msABC: a modification of Hudson's ms to facilitate multi-locus ABC analysis

With the availability of whole-genome sequence data biologists are able to test hypotheses regarding the demography of populations. Furthermore, the advancement of the Approximate Bayesian Computation (ABC) methodology allows the demographic inference to be performed in a simple framework using summary statistics. We present here msABC, a coalescent-based software that facilitates the simulation of multi-locus data, suitable for an ABC analysis. msABC is based on Hudson's ms algorithm, which is used extensively for simulating neutral demographic histories of populations. The flexibility of the original algorithm has been extended so that sample size may vary among loci, missing data can be incorporated in simulations and calculations, and a multitude of summary statistics for single or multiple populations is generated. The source code of msABC is available at http://bio.lmu.de/~pavlidis/msabc or upon request from the authors.     

DnaSAM: Software to perform neutrality testing for large datasets with complex null models

Patterns of DNA sequence polymorphisms can be used to understand the processes of demography and adaptation within natural populations. High-throughput generation of DNA sequence data has historically been the bottleneck with respect to data processing and experimental inference. Advances in marker technologies have largely solved this problem. Currently, the limiting step is computational, with most molecular population genetic software allowing a gene-by-gene analysis through a graphical user interface. An easy-to-use analysis program that allows both high-throughput processing of multiple sequence alignments along with the flexibility to simulate data under complex demographic scenarios is currently lacking. We introduce a new program, named DnaSAM, which allows high-throughput estimation of DNA sequence diversity and neutrality statistics from experimental data along with the ability to test those statistics via Monte Carlo coalescent simulations. These simulations are conducted using the ms program, which is able to incorporate several genetic parameters (e.g. recombination) and demographic scenarios (e.g. population bottlenecks). The output is a set of diversity and neutrality statistics with associated probability values under a user-specified null model that are stored in easy to manipulate text file.     

gmconvert: file conversion for genemapper output files

gmconvert is a platform‐independent program provided in GUI (for Apple OS X and Windows XP) and command‐line versions (for other platforms). gmconvert allows rapid reformatting of microsatellite data from output files produced by Applied Biosystems genemapper software (version 3.x). The program will re‐array data into three formats commonly used in downstream analysis: genepop , cervus , and gerud . gmconvert will greatly increase the speed of data preparation prior to analysis and aid in reducing transpositional errors associated with manual re‐arraying and reformatting steps. gmconvert is available from http://gallus.forestry.uga.edu/software/ .     

New softwares for automated microsatellite marker development

Microsatellites are repeated small sequence motifs that are highly polymorphic and abundant in the genomes of eukaryotes. Often they are the molecular markers of choice. To aid the development of microsatellite markers we have developed a module that integrates a program for the detection of microsatellites (TROLL), with the sequence assembly and analysis software, the Staden Package. The module has easily adjustable parameters for microsatellite lengths and base pair quality control. Starting with large datasets of unassembled sequence data in the form of chromatograms and/or text data, it enables the creation of a compact database consisting of the processed and assembled microsatellite containing sequences. For the final phase of primer design, we developed a program that accepts the multi-sequence ‘experiment file’ format as input and produces a list of primer pairs for amplification of microsatellite markers. The program can take into account the quality values of consensus bases, improving success rate of primer pairs in PCR. The software is freely available and simple to install in both Windows and Unix-based operating systems. Here we demonstrate the software by developing primer pairs for 427 new candidate markers for peanut.     

combi.pl: a computer program to combine data sets with inconsistent microsatellite marker allele size information

Combining two data sets with allele information from overlapping microsatellite markers is often desirable, particularly in population genetic studies where a substantial body of published data exists. When genotyping is performed in different laboratories, allele size calling may not be presumed to be consistent. Our approach solves this problem by assigning allele sizes across studies using maximum-likelihood theory. Using data overlaps in samples and markers, allele shifts between two studies are calculated for each overlapping marker and a single file containing allele frequencies of consistent alleles is produced. The program (combi.pl) is written in PERL and available at http://data40.uni-tz.gwdg.de/~htaeube.     

CAPS: coevolution analysis using protein sequences

Coevolution Analysis using Protein Sequences (CAPS) is a PERL based software that identifies co-evolution between amino acid sites. Blosum-corrected amino acid distances are used to identify amino acid co-variation. The phylogenetic sequence relationships are used to remove the phylogenetic and stochastic dependencies between sites. The 3D protein structure is used to identify the nature of the dependencies between co-evolving amino acid sites. Friendly interpretable output files are generated. AVAILABILITY: CAPS version 1 is available at http://bioinf.gen.tcd.ie/~faresm/software/caps/. Distribution versions for Linux/Unix, Mac OS X and Windows operating systems are available, including manual and example files.     

Redundancy based detection of sequence polymorphisms in expressed sequence tag data using autoSNP

AutoSNP is a program to detect single nucleotide polymorphisms (SNPs) and insertion/deletion polymorphisms (indels) in expressed sequence tag (EST) data. The program uses d2cluster and cap3 to cluster and align EST sequences, and uses redundancy to differentiate between candidate SNPs and sequence errors. Candidate polymorphisms are identified as occurring in multiple reads within an alignment. For each candidate SNP, two measures of confidence are calculated, the redundancy of the polymorphism at a SNP locus and the co segregation of the candidate SNP with other SNPs in the alignment. AVAILABILITY: The program was written in PERL and is freely available to non-commercial users by request from the authors.     

