Explore the vast range of titles available.

Large mammalian herbivores not only depend on plant communities for their existence but cause major changes in plant community composition and structure. These changes have direct consequences for ecosystem processes, but recent studies of ungulate-ecosystem relations show widely divergent ungulate effects in different ecosystems. We reviewed studies of ungulate effects on plant community composition to gain insight into potential mechanisms of ungulate-induced changes in both community composition and ecosystem processes. Our analysis of these studies is based on the premise that the effect ungulates exert on plant communities depends on the balance between (1) feeding selectivity of herbivores (i.e., degree to which different plant species or ecotypes experience different levels of tissue loss), and (2) differences among plant species in their ability to recover from tissue loss. A large number of studies clearly show that selective ungulate herbivory leads to the dominance of unpalatable, chemically defended plant species in communities. However, many studies have also demonstrated that intensive long-term herbivory does not lead to the invasion of unpalatable species into the community, and can even increase the dominance of highly palatable species. Our review indicates that high levels of nutrient inputs or recycling and an intermittent temporal pattern of herbivory (often due to migration) are key factors increasing the regrowth capacity of palatable species and hence maintaining their dominance in plant communities supporting abundant herbivores. Key factors limiting ungulate foraging selectivity, again limiting herbivore-induced dominance of slow-growing, unpalatable species, include herding behavior, early growing season and postfire herbivory, asynchronous phenology of palatable versus unpalatable species, and low relative abundance of unpalatable species. Our review indicates differences among ecosystems in the role played by ungulate herbivory result from the relative strength of these factors enhancing plant tolerance to herbivory and limiting foraging selectivity. Anthropogenic changes in these factors (e.g., alteration of migration patterns) therefore have the potential to significantly alter the effects of ungulates on plant communities and ecosystem processes.

Within large grassland ecosystems, climatic and topographic gradients are considered the primary controls of soil processes. Ungulates also can influence soil dynamics; however the relative contribution of large herbivores to controlling grassland soil processes remains largely unknown. In this study, we compared the effects of native migratory ungulates and variable site (\"landscape\") conditions, caused by combined climatic and topographic variability, on grassland of the northern winter range of Yellowstone National Park by determining soil C and N dynamics inside and outside 33-37 yr exclosures at seven diverse sites. Sites included hilltop, slope, and slope bottom positions across a climatic gradient and represented among the driest and wettest grasslands on the northern winter range. We performed two experiments: (1) a 12-mo in situ net N mineralization study and (2) a long-term (62-wk) laboratory incubation to measure potential N mineralization and microbial respiration. Results from the in situ experiment indicated that average net N mineralization among grazed plots (3.8 g N· m-2· yr-1) was double that of fenced, ungrazed plots (1.9 g N· m-2· yr-1). Mean grazer enhancement of net N mineralization across sites (1.9 g N· m-2· yr-1) approached the maximum difference in net N mineralization among fenced plots (2.2 g N· m-2· yr-1), i.e., the greatest landscape effect observed. Furthermore, ungulates substantially increased between-site variation in mineralization; grazed grassland, 1 SD = 2.2 g N· m-2· yr-1, fenced grassland, 1 SD = 2.2 g N· m-2· yr-1. In the long-term incubation, potential microbial respiration and net N mineralization were positively related to total soil C and N content, respectively. There was greater variation in potential respiration and net N mineralization early in the incubation, when labile material was processed, compared to late in the incubation, when more recalcitrant substrate was processed, suggesting that between-site variation in labile organic matter was greater than that of recalcitrant material. Herbivores improved the organic matter quality of soil, increasing the labile fractions and reducing the recalcitrant fractions. Grazers reduced C respired/N mineralized ratios, an index of microbial N immobilization, by an average of 21%. However, the largest landscape influence on the immobilization index was 13-fold greater than the grazer effect. Given that the greatest landscape influence on in situ net mineralization (2.2 g N· m-2· yr-1) was similar to the average grazer impact on that rate (1.9 g N· m-2· yr-1), we hypothesize that the landscape effect on field N availability was primarily caused by variation in microbial immobilization, while the grazing effect was primarily due to stimulation of gross mineralization. These results indicate that the relative importance of ungulates in controlling soil N cycling may be more important than previously suspected for grasslands supporting large herds of migratory ungulates, and that the dominant mechanisms underlying the landscape and ungulate influences on soil mineral fluxes may differ.

