A new method to estimate species and biodiversity intactness using empirically derived reference conditions

Critical to the conservation of biodiversity is knowledge of status and trends of species. To that end, monitoring programmes have reported on the state of biodiversity using reference conditions as comparison. Little consensus exists on how reference conditions are defined and how such information is used to index intactness. Most use protected areas or an arbitrary year as reference. This is problematic since protected areas are often spatially biased, while arbitrarily defined reference years are often not sufficiently distant in time. We propose an alternative that relies on empirical estimates of reference conditions. Statistical ranges of reference are estimated and compared with observed occurrence and abundance to index status of individual species. When averaged among species, overall intactness is estimated. We demonstrate the approach using 202-winter mammal tracking sites from the boreal forest of Alberta, Canada. Intactness was estimated at 89 out of 100 with the southern boreal having lowest intactness and greatest human footprint. We suggest empirical predictions of reference conditions be used as baselines for comparing changes in the state of species and biodiversity. Reporting can occur at any spatial (e.g., ecosystem) or hierarchical (e.g., species, guilds, taxonomic group, or overall biodiversity) scale and is easily interpreted (scaled from 0-degraded to 100-intact). When used in a long-term monitoring framework, statistical trends in biodiversity intactness can be estimated, individual status of species assessed, and relevant policy evaluated.     

Administration of probiotics influences F4 (K88)-positive enterotoxigenic Escherichia coli attachment and intestinal cytokine expression in weaned pigs

ABSTRACT: This study evaluated the effect of the probiotics Pediococcus acidilactici and Saccharomyces cerevisiae boulardii on the intestinal colonization of O149 enterotoxigenic Escherichia coli harbouring the F4 (K88) fimbriae (ETEC F4) and on the expression of ileal cytokines in weaned pigs. At birth, different litters of pigs were randomly assigned to one of the following treatments: 1) control without antibiotics or probiotics (CTRL); 2) reference group in which chlortetracycline and tiamulin were added to weanling feed (ATB); 3) P. acidilactici; 4) S. cerevisiae boulardii; or 5) P. acidilactici + S. cerevisiae boulardii. Probiotics were administered daily (1 × 109 CFU per pig) during the lactation period and after weaning (day 21). At 28 days of age, all pigs were orally challenged with an ETEC F4 strain, and a necropsy was performed 24 h later. Intestinal segments were collected to evaluate bacterial colonization in the small intestine and ileal cytokine expressions. Attachment of ETEC F4 to the intestinal mucosa was significantly reduced in pigs treated with P. acidilactici or S. cerevisiae boulardii in comparison with the ATB group (P = 0.01 and P = 0.03, respectively). In addition, proinflammatory cytokines, such as IL-6, were upregulated in ETEC F4 challenged pigs treated with P. acidilactici alone or in combination with S. cerevisiae boulardii compared with the CTRL group. In conclusion, the administration of P. acidilactici or S. cerevisiae boulardii was effective in reducing ETEC F4 attachment to the ileal mucosa, whereas the presence of P. acidilactici was required to modulate the expression of intestinal inflammatory cytokines in pigs challenged with ETEC F4.     

Lateral canthal fibroma in a dog

A 9-year-old castrated male pitbull dog was presented for evaluation of a subconjunctival swelling of 10 days duration. On ophthalmic examination, a subcutaneous mass was identified at the right lateral canthus. An excisional biopsy was performed, and histopathological analysis confirmed a diagnosis of a subcutaneous fibroma. Eleven months after surgical excision, the dog had no evidence of recurrence. Fibroma should be included in the differential diagnosis of rapidly enlarging eyelid masses.     

Structural differences and functional similarities between two sugar maple (Acer saccharum) stands

The spatially inexplicit or functional multilayer models used to predict canopy transpiration or photosynthesis are based on the assumption that closed stands show less functional variability than structural variability, because foliage tends to arrange itself in space to optimize the capture of light. To validate this assumption, we compared the structural and functional properties, and the measured and modeled transpiration fluxes of two sugar maple (Acer saccharum Marsh.) stands of comparable leaf mass but differing in height and diameter distributions. One stand was characterized by a well-developed single-layer canopy, whereas the other stand had a multilayered canopy and a stem diameter distribution of the classical inverse-J shape. Stand differences in height and diameter distribution, and canopy gap fraction, were highly significant. There were minor but significant differences in leaf mass and leaf mass per unit leaf area (LMA) distributions. We found no differences in tree-level relationships between basal area and either transpiration flux or sapwood area. We compared measurements of stand transpiration with transpiration estimates obtained from a multilayer gas exchange model, in which only the nonspatial inputs, leaf area index and LMA frequency distribution described stand structure. For both stands, modeled values of daily transpiration closely followed measured values (r(2) = 0.94). These results support use of the nonspatially explicit approach to estimating canopy gas exchange, especially if the intent is to scale-up to larger portions of the landscape.     

