Diversity, geographic distribution and habitat specific variations of microbiota in natural populations of the chicken mite, Dermanyssus gallinae

On-line reproduction of the statistical analyses and figures of the paper by Valiente Moro et al. (2010)*
This web page allows to redo the computations and graphical displays of the three multivariate analyses presented in the paper (thanks to the Rweb system).
The full R code is available here: allCode.R.

* Valiente Moro C., Thioulouse J., Chauve C., Zenner L. (2010). Diversity, geographic distribution and habitat specific variations of microbiota in natural populations of the chicken mite, Dermanyssus gallinae. Journal of Medical Entomology 48, 788-796.

Abstract:

Dermanyssus gallinae is considered to be the most economically significant ectoparasite affecting egg-laying poultry in Europe. This mite can also act as a vector for a number of pathogens. To date, little information is available concerning the array of bacteria associated with D. gallinae mites while it could provide insight into the biology and population dynamics of arthropods. In order to understand intra- and inter population diversity of its associated microbiota, we analysed the whole internal bacterial community of natural populations of D. gallinae originating from two types of poultry farm habitats (standard and free-range) in two regions of France (Brittany and Rhône-Alpes). Total DNA was extracted from individual or pooled mites, and PCR temporal temperature gradient gel electrophoresis of 16S rRNA was then undertaken to separate bacterial DNA fragments associated with the host arthropod. A large diversity of bacteria was detected including mainly firmicutes and gammaproteobacteria. Between Group analyses of TTGE banding patterns revealed that bacterial populations clustered into categories according to geographical origin and habitat specific of farms. Some degree of stability of bacterial populations was observed within a specific time year scale. These results suggest that environmental factors that could be recent (e.g. poultry farming practices) or long-standing (e.g. geographic isolation) may affect bacterial communities assembly in D. gallinae . Further knowledge of microbiota associated D. gallinae and its variation would indeed offer new perspectives of biological control in preventing the establishment, proliferation and transmission of pathogenic bacteria.

Key words:

D. gallinae , microbiota, diversity, biological control

1. BGA on geographical effect

Importing data is done by reading the DataReg.txt file that contains the TTGE presence-absence data for the 87 pools. The corresponding data is stored in the br1 dataframe. Columns of zeroes are removed and the resulting table is stored in dataframe br1sz. Farm codes are read from file FarmReg.txt, and pool numbers for each farm are read from file FarmRegNum.txt. The farms factor is build from these two objects. It is used to compute the between-farms BGA and plot Figure 3 of the paper.

The regions factor is read from file Regions.txt. It is used to build the repreg factor, which is needed to compute the between-regions permutation test.

#
# BGA on geographical effect
#
br1 <- read.table("DataReg.txt", h=T)
br1sz <- br1[,colSums(br1)!=0]
fnum <- scan("FarmRegNum.txt")
fnames <- scan("FarmReg.txt", what="character")
farms <- as.factor(rep(fnames, fnum))
regions <- as.factor(scan("Regions.txt", what="character"))
repreg <- rep(regions, fnum)

The PCA and the BGA are then computed using the dudi.pca and bca functions of the ade4 package. The corresponding figure (Figure 3 of the paper) is drawn using the s.class funtion and is presented below.

#
# PCA and BGA computation and plot
#
acp1 <- dudi.pca(br1sz, scale=F, scan=F)
betfarms <- bca(acp1, farms, scan=F)
s.class(betfarms$ls, farms, cell=0, cpoint=0)

The permutation test is done with the randtest function:

#
# Between-regions permutation test
#
betregs <- bca(acp1, repreg, scan=F, nf=1)
print(randtest(betregs))

You can click on the "Do it again !" button to execute the R code contained in the text field under the figure. All the computations are redone automatically and the factor map is plotted.

BGA on TTGE profiles of D. gallinae associated microbiota from Brittany and Rhone-Alp farms. BS = Brittany Standard farms. RS = Rhone-Alp Standard farms. The value d in the upper-right corner is the size of the background grid and gives the scale of the graphic. The five samples from each farm are grouped and linked to the farm label to form a five-pointed irregular star. Brittany farms are located on the left of the graphic, and they are opposed to Rhone-Alp farms, which are on the right. The only exception is farm BS16, which is located among Rhone-Alp farms.


2. BGA on habitat-specific effect

Importing data is done by reading the DataHS.txt file that contains the TTGE presence-absence data for the 65 pools (13 farms x 5 pools for each farm). The corresponding data is stored in the pasr1 dataframe. Columns of zeroes are removed and the resulting table is stored in dataframe pasr1sz. Farm codes are read from file FarmHS.txt. The number of pools is equal to 5 for all the farms. The farmsPASR factor is build from these two objects. It is used to compute the between-farms BGA and plot Figure 4 of the paper.

