Habitat Selection of Rocky Mountain Elk in a Nonforested Environment

Abstract: Recent expansions by Rocky Mountain elk (Cervus elaphus) into nonforested habitats across the Intermountain West have required managers to reconsider the traditional paradigms of forage and cover as they relate to managing elk and their habitats. We examined seasonal habitat selection patterns of a hunted elk population in a nonforested high-desert region of southwestern Wyoming, USA. We used 35,246 global positioning system locations collected from 33 adult female elk to model probability of use as a function of 6 habitat variables: slope, aspect, elevation, habitat diversity, distance to shrub cover, and distance to road. We developed resource selection probability functions for individual elk, and then we averaged the coefficients to estimate population-level models for summer and winter periods. We used the population-level models to generate predictive maps by assigning pixels across the study area to 1 of 4 use categories (i.e., high, medium-high, medium-low, or low), based on quartiles of the predictions. Model coefficients and predictive maps indicated that elk selected for summer habitats characterized by higher elevations in areas of high vegetative diversity, close to shrub cover, northerly aspects, moderate slopes, and away from roads. Winter habitat selection patterns were similar, except elk shifted to areas with lower elevations and southerly aspects. We validated predictive maps by using 528 locations collected from an independent sample of radiomarked elk (n = 55) and calculating the proportion of locations that occurred in each of the 4 use categories. Together, the high- and medium-high use categories of the summer and winter predictive maps contained 92% and 74% of summer and winter elk locations, respectively. Our population-level models and associated predictive maps were successful in predicting winter and summer habitat use by elk in a nonforested environment. In the absence of forest cover, elk seemed to rely on a combination of shrubs, topography, and low human disturbance to meet their thermal and hiding cover requirements.     

The effects of sheep grazing on invertebrate numbers and biomass in unfertilized natural pastures of the New England Tablelands (NSW)

Invertebrate components of natural pastures which were grazed continuously by sheep at three stocking intensities, were sampled each season for more than two years. Grazing resulted in a significant reduction in abundance of litter and topsoil micro-arthropods. Two samplings for nematodes and enchytraeids showed similar reductions with grazing. Grazing effects on the vertical distribution of mesofauna were not consistent but all sites had greatest numbers in the 0 – 5 cm topmost soil layer. Fresh biomass of large soil and litter dwelling invertebrates also declined with grazing, with proportionally greater reductions occurring for litter animals. Changes in invertebrate populations were associated with changes in living space, microclimate and food supply. Populations of invertebrates on natural pastures were about one-third those found on previously studied sown, fertilized pastures at Armidale.     

Bile salts of fishes collected on the Zaire River Expedition (1974-5): their chemical nature and its possible significance

Bile salts from 21 fish species caught during the Zaïre River Expedition (1974–5) have received partial or complete chemical analysis. Conclusions from the results are as follow. (1) Polypterus bile salts are biochemically advanced, but with easily detectable features regarded as relicts from ancestral stock. The bile acids include haemulcholic acid, previously found only in a marine teleost and an unidentified acid also found in a mormyrid. (2) This mormyrid has advanced bile salts, consisting almost entirely of taurine conjugates of haemulcholic acid (present in Polypterus) , and two other C₂₄ acids. (3) Three Alestes and three Distichodus species have no more than traces of primitive bile salts; their bile acids suggest a degree of activity of intestinal microorganisms during the enterohepatic circulation not previously noticed in fishes. (4) The predatory Hydrocynus has bile acids of an omnivorous rather than a carnivorous type. (5) The Barbus species have primitive bile salts closely similar to those of Cyprinidae previously examined but containing also (in two species) a newly-discovered bile alcohol sulphate: in contrast, a Varicorhinus does not have this new substance and has a chief bile salt found so far only as a minor constituent in the Cyprinidae. (6) Two Labeo species are different from all other cyprinids examined: diey both have a new major bile alcohol sulphate. (7) Four Siluriformes show evidence of enterohepatic changes that might be characteristic of some tropical freshwater fish; three have taurine-conjugated haemulcholic acid. (8) Synodontis species are remarkable in having a high proportion of unconjugated bile acid ions and this finding was confirmed with fresh material.     

