12 research outputs found
VALIDATION OF HEATING CONDITIONS IN PRODUCTION OF DIRECT ACIDIFIED BEEF SUMMER SAUSAGE FOR ELIMINATION OF ESCHERICHIA COLI O157:H7
Genotypic analysis of Escherichia coli recovered from product and equipment at a beef-packing plant
Survival of verocytotoxin-producing Escherichia coli 0157 under simulated farm conditions
Detection of genetic diversity by pulsed-field gel electrophoresis among Escherichia coli O157 isolated from bovine faecal samples by immunomagnetic separation technique
Effects of divercin V41 combined to NaCl content, phenol (liquid smoke) concentration and pH on Listeria monocytogenes ScottA growth in BHI broth by an experimental design approach
Intermittent and persistent shedding of Escherichia coli O157 in cohorts of naturally infected calves
INHIBITION OF LISTERIA INNOCUA AND L. MONOCYTOGENES IN A LABORATORY MEDIUM AND COLD-SMOKED SALMON CONTAINING LIQUID SMOKE
Characterizing the phylogenetic structure of communities by an additive partitioning of phylogenetic diversity
1 Analysing the phylogenetic structure of natural communities may illuminate the processes governing the assembly and coexistence of species in ecological communities. 2 Unifying previous works, we present a statistical framework to quantify the phylogenetic structure of communities in terms of average divergence time between pairs of individuals or species, sampled from different sites. This framework allows an additive partitioning of the phylogenetic signal into alpha (within-site) and beta (among-site) components, and is closely linked to Simpson diversity. It unifies the treatment of intraspecific (genetic) and interspecific diversity, leading to the definition of differentiation coefficients among community samples (e.g. I-ST, P-ST) analogous to classical population genetics coefficients expressing differentiation among populations (e.g. F-ST, N-ST). 3 Two coefficients which express community differentiation among sites from species identity (I-ST) or species phylogeny (P-ST) require abundance data (number of individuals per species per site), and estimators that are unbiased with respect to sample size are given. Another coefficient (Pi(ST)) expresses the gain of the mean phylogenetic distance between species found in different sites compared with species found within sites, and requires only incidence data (presence/absence of each species in each site). 4 We present tests based on phylogenetic tree randomizations to detect community phylogenetic clustering (P-ST > I-ST or Pi(ST) > 0) or phylogenetic overdispersion (P-ST < I-ST or Pi(ST) < 0). In addition, we propose a novel approach to detect phylogenetic clustering or overdispersion in different clades or at different evolutionary time depths using partial randomizations. 5 I-ST, P-ST or Pi(ST) can also be used as distances between community samples and regressed on ecological or geographical distances, allowing us to investigate the factors responsible for the phylogenetic signal and the critical scales at which it appears. 6 We illustrate the approach on forest tree communities in Equatorial Guinea, where a phylogenetic clustering signal was probably due to phylogenetically conserved adaptations to the elevation gradient and was mostly contributed to by ancient clade subdivisions. 7 The approach presented should find applications for comparing quantitatively phylogenetic patterns of different communities, of similar communities in different regions or continents, or of populations (within species) vs. communities (among species).FLWINinfo:eu-repo/semantics/publishe