A new, lightning fast implementation of ADMIXTOOLS.
ADMIXTOOLS is a collection of programs which use genetic data to infer how populations are related to one another. It has been used in countless publications to test whether populations form clades (qpDstat, qpWave), to estimate ancestry proportions (qpAdm), and to fit admixture graphs (qpGraph).
ADMIXTOOLS 2 provides the same functionality as ADMIXTOOLS in a new look, and it’s orders of magnitude faster. This is achieved through separating the computation of f2-statistics from all other computations, and through a number of other optimizations. In the example below, rendering the plot takes much longer than computing the fit of a new qpGraph model:
ADMIXTOOLS 2 is currently still under active development. Most of it has already been tested extensively, but functionality is still added and may change here and there. ADMIXTOOLS 2 is not yet on the CRAN servers (so you can’t install it with
install.packages()), but you can install it from github with the following commands (provided you have R version 3.5 or higher):
install.packages("devtools") # if "devtools" is not installed already devtools::install_github("uqrmaie1/admixtools") library("admixtools")
The above commands will install all R package dependencies which are required to run ADMIXTOOLS 2 on the command line. For the interactive app, additional packages are required, which can be installed like this:
devtools::install_github("uqrmaie1/admixtools", dependencies = TRUE)
If you encounter any problems during the installation, this is most likely because some of the required R packages cannot be installed. If that happens, try manually re-installing some of the larger packages, and pay attention to any error message:
install.packages("Rcpp") install.packages("tidyverse") install.packages("igraph") install.packages("plotly")
If you get the following error:
Error: Failed to install 'admixtools' from GitHub: Could not find tools necessary to compile a package.
On some Linux distributions, it may be necessary to manually install additional libraries or programs. For example, if you see the error
gfortran: command not found during installation, you would have to install
sudo zypper in gfortran or
sudo apt-get install gfortran, depending on the Linux distribution.
If you get any other errors during installation, please contact me.
Admixture graphs can be fitted like this:
genotype_data = "/my/geno/prefix" fit = qpgraph(genotype_data, example_graph) fit$score
#>  19219.98
Clearly not a historically accurate model, but it gets the idea across.
When testing more than one model, it makes sense to extract and re-use f2-statistics:
fit$score #>  19219.98
f2-statistics can also be used to estimate admixture weights:
qpadm(f2_blocks, left, right, target)$weights
#> # A tibble: 2 x 5 #> target left weight se z #> <chr> <chr> <dbl> <dbl> <dbl> #> 1 Denisova.DG Altai_Neanderthal.DG 49.6 23.3 2.13 #> 2 Denisova.DG Vindija.DG -48.6 23.3 -2.08
Or to get f4-statistics:
#> # A tibble: 105 x 8 #> pop1 pop2 pop3 pop4 est se z p #> <chr> <chr> <chr> <chr> <dbl> <dbl> <dbl> <dbl> #> 1 Altai_Nean… Chimp.REF Deniso… Mbuti.DG 0.0196 6.07e-4 32.4 1.32e-229 #> 2 Altai_Nean… Denisova.DG Chimp.… Mbuti.DG -0.0129 3.64e-4 -35.6 2.22e-277 #> 3 Altai_Nean… Mbuti.DG Chimp.… Denisova.DG -0.0326 5.22e-4 -62.5 0. #> 4 Altai_Nean… Chimp.REF Deniso… Russia_Ust… 0.0180 6.87e-4 26.3 6.43e-152 #> 5 Altai_Nean… Denisova.DG Chimp.… Russia_Ust… -0.0152 4.46e-4 -34.0 4.67e-254 #> 6 Altai_Nean… Russia_Ust_… Chimp.… Denisova.DG -0.0332 5.55e-4 -60.0 0. #> 7 Altai_Nean… Chimp.REF Deniso… Switzerlan… 0.0181 6.63e-4 27.3 1.09e-164 #> 8 Altai_Nean… Denisova.DG Chimp.… Switzerlan… -0.0150 4.64e-4 -32.3 6.06e-229 #> 9 Altai_Nean… Switzerland… Chimp.… Denisova.DG -0.0331 5.74e-4 -57.7 0. #> 10 Altai_Nean… Chimp.REF Deniso… Vindija.DG -0.0771 6.98e-4 -110. 0. #> # … with 95 more rows
ADMIXTOOLS 2 also has a simple point-and-click interface. This makes it easy to explore many qpAdm or qpGraph models at the same time, for example by allowing you to build and change admixture graphs interactively. Typing the following command in the R console launches the app:
One of the design goals behind ADMIXTOOLS 2 is to make the algorithms more transparent, so that the steps leading from from genotype data to conclusions about demographic history are easier to follow.
To this end, all ADMIXTOOLS 2 functions are documented. You can also take a look at the tutorial, read more about how ADMIXTOOLS 2 computes f-statistics and standard errors, and what you can do with admixture graphs.
For even greater transparency, many of the core functions are implemented twice: In C++ for performance (used by default), and in R, which makes it easier to trace the computations step by step. For example, if you want to know how weights are computed in
qpadm(), you can type
qpadm in R to get the function code and you will see another function which is called
qpadm_weights(). By default, this function will be replaced by its faster C++ version
cpp_qpadm_weights(). But you can still see what it’s doing without reading the C++ code by typing
admixtools:::qpadm_weights. And you can tell
qpadm() to use the R versions instead of the C++ versions by calling
qpadm(cpp = FALSE).
For questions, feature requests, and bug reports, please contact Robert Maier under firstname.lastname@example.org.
If you wish to cite ADMIXTOOLS 2, you can link to this website and mention that a manuscript describing ADMIXTOOLS 2 is currently under preparation.