Blood Protozoa of Wild Turkeys in Florida*

From 1969 through 1972, 605 wild turkeys (Meleagris gallopavo Linnaeus) from 10 localities in Florida were examined for blood protozoans. The prevalence in turkeys more than a month old was 84% for Haemoproteus meleagridis Levine, 1961 and 72% for Leucocytozoon smithi Laveran and Lucet, 1905. Sixty-three percent of the birds were infected by both parasites. Infections were most prevalent in juveniles 8–12 months of age. No infection of H. meleagridis or L. smithi was found in 111 poults younger than 35 days. Prevalences were similar in both sexes. Haemoproteus meleagridis was more prevalent (87%) in the southern part of the state; L. smithi was more prevalent (75%) in the north. The prevalence of H. meleagridis did not change during the 4 year period, but L. smithi decreased markedly in 1971, a year of low rainfall. None of the 605 blood films was positive for Plasmodium, but 24 (75%) of 32 blood samples were found by subinoculation technics to be positive for a species of Plasmodium morphologically similar to P. durae Herman, 1941. No trypanosomes were seen on the 605 blood films or in bone marrow cultures (saline-neopeptone-blood) made from 11 turkeys.     

Concluding Remarks: American Natural History and Biology in the Nineteenth Century

SYNOPSIS. This symposium has illustrated the important rolethat amateur naturalists played in preparing the groundworkfor professional science in the west. Like their eastern counterparts,these naturalists popularized science to the public, createdimpressive collections of natural history artifacts, formeda network of fellow enthusiasts, and initiated the establishmentof organizations and publications to further their interests.This heritage was critical to the development of the professionalbiology community in America and must be emphasized in the historyof American biology in order to understand the unique developmentof the biology community in the United States.     

Believers and Beaters: A Case Study of Supernatural Beliefs and Child Rearing in the Bahama Islands

The research described in this article tests the hypothesis that caretakers who fear the supernatural will inflict more pain on the children in their charge than will those caretakers who do not fear the supernatural. The hypothesis is drawn from a larger body of theory which states that child training practices influence adult personality, including beliefs in the supernatural—these beliefs in turn influence the training of children. In order to test the hypothesis it was necessary to find a group of people whose adults differ from each other in theirbeliefs in the supernatural and whose children receive differential training. The village of Congo Town, located on Andros Island in the Bahamas, provides such a group of people. In the course of ethnographic fieldwork carried out in 1968 in this village, twenty caretakers were interviewed about the training given to their forty-eight children and grandchildren, as well as about their beliefs in the supernatural. Differences both in beliefs in the supernatural and in child training practices exist. Three specific hypotheses are derived from the major hypothesis described above. Each of these hypotheses is found to be supported by data gathered in Congo Town. Since each of the derived hypotheses receives support, it is concluded that the major hypothesis is confirmed.     

Developmentally-Regulated Virulence Factors of Trypanosoma cruzi and Their Relationship to Evasion of Host Defences1

ABSTRACT. Developmental preadaptation of virulent stages of Trypanosoma cruzi correlates with their ability to survive and establish infection in mammalian hosts. Infective trypomastigote stages must first preadapt to survival in the extracellular milieu and then to the rigors of establishing an intracellular infection. Selected phenotypic variations in evading host defences have been correlated with expression of stage-specific proteins or functions. Resistance of trypomastigotes to complement-mediated killing correlates with the presence of a stage-specific molecule that exhibits an analogous function to mammalian decay-accelerating factor, and with the presence of a neuraminidase/trans-sialidase that transfers sialic acid moieties to the parasite surface, thereby enabling it to avoid complement activation. Trypomastigotes enter cells by a mechanism that involves sorting of cell surface receptors and avoids eliciting a respiratory burst. Once within a membrane-bound vacuole, which undergoes acidification, the neuraminidase/trans-sialidase and an acid-active, transmembrane pore-forming protein are released by the parasite and are capable of acting together to accelerate rupture of the vacuolar membrane and the parasite's escape into the cytoplasm of the host cell. Escape from the parasitophorous vacuole allows virulent stages of T. cruzi to avoid compartmental, non-oxidative killing mechanisms such as degradation by lysosomal hydrolases.     

THE NASAL APPARATUS IN DIPNOI, WITH SPECIAL REFERENCE TO PROTOPTERUS

An investigation is made of the homology of the nasal apparatus of the Dipnoi, in order to determine whether the posterior naris is homologous with the choana of tetrapods or with the posterior external naris of fishes. The ontogeny of the nasal capsule of Protopterus is described in detail. The nervous and venous systems of tho snout region of Protopterus are also duscrbed. It is found that whereas the pattern of the nervous and vascular systems is very similar in all Dipnoi, the structuro of the nasal capsule in the Lepidosiren-Protopterus stock differs greatly from that of the Neoceratodus stock. the homology of the various components of the depnoan nasal coasule is revised and it is shown that there are no evidences of a direct relationship of the Dipnoi with the tetrapods. It is further concluded that the posterior naris of Dipnoi is homologous with the posterior external naris of fishes.