to favour a higher degree of polygyny and opportunity for sexual selection, all these relationships being modulated by population density and sex ratio. This study highlights how climate change (mainly rainfall reduction in this area) can alter the conditions for mating and the opportunity for sexual selection in a large terrestrial mammal., Competing Interests: NO authors have competing interests.

The origins of the regenerative nature of antlers, being branched and deciduous apophyseal appendages of frontal bones of cervid artiodactyls, have long been associated with permanent evolutionary precursors. In this study, we provide novel insight into growth modes of evolutionary early antlers. We analysed a total of 34 early antlers affiliated to ten species, including the oldest known, dating from the early and middle Miocene (approx. 18 to 12 million years old) of Europe. Our findings provide empirical data from the fossil record to demonstrate that growth patterns and a regular cycle of necrosis, abscission and regeneration are consistent with data from modern antlers. The diverse histological analyses indicate that primary processes and mechanisms of the modern antler cycle were not gradually acquired during evolution, but were fundamental from the earliest record of antler evolution and, hence, explanations why deer shed antlers have to be rooted in basic histogenetic mechanisms. The previous interpretation that proximal circular protuberances, burrs, are the categorical traits for ephemerality is refuted.

Wildlife disease incidence is increasing, resulting in negative impacts on the economy, biodiversity, and potentially human health. Chronic wasting disease (CWD) is a fatal, transmissible spongiform encephalopathy of cervids (wild and captive) which continues to spread geographically resulting in exposure to potential new host species. The disease agent (PrP CWD ) is a misfolded conformer of the cellular prion protein (PrP C ). In Canada, the disease is endemic in Alberta and Saskatchewan, affecting mule and white-tail deer, with lesser impact on elk and moose. As the disease continues to expand, additional wild ungulate species including bison, bighorn sheep, mountain goat, and pronghorn antelope may be exposed. To better understand the species-barrier, we reviewed the current literature on taxa naturally or experimentally exposed to CWD to identify susceptible and resistant species. We created a phylogeny of these taxa using cytochrome B and found that CWD susceptibility followed the species phylogeny. Using this phylogeny we estimated the probability of CWD susceptibility for wild ungulate species. We then compared PrP C amino acid polymorphisms among these species to identify which sites segregated between susceptible and resistant species. We identified sites that were significantly associated with susceptibility, but they were not fully discriminating. Finally, we sequenced Prnp from 578 wild ungulates to further evaluate their potential susceptibility. Together, these data suggest the host-range for CWD will potentially include pronghorn, mountain goat and bighorn sheep, but bison are likely to be more resistant. These findings highlight the need for monitoring potentially susceptible species as CWD continues to expand.

Chronic wasting disease is a fatal, horizontally transmissible prion disease of cervid species that has been reported in free-ranging and farmed animals in North America, Scandinavia, and Korea. Like other prion diseases, CWD susceptibility is partly dependent on the sequence of the prion protein encoded by the host's PRNP gene; it is unknown if variations in PRNP have any meaningful effects on other aspects of health. Conventional diagnosis of CWD relies on ELISA or IHC testing of samples collected post-mortem, with recent efforts focused on antemortem testing approaches. We report on the conclusions of a study evaluating the role of antemortem testing of rectal biopsies collected from over 570 elk in a privately managed herd, and the results of both an amplification assay (RT-QuIC) and conventional IHC among animals with a several PRNP genotypes. Links between PRNP genotype and potential markers of evolutionary fitness, including pregnancy rates, body condition, and annual return rates were also examined. We found that the RT-QuIC assay identified significantly more CWD positive animals than conventional IHC across the course of the study, and was less affected by factors known to influence IHC sensitivity - including follicle count and PRNP genotype. We also found that several evolutionary markers of fitness were not adversely correlated with specific PRNP genotypes. While the financial burden of the disease in this herd was ultimately unsustainable for the herd owners, our scientific findings and the hurdles encountered will assist future CWD management strategies in both wild and farmed elk and deer.