[adegenet-forum] Structure-like membership plot

Huang,Cheng-Hua arhua at ufl.edu
Mon Jul 4 17:09:04 CEST 2011

Dear Thibaut,

Thank you for your help. I used the way you advised me to convert the Strucutre file of my haploid data set into a genind object as follow:

dat <- read.table("structure.str", sep="\t",head=TRUE)
x <- df2genind(dat[,-(1:2)], ploidy=1, pop=dat[,2], ind.names=dat[,1])
and then

However, the membership plot derived from this Structure file (showing admixture individuals) was different those obtained from using import2genind to convert Genepop and Fstat files of the same data set where data were coded as a pseudo-diploid (no admixture individuals). Did I convert my structure data set wrong? Or, I should trust results from Genepop and Fstat data sets? Thank you.

From: Jombart, Thibaut [mailto:t.jombart at imperial.ac.uk]
Sent: Monday, July 04, 2011 9:30 AM
To: Huang,Cheng-Hua; adegenet-forum at r-forge.wu-wien.ac.at
Cc: arhuahuang at gmail.com
Subject: RE: [adegenet-forum] Structure-like membership plot

Dear Arhua,

read.structure is only meant for diploid data - will add a warning on this point in the doc for 1.3-1.

So your analysis based on read.structure here is wrong. The other analyses are surely OK. Otherwise use read.table/read.csv to read your structure data into R as a data.frame, and then df2genind with the proper arguments to convert the data into a genind object.



Dr Thibaut JOMBART
MRC Centre for Outbreak Analysis and Modelling
Department of Infectious Disease Epidemiology
Imperial College - Faculty of Medicine
St Mary's Campus
Norfolk Place
London W2 1PG
United Kingdom
Tel. : 0044 (0)20 7594 3658
t.jombart at imperial.ac.uk
From: adegenet-forum-bounces at r-forge.wu-wien.ac.at [adegenet-forum-bounces at r-forge.wu-wien.ac.at] on behalf of Cheng-Hua Huang [arhua at ufl.edu]
Sent: 01 July 2011 17:10
To: adegenet-forum at r-forge.wu-wien.ac.at
Cc: arhuahuang at gmail.com
Subject: [adegenet-forum] Structure-like membership plot
Dear adegent users and Thibaut,
I would like to ask questions about using DAPC. I have used import2genind and df2genind for importing Structure, Genepop, and Fstat files of the same data set to find clusters and to plot Struture-like membership information. Since I was working on a haploid, asexual fungus collected from three regions, I coded data sets as a pseudo-diploid for Genepop and Fstat files but used the original haploid data set for the Structure format. Even though I got K=3 for biological interpretation based on BIC, the membership plot derived from the Structure input file was different from those obtained from the other two file formats. The result using the Structure input format showed many admixture individuals, but the other two input files did not exhibit any admixture individuals (all with membership probability = 1). The latter makes sense to me because the fungus is asexual and genotype flow plays a main role in shaping population structure. Moreover, recombination is not possible for this fungus. Thus, admixture individuals may not occur. What caused this difference between these input files? How do I interpret these results? Thank you for your help.

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