Multi-scale impacts of urbanization on species distribution within the genus Tetramorium

Landscape Ecology - Urbanization is a global change which deeply impacts landscapes. Long studied through transects along urbanization gradients, ecological response to urbanization can now be...     

Using landscape graphs to delineate ecologically functional areas

Context

Landscape graphs are widely used to model connectivity and to support decision-making in conservation planning. Compartmentalization methods applied to such graphs aim to define clusters of highly interconnected patches. Recent studies show that compartmentalization based on modularity is suitable, but it applies to non-weighted graphs whereas most landscape graphs involve weighted nodes and links.

Objectives

We propose to adapt modularity computation to weighted landscape graphs and to validate the relevance of the resulting compartments using demographic or genetic data about the patches.

Methods

A weighted adjacency matrix was designed to express potential fluxes, associating patch capacities and inter-patch distances. Eight weighting scenarios were compared. The statistical evaluation of each compartmentalization was based on Wilks’ Lambda. These methods were performed on a grassland network where patches are documented by annual densities of water voles in the Jura massif (France).

Results

The scenarios in which patch capacity is assigned a small weight led to the more relevant results, giving high modularity values and low Wilks’ Lambda values. When considering a fixed number of compartments, we found a significant negative correlation between these two criteria. Comparison showed that compartments are ecologically more valid than graph components.

Conclusions

The method proposed is suitable for designing ecologically functional areas from weighted landscape graphs. Maximum modularity values can serve as a guide for setting the parameters of the adjacency matrix.

     

The Blonde d’Aquitaine T3811>G3811 mutation in the myostatin gene: association with growth,carcass, and muscle phenotypes in veal calves

The mutation T3811 → G3811 (TG3811) discovered in the myostatin gene of the Blonde d’Aquitaine breed is suspected of contributing to the outstanding muscularity of this breed. An experiment was designed to estimate the effect of this mutation in an F2 and back-cross Blonde d’Aquitaine × Holstein population. By genotyping all known mutations in the myostatin gene, it was ensured that the TG3811 mutation was indeed the only known mutation segregating in this population. Fifty-six calves (43 F2, 13 back-cross) were intensively fattened and slaughtered at 24.0 ± 1.4 wk of age. The effects of the mutation were estimated by comparing the calves with the [T/T] (n = 18), [T/G] (n = 30), and [G/G] (n = 8) genotypes. Highly significant substitution effects (P < 0.001), above + 1.2 phenotypic SD, were shown on carcass yield and muscularity scores. Birth weight (P < 0.001) was positively affected by the mutation (+0.8 SD) but not growth rate (P = 0.97), while carcass length (P = 0.03), and fatness (P ≤ 0.03) were negatively affected (–0.5 to –0.7 SD). The characteristics of the Triceps brachii muscle were affected by the mutation (P < 0.001), with lower ICDH activity (oxidative) and a higher proportion of myosin type 2X muscle fibers (fast twitch). The effects of the TG3811 mutation were similar to those of other known myostatin mutations, although the Blonde d’Aquitaine animals, which are predominantly [G/G] homozygous, do not exhibit extreme double muscling.     

Health status and risk factors associated with failure of passive transfer of immunity in newborn beef calves in Québec

Risk factors associated with failure of passive transfer of immunity (FPT) were evaluated among newborn beef calves in Québec. Physical examination was performed on calves born of a normal calving and blood samples were collected for determination of health status and measurement of serum concentration of immunoglobulin (Ig) G1. Of 225 calves, from 45 herds, 19% showed FPT (serum IgG1 concentration < 10.0 g/L). Calves born in a stanchion-stall were more likely to show FPT (OR: 10.2). Calves bottle-fed colostrum were less at risk for FPT (OR: 0.06). Calf gender, month of birth, dam parity, and dam body condition score were not associated with FPT. No association was detected between FPT and health status. Special care should be given to calves born from cows in a stanchion-stall to ensure adequate colostrum intake. Failure of passive transfer of immunity should be considered with other risk factors when investigating morbidity.     

Thoracoscopic treatment of bullous emphysema in 3 dogs

OBJECTIVE: To report thorascopic partial lobectomy for treatment of bullous emphysema in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: Three dogs with spontaneous pneumothorax. METHODS: Thoracoscopy without pulmonary exclusion was used to identify bulla. The thorascope was introduced into the thorax lateral to the xyphoid process, and instrument portals were made at different levels along the thoracic wall between the third and tenth intercostal spaces. The thorascope was passed through the mediastinum to view the opposite pleural cavity. After identification of bullae, the affected lung was excised using an endoscopic stapler, and the incision line was checked for air leakage. Thoracic drains were used for air aspiration for 2 days after surgery. RESULTS: Bullae were confirmed histologically as emphysematous lesions. Lung inflation did not interfere with identification of bullae or with surgery. All dogs had full recovery without recurrence for 18 to 29 months after surgery. CONCLUSIONS: Identification and ablation of bulla can be performed thoracoscopically without pulmonary exclusion in dogs. CLINICAL RELEVANCE: Thoracoscopy offers several advantages compared with thoracotomy for treatment and diagnosis of idiopathic pneumothorax, including ease of identification of bullae and reduced postoperative pain and morbidity.     

Some safety aspects of salmonella vaccines for poultry: distribution and persistence of three Salmonella typhimurium live vaccines

The purpose of this study was to analyze the safety characteristics of three commercially available live Salmonella vaccine strains (vacT, Zoosaloral, and X3985) in relation to their persistence in individual animals but also within a flock and in the environment. In a first experiment, the digestive and systemic distributions in chickens were followed for 10 days in individually reared chickens that were orally inoculated at 1 day of age. Strain X3985 quickly disappeared from the digestive tract but remained in the liver until the end of this experiment, whereas strains vacT and Zoosaloral colonized the liver as well as the gut for 10 days. In the second trial, behavior of the vaccine strains was studied in groups of 20 chickens during 10 wk after a single oral administration to individual birds. Strain vacT remained in the environment of inoculated animals for 4-5 wk. Six weeks after the inoculation, vacT was not recovered from internal organs such as liver and spleen, and vacT disappeared from the digestive tract between the sixth and the 10th weeks. Comparatively, both Zoosaloral and X3985 vaccine strains persisted longer in the environment (8 wk at least). Of the vaccine strains, X3985 showed the greatest colonization of both systemic and digestive organs.     

Changes in fatty acid and sterol composition during oogenesis in the pearl oyster Pinctada margaritifera

The fatty acid and sterol composition of the oyster Pinctada margaritifera during oogenesis and in eggs was analysed. No major differences were observed during oogenesis, but the egg composition was significantly different from that of gonads. The amount of saturated fatty acids was the highest in eggs and the C16:0 predominant (P<5%); by contrast, the amount of 22:6(n‐3) was significantly lower (P<5%) than in gonads. No major differences were observed for the polar lipid (PL) composition during oogenesis. The main free sterols in gonads and eggs were cholesterol and brassicasterol. Among free sterols, the proportion of cholesterol diminished continuously from the beginning to the end of gonad maturation, and this decrease persisted in eggs after spawning. Cholesterol represented 40% to 55% of the sterol ester encountered in gonad and eggs. This study allowed us to investigate the fatty acid and sterol composition during oogenesis of the pearl oyster P. margaritifera, leading to a clearer understanding of the nutritional requirements of pearl oyster during the reproduction process.