Genetic diversity and relatedness of boreal caribou populations in western Canada

We studied genetic diversity within and gene flow among six ‘threatened’ populations of boreal caribou (Rangifer tarandus caribou) inhabiting Alberta and British Columbia, Canada. Mean expected heterozygosity (H_E) across 11 loci spanned a narrow range between 0.74 and 0.79. Estimates of H_E were in the mid to high range of those typically observed in natural populations of large mammals, including caribou, and were not suggestive of any immediate threat to survival. We concluded that recent anthropogenic fragmentation of caribou range in western Canada has yet to affect genetic diversity of populations. Analysis of population structure identified a region of relatively low gene flow corresponding with the valley of the Peace River. The highest value of F_ST observed between populations on the same side of the river was 0.025, whereas the lowest value that spanned the river was 0.044. Confirming this result, an assignment test demonstrated that 96.5% of animals could be assigned to the correct side of the Peace River, though only 66.0% of animals could, on average, be assigned to populations of actual origin. Taken as a whole, our results support the existence of two discrete metapopulations bisected by the Peace River, within each of which there exist multiple populations, or at least multiple regions, which experience considerably higher levels of interchange. For caribou inhabiting the boreal plains, large rivers such as the Peace and Mackenzie may serve as biologically meaningful boundaries for managing metapopulations.     

Effects of soil freezing and drought stress on abscisic acid content of sugar maple sap and leaves

In 1991 and 1992, mature maple trees (Acer saccharum Marsh.) were freeze-stressed or drought-stressed by preventing precipitation (snow or rain) from reaching the forest floor under selected trees. Lack of snow cover caused a decrease in soil temperature to well below 0 degrees C from December to April and a lowering of the soil water content to 10%. The abscisic acid (ABA) concentration in the spring sap of deep-soil frost-stressed trees was significantly higher than in control or drought-stressed trees. The increase in ABA concentration in the xylem sap in the spring of 1991 and 1992 preceded symptoms of canopy decline and a decrease in leaf area that were observed during the summers of 1991 and 1992. These results suggest a role for ABA in root-to-shoot communication in response to environmental stress. The largest differences in ABA concentration induced by the treatments was found in sap collected at the end of sap flow. The increase in ABA concentration in spring sap at the end of the sap flow could be used as an early indicator of stress suffered by trees during the winter. Not only did the increase in ABA concentration occur before any visible symptoms of tree decline appeared, but the trees that showed the most evident decline had the highest ABA concentrations in the spring sap. Leaf ABA concentration was not a good indicator of induced stress.     

Limited impacts of extensive human land use on dominance,specialization, and biotic homogenization in boreal plant communities

Background

Niche theory predicts that human disturbance should influence the assembly of communities, favouring functionally homogeneous communities dominated by few but widespread generalists. The decline and loss of specialists leaves communities with species that are functionally more similar. Evenness of species occupancy declines, such that species become either widespread of rare. These patterns have often been observed, but it is unclear if they are a general result of human disturbance or specific to communities that are rich in species, in complex, spatially heterogeneous environments where the problem has often been investigated. We therefore tested whether human disturbance impacts dominance/evenness of species occupancy in communities, specialism/generalism of species, and functional biotic homogenization in the spatially relatively homogeneous, species poor boreal forest region of Alberta, Canada. We investigated 371 boreal vascular plant communities varying 0 – 100% in proportion of human land use.

Results

Rank species occupancy curves revealed high species dominance regardless of disturbance: within any disturbance class a few species occupied nearly every site and most species were found in a low proportion of sites. However, species were more widespread and displayed more even occupancy in intermediately disturbed communities than among communities of either low or high disturbance. We defined specialists and generalists based on turnover in co-occupants and thereby assessed impacts of human disturbance on specialization of species and community homogenization. Generalists were not disproportionately found at higher disturbance sites, and did not occupy more sites. Communities with greater human disturbance were not more functionally homogeneous; they did not harbor communities with more generalists.

Conclusions

We unexpectedly did not observe strong linkages between species specialism/generalism and disturbance, nor between community homogenization and disturbance. These results contrast previous findings in more species rich, complex or spatially heterogeneous systems and ecological models. We suggest that broad occupancy-based intercommunity patterns are insensitive to human land use extent in boreal vascular plants, perhaps because of ubiquity of generalists, low species richness, and history of natural disturbance. The poor sensitivity of these metrics to disturbance presents challenges for monitoring and managing impacts to biodiversity in this region.     

Impact of food and predation on the snowshoe hare cycle

Snowshoe hare populations in the boreal forests of North America go through 10-year cycles. Supplemental food and mammalian predator abundance were manipulated in a factorial design on 1-square-kilometer areas for 8 years in the Yukon. Two blocks of forest were fertilized to test for nutrient effects. Predator exclosure doubled and food addition tripled hare density during the cyclic peak and decline. Predator exclosure combined with food addition increased density 11-fold. Added nutrients increased plant growth but not hare density. Food and predation together had a more than additive effect, which suggests that a three-trophic-level interaction generates hare cycles.     

Trimming as a means of removing patulin from fungus-rotted apples.

Penicillium expansum 1071, 1172, NRLL 973, and Penicillium patulum ATCC 24550 were inoculated into Red Delicious, Golden Delicious, and McIntosh apples. The decayed tissue was trimmed from the sound tissue, each fraction was weighed, and the patulin concentration in the juice was assayed by thin layer chromatography. The quantity of patulin in the whole apples and in decayed tissues was calculated and these values were used to determine the percentage of total patulin removed by trimming. The patulin content ranged from 140 to 4880 mug/apple. Trimming removed 93-99% of the total patulin, regardless of incubation temperature, fungus strain, or apple variety. Trimming of defective tissue from fungus-rotted apples could substantially reduce the patulin concentration.