Critical assessment of coalescent simulators in modeling recombination hotspots in genomic sequences

Background

Coalescent simulation is pivotal for understanding population evolutionary models and demographic histories, as well as for developing novel analytical methods for genetic association studies for DNA sequence data. A plethora of coalescent simulators are developed, but selecting the most appropriate program remains challenging.

Results

We extensively compared performances of five widely used coalescent simulators – Hudson’s ms, msHOT, MaCS, Simcoal2, and fastsimcoal, to provide a practical guide considering three crucial factors, 1) speed, 2) scalability and 3) recombination hotspot position and intensity accuracy. Although ms represents a popular standard coalescent simulator, it lacks the ability to simulate sequences with recombination hotspots. An extended program msHOT has compensated for the deficiency of ms by incorporating recombination hotspots and gene conversion events at arbitrarily chosen locations and intensities, but remains limited in simulating long stretches of DNA sequences. Simcoal2, based on a discrete generation-by-generation approach, could simulate more complex demographic scenarios, but runs comparatively slow. MaCS and fastsimcoal, both built on fast, modified sequential Markov coalescent algorithms to approximate standard coalescent, are much more efficient whilst keeping salient features of msHOT and Simcoal2, respectively. Our simulations demonstrate that they are more advantageous over other programs for a spectrum of evolutionary models. To validate recombination hotspots, LDhat 2.2 rhomap package, sequenceLDhot and Haploview were compared for hotspot detection, and sequenceLDhot exhibited the best performance based on both real and simulated data.

Conclusions

While ms remains an excellent choice for general coalescent simulations of DNA sequences, MaCS and fastsimcoal are much more scalable and flexible in simulating a variety of demographic events under different recombination hotspot models. Furthermore, sequenceLDhot appears to give the most optimal performance in detecting and validating cross-over hotspots.     

AQUASPLATCHE: a program to simulate genetic diversity in populations living in linear habitats

Classical models of structured populations do not apply well to species leaving in semilinear habitats such as freshwater fishes, since these habitats are intermediate between one‐dimensional and two‐dimensional stepping‐stone models. In order to investigate the genetic diversity of such populations, we have developed a new simulation program called aquasplatche . It starts by dividing a user‐defined vectorized network into segments of arbitrary length, each segment hosting a single deme. The program then proceeds by simulating the colonization of the environment from an arbitrary source, recording the evolution of the deme densities and the migration events between adjacent demes over time. This demographic history is then used to generate genetic data of population samples located in various segments of the network, using a backward coalescent framework. Different versions of aquasplatche are freely available on http://cmpg.unibe.ch/software/aquasplatche .     

The automation of Nested Clade Phylogeographic Analysis

ANeCA is a fully automated implementation of Nested Clade Phylogeographic Analysis. This was originally developed by Templeton and colleagues, and has been used to infer, from the pattern of gene sequence polymorphisms in a geographically structured population, the historical demographic processes that have shaped its evolution. Until now it has been necessary to perform large parts of the procedure manually. We provide a program that will take data in Nexus sequential format, and directly output a set of inferences. The software also includes TCS v1.18 and GeoDis v2.2 as part of automation. Availability: The software is available free of charge from http://www.rubic.rdg.ac.uk/~mahesh/software.html. The program is written in Java and requires the Java 1.4 Runtime Environment (or later) to run. The source code is included in the package, and includes the source from TCS and GeoDis. ANeCA, TCS and GeoDis are released under the GNU General Public License.     

MICROSATELIGHT--pipeline to expedite microsatellite analysis

MICROSATELIGHT is a Perl/Tk pipeline with a graphical user interface that facilitates several tasks when scoring microsatellites. It implements new subroutines in R and PERL and takes advantage of features provided by previously developed freeware. MICROSATELIGHT takes raw genotype data and automates the peak identification through PeakScanner. The PeakSelect subroutine assigns peaks to different microsatellite markers according to their multiplex group, fluorochrome type, and size range. After peak selection, binning of alleles can be carried out 1) automatically through AlleloBin or 2) by manual bin definition through Binator. In both cases, several features for quality checking and further binning improvement are provided. The genotype table can then be converted into input files for several population genetics programs through CREATE. Finally, Hardy-Weinberg equilibrium tests and confidence intervals for null allele frequency can be obtained through GENEPOP. MICROSATELIGHT is the only freely available public-domain software that facilitates full multiplex microsatellite scoring, from electropherogram files to user-defined text files to be used with population genetics software. MICROSATELIGHT has been created for the Windows XP operating system and has been successfully tested under Windows 7. It is available at http://sourceforge.net/projects/microsatelight/.     

WebSat ‐ A web software for microsatellite marker development

Simple sequence repeats (SSR), also known as microsatellites, have been extensively used as molecular markers due to their abundance and high degree of polymorphism. We have developed a simple to use web software, called WebSat, for microsatellite molecular marker prediction and development. WebSat is accessible through the Internet, requiring no program installation. Although a web solution, it makes use of Ajax techniques, providing a rich, responsive user interface. WebSat allows the submission of sequences, visualization of microsatellites and the design of primers suitable for their amplification. The program allows full control of parameters and the easy export of the resulting data, thus facilitating the development of microsatellite markers.