#
# BGA on habitat-specific effect
#
pasr1 <- read.table("DataHS.txt",h=T)
pasr1sz <- pasr1[,colSums(pasr1)!=0]
fnamesPASR <- scan("FarmHS.txt", what="character")
farmsPASR <- as.factor(rep(fnamesPASR, 5))

The PCA and the BGA are then computed using the dudi.pca and bca functions of the ade4 package. The corresponding figure (Figure 4 of the paper) is drawn using the s.class funtion and is presented below.

#
# PCA and BGA computation and plot
#
acpPASR <- dudi.pca(pasr1sz, scan=F)
betPASR <- bca(acpPASR, farmsPASR, scan=F)
s.class(dfxy = betPASR$ls, fac = farmsPASR, cellipse = 0, cpoint = 0)

The permutation test is done with the randtest function, after computing a new BGA with the fPASR factor, which is read from file CodePAS.txt.

#
# Between-habitat permutation test
#
fPASR <- as.factor(scan("CodePAS.txt", what="character"))
betPASRv <- bca(acpPASR, fPASR, scan=F, nf=1)
print(randtest(betPASRv))

You can click on the "Do it again !" button to execute the R code contained in the text field under the figure. All the computations are redone automatically and the factor map is plotted.

BGA on TTGE profiles of D. gallinae associated microbiota from standard and free-range Rhone-Alp farms. RFR = Rhone-Alp free-range farms. RS = Rhone-Alp Standard farms. The value d in the upper-right corner is the size of the background grid and gives the scale of the graphic. The five samples from each farm are grouped and linked to the farm label to form a five-pointed irregular star. Standard farms are located on the left of the graphic, and they are opposed to Free-range farms, which are on the right. The within-farm diversity for free-range farms is higher than for standard farms.


3. Inter-region and inter-habitat comparisons

Importing data is done by reading the DataRegHS.txt file that contains the TTGE presence-absence data for the 127 pools (26 farms x 5 pools for each farm less 3 pools missing in two farms). The corresponding data is stored in the glob dataframe. Columns of zeroes are removed and the resulting table is stored in dataframe globsz. Farm codes are read from file FarmRegHS.txt, and pool numbers for each farm are read from file FarmRegHSNum.txt. The farmsG factor is build from these two objects. It is used to compute the between-farms BGA and plot Figure 5 of the paper. The typeG factor is read from file TypeRegHS.txt. It is used to build the ftypeG factor, which is used itself to compute the permutation test.

#
# Inter-region and inter-habitat comparisons
#
glob <- read.table("DataRegHS.txt", h=T)
globsz <- glob[,colSums(glob)!=0]
fnamesG <- scan("FarmRegHS.txt", what="character")
fnumG <- scan("FarmRegHSNum.txt", what="character")
farmsG <- as.factor(rep(fnamesG, fnumG))
typeG <- scan("TypeRegHS.txt", what="character")
typeG <- as.factor(typeG)
ftypeG <- rep(typeG, fnumG)

The PCA and the BGA are then computed using the dudi.pca and bca functions of the ade4 package. The corresponding figure (Figure 5 of the paper) is drawn using the s.class funtion and is presented below.

#
# PCA and BGA computation and plot
#
acpG <- dudi.pca(globsz, scale=F, scan=F)
betfarmsG <- bca(acpG, farmsG, scan=F)
bettypeG <- bca(acpG, ftypeG, scan=F)
s.class(dfxy = bettypeG$ls, fac = farmsG, cellipse = 0, cpoint = 0)
s.class(dfxy = bettypeG$ls, fac = ftypeG, add.plot=T, cstar=0, cpoint=0, clabel=0, axesell=F)

The permutation test is done with the randtest function.

#
# Permutation test
#
print(randtest(bettypeG))

You can click on the "Do it again !" button to execute the R code contained in the text field under the figure. All the computations are redone automatically and the factor map is plotted.

BGA on TTGE profiles of D. gallinae associated microbiota for all the farms. RFR = Rhone-Alp free-range farms. RS = Rhone-Alp Standard farms. BS = Brittany Standard farms. The value d in the upper-right corner is the size of the background grid and gives the scale of the graphic. The five samples from each farm are grouped and linked to the farm label to form a five-pointed irregular star. The three ellipses are the inertia ellipses corresponding to the three groups of farms. Rhone-Alp farms are located on the left of the graphic, and they are opposed to Brittany farms, which are on the right. Free-range Rhone-Alp farms are in the lower-left part of the graphic, and they are opposed to standard farms, which are in the upper part. These three groups of farms are almost completely separated, with the exception of farm BS16, which is located among Rhone-Alp standard farms. The within farm diversity is comparable for the three groups



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