We measured faecal cortisol metabolites of a free-ranging riparian population of red deer to investigate potential effects of season, ambient temperature, precipitations and water level on the annual secretion pattern. Individuals may cope with environmental challenges through the secretion of stress hormones (glucocorticoids) which allows the integration of environmental change and life history traits by means of an adaptive feedback mechanism. Adaptations regard cyclic day-to-day activities, short-term environmental stressors or long-term ecological pressures. We detected a clear seasonal pattern of glucocorticoid metabolites secretion, with higher levels in winter and lower levels in summer. The model relating glucocorticoids secretion to minimum ambient temperature was the best fit to our dataset, although the observed pattern might as well be due to declining nutritional intake and reduction of metabolic rate in the cold season. We observed an improvement of the fit when stochastic events (flash flood) were included in the model, and discussed their role as potential contingent environmental stressors.

The pregnancy-associated glycoproteins (PAGs) are structurally related to the pepsins, thought to be restricted to the hooved (ungulate) mammals and characterized by being expressed specifically in the outer epithelial cell layer (chorion/trophectoderm) of the placenta. At least some PAGs are catalytically inactive as proteinases, although each appears to possess a cleft capable of binding peptides. By cloning expressed genes from ovine and bovine placental cDNA libraries, by Southern genomic blotting, by screening genomic libraries, and by using PCR to amplify portions of PAG genes from genomic DNA, we estimate that cattle, sheep, and most probably all ruminant Artiodactyla possess many, possibly 100 or more, PAG genes, many of which are placentally expressed. The PAGs are highly diverse in sequence, with regions of hypervariability confined largely to surface-exposed loops. Nonsynonymous (replacement) mutations in the regions of the genes coding for these hypervariable loop segments have accumulated at a higher rate than synonymous (silent) mutations. Construction of distance phylograms, based on comparisons of PAG and related aspartic proteinase amino acid sequences, suggests that much diversification of the PAG genes occurred after the divergence of the Artiodactyla and Perissodactyla, but that at least one gene is represented outside the hooved species. The results also suggest that positive selection of duplicated genes has acted to provide considerable functional diversity among the PAGs, whose presence at the interface between the placenta and endometrium and in the maternal circulation indicates involvement in fetal-maternal interactions

Norway spruce is a wide-spread food resource and its utilisable biomass exceeds the needs of herbivores. Needles seem to be a generally ignored food component in temperate forests that is consumed only when there are no better food sources. It is used especially during winters with deep snow cover. The aim of this study was to test presumption of needles as nutritive poor component of ungulate diets through botanical diet analyses and chemical nutrition estimation (content of crude protein and metabolizable energy volume in faeces) and elaborate the calibration curve on indirect estimation of quality food resources for ungulates in environment (NIRS needle content in faeces). High content of spruce needles corresponded well with a low quality winter diet of wild ungulates and may reflect animal nutritional constraints. As a consequence, the content of spruce needles may be used as an easy index of animal performance in a particular environment in forested area with coniferous forests in temperate zone. Needle content can be determined from the faeces by near infrared spectrophotometer and this easy technique can be recommended as indicator of the food resources quality for ungulates.

Why does it benefit some male and female animals to live separately?Sexual segregation, wherein the sexes of a species live apart for long periods of time, has far-reaching consequences for the ecology, behavior, and conservation of hooved mammals, which are called ungulates. Award-winning researcher R. Terry Bowyer has spent the past four decades unravelling the causes and consequences of this perplexing phenomenon by studying ungulates and the large carnivores that prey upon them. In Sexual Segregation in Ungulates, Bowyer's critical, thought-provoking approach helps resolve long-standing disagreements concerning sexual segregation and offers future pathways for species and habitat conservation. He highlights important elements of the natural history of wild ungulate species, including bighorn sheep and elk. He then uses this perspective to frame and test hypotheses illuminating the motivations behind sexual segregation. He investigates the role of sexual segregation in mechanisms underpinning ungulate mating systems, sexual dimorphism, paternal behavior, and population dynamics. Bowyer's research spans ecosystems from deserts to the Arctic and involves most species of ungulates inhabiting the North American continent. He also provides a timely review of sexual segregation for species of plants and other animals, including humans. Covering definitions, theory, findings, and practical applications of related study, Bowyer describes the behavioral patterns related to sexual segregation, explains how to detect these patterns, and considers the implications of sexual segregation for new approaches to conservation and management of ungulates and other species of wildlife.This book is essential reading for scientists and all those interested in the conservation and management of species, including wildlife professionals, hunters, outdoor enthusiasts, and naturalists.

The objective of this work was to assess the impact of ungulates on the natural regeneration of woods in a model area within the National Nature Reserve (NNR) of Mláčik - by comparing marked specimens within a pair of research areas. Damage to the naturally regenerating woods was analyzed, the impact of damage to height growth, the impact of game species on the development of the number of trees and their species represented within the growth. The measurements began in the autumn 2007, then they were repeated twice a year (spring, when damage caused by ungulates during the winter was surveyed, and in the autumn - for the damage caused during the summer). The saplings found in the NNR Mláčik are: ash, beech, sycamore, elm, fir, and Wild Service Tree. Scattered are aspen, birch and willow. Ash, fir, maple and elm suffer the most damage due to gnawing. As the regeneration of fir saplings occurs only sporadically, this species may be considered the most endangered tree within the reservation. After two years of protection, significant differences were found in the number of fir trees between the open areas in comparison to the enclosed areas. From the degree of damage and significantly reduced numbers one, can ascertain its high attractiveness to the game. Overall, beech is the least damaged species by game, with only a marginal difference recorded between the plots (fenced and unfenced).

Many grazing animals in both terrestrial and aquatic ecosystems form dense herds that maintain the vegetation in their concentration areas at very low statures. Studies of the effects of large ungulates on the structure of grasslands in the Serengeti region of Tanzania and Kenya indicated that some vegetation was arrested in a short form throughout the wet season while other vegetation was only lightly grazed during that season and reached similar heights in fenced and unfenced areas. Biomass concentration, the mass of foliage per unit of canopy volume, was consistently and substantially higher in unfenced plots but the covariation of height and biomass concentration across plots along the Serengeti's habitat gradient indicated that the tendency toward production of a dense, prostrate grazing lawn in ecological time was accentuated by, but was not solely a consequence of, proximal grazing intensity. Transplant garden studies documented intrinsic differences within and between species in traits related to dwarfing. Comparisons of the Serengeti data with information on the foraging of domestic ungulates indicated that individual grazers obtain a foraging advantage by membership in a herd because of the greater forage yield per bite from grazing lawns compared with lightly grazed vegetation. Thus, natural selection at the individual level, acting on both animals and plants to produce coevolution among members of the same trophic web, can regulate such ecosystem processes as energy flow and nutrient cycling, and contribute to species coexistence and the resultant species diversity of communities.

Differential maternal investment in sons and daughters can be accomplished by adjusting the sex ratio of offspring or by investing differentially in individual sons and daughters. In polygynous mammals, such as most ungulates, sons are larger than daughters at the end of the lactation period, and the raising of a son can be more expensive than raising a daughter. After weaning, daughters will provide extra maternal investment by sharing their mothers' home range, and local resource competition probably increases the costs associated with producing a daughter. In some species sons seem to benefit from their mothers' phenotypical superiority through heavier maternal investment before weaning, while daughters can share their mothers' high social rank also after weaning. I suggest from the reviewed literature that local resource competition shapes offspring sex ratios at the population level most clearly when the diet type is browse that is a more defendable resource than graze. It is also probable that differential costs, for example in the form of the subsequent reproductive success and the survival of the mother, are associated with producing sons and daughters are an important selective force modifying sex ratios born to superior and weak females within populations, in addition to a stronger correlation between mothers' quality and the reproductive success of the offspring of one sex. This correlation can be associated also with fitness costs, because the rearing of a weakly competitive offspring may result in the wastage of reproductive effort.