Researcher in statistical population genetics

Janek Sendrowski

Developing statistical methods and open-source software for inferring selection, demography and ancestry from genomic data.

PhD in Bioinformatics, Aarhus University Aarhus, Denmark

About

I am a population geneticist working at the interface of statistics, mathematics and software engineering. I recently completed my PhD in Bioinformatics at the Bioinformatics Research Centre, Aarhus University.

My research focuses on how natural selection and demographic history shape patterns of genomic variation, and how these processes can be inferred reliably from data. I have worked on estimating how new mutations affect fitness and on exact models of how sampled genomes trace back to common ancestors. I have also developed methods for inferring the ancestral state of genetic variants. More recently, my interest has extended to ancestral recombination graphs and to making genealogy-based inference robust to the imperfect data typical of non-model organisms.

Reproducible scientific software development is central to my work. I aim for methods that are efficient, well documented, thoroughly tested and openly available, so that others can build on them with confidence. I am also happy to get out of the office for field work, having sampled birch in Sweden and spruce in the Canadian Rockies.

Software

fastDFE

Distribution of fitness effects

Infers the distribution of fitness effects from site-frequency spectra, with joint inference across data sets, covariates and bootstrapping.

Python
R
conda-forge

$ conda install fastdfe

Documentation GitHub Paper

PhaseGen

Exact coalescent distributions

Exact coalescent distributions via phase-type theory, including time-varying demography, population structure, multiple mergers and two loci.

Python
R
conda-forge

$ conda install phasegen

Documentation GitHub Paper

SFSUtils

Site-frequency spectra from variant data

Builds site-frequency spectra from VCF, VCF-Zarr and tskit input, with ancestral-allele and degeneracy annotation, stratification and filtering.

Python
R
CLI
conda-forge

$ conda install sfsutils

Documentation GitHub Paper

Ancestree

Ancestral allele inference

Per-site posteriors over the ancestral allele from outgroups, a supplied ancestral recombination graph, or genealogies inferred from the genotypes alone.

Python
CLI
conda-forge

$ conda install ancestree

Documentation GitHub Paper

Publications

2026

Ancestree: unified likelihood inference of ancestral alleles under supplied or inferred genealogies

Sendrowski J, Bataillon T

bioRxiv

Preprint Software DOI

@article{sendrowski2026ancestree,
  title   = {Ancestree: unified likelihood inference of ancestral alleles under supplied or inferred genealogies},
  author  = {Sendrowski, Janek and Bataillon, Thomas},
  journal = {bioRxiv},
  year    = {2026},
  doi     = {10.64898/2026.09.11.750934}
}

2026

Comparison of the distribution of fitness effects across primates

Sendrowski J, Pedersen BM, Bergman J, Pankratov V, Bataillon T

Genetics

Accepted Comparative genomics DOI

@article{sendrowski2026primates,
  title   = {Comparison of the Distribution of Fitness Effects Across Primates},
  author  = {Sendrowski, Janek and Pedersen, Bjarke M. and Bergman, Juraj and Pankratov, Vasili and Bataillon, Thomas},
  journal = {Genetics},
  note    = {Accepted. Preprint on bioRxiv},
  year    = {2026},
  doi     = {10.64898/2026.03.25.714151}
}

2026

Inference of the distribution of fitness effects and its genomic covariates from site frequency spectrum data using fastDFE

Sendrowski J, Bataillon T

In Statistical Population Genomics, 2nd edition. Springer

Book chapter In print Tutorial

2026

Replicated hybrid zones reveal genomic patterns of local adaptation and introgression in spruce

Nocchi G, Sendrowski J, Shi A, Boufford B, Lamothe M, Isabel N, Yeaman S

Molecular Biology and Evolution 43(4): msag074

Local adaptation DOI

@article{nocchi2026spruce,
  title   = {Replicated hybrid zones reveal genomic patterns of local adaptation and introgression in spruce},
  author  = {Nocchi, Gabriele and Sendrowski, Janek and Shi, Andy and Boufford, Brianne and Lamothe, Manuel and Isabel, Nathalie and Yeaman, Sam},
  journal = {Molecular Biology and Evolution},
  volume  = {43},
  number  = {4},
  pages   = {msag074},
  year    = {2026},
  doi     = {10.1093/molbev/msag074}
}

2025

PhaseGen: exact solutions for time-inhomogeneous multivariate coalescent distributions under diverse demographies

Sendrowski J, Hobolth A

Genetics 232(1): iyaf135

Software DOI

@article{sendrowski2025phasegen,
  title   = {PhaseGen: exact solutions for time-inhomogeneous multivariate coalescent distributions under diverse demographies},
  author  = {Sendrowski, Janek and Hobolth, Asger},
  journal = {Genetics},
  volume  = {232},
  number  = {1},
  pages   = {iyaf135},
  year    = {2025},
  doi     = {10.1093/genetics/iyaf135}
}

2025

In silico prediction of variant effects: promises and limitations for precision plant breeding

Sendrowski J, Bataillon T, Ramstein GP

Theoretical and Applied Genetics 138: 193

Review DOI

@article{sendrowski2025insilico,
  title   = {In silico prediction of variant effects: promises and limitations for precision plant breeding},
  author  = {Sendrowski, Janek and Bataillon, Thomas and Ramstein, Guillaume P.},
  journal = {Theoretical and Applied Genetics},
  volume  = {138},
  number  = {8},
  pages   = {193},
  year    = {2025},
  doi     = {10.1007/s00122-025-04973-1}
}

2024

fastDFE: fast and flexible inference of the distribution of fitness effects

Sendrowski J, Bataillon T

Molecular Biology and Evolution 41(5): msae070

Software DOI

@article{sendrowski2024fastdfe,
  title   = {fastDFE: Fast and Flexible Inference of the Distribution of Fitness Effects},
  author  = {Sendrowski, Janek and Bataillon, Thomas},
  journal = {Molecular Biology and Evolution},
  volume  = {41},
  number  = {5},
  pages   = {msae070},
  year    = {2024},
  doi     = {10.1093/molbev/msae070}
}

2022

Teasing apart the joint effect of demography and natural selection in the birth of a contact zone

Li L, Milesi P, Tiret M, Chen J, Sendrowski J, Baison J, Chen Z, Zhou L, Karlsson B, Berlin M, Westin J, Garcia-Gil MR, Wu HX, Lascoux M

New Phytologist 236(5): 1976–1987

Demography DOI

@article{li2022contact,
  title   = {Teasing apart the joint effect of demography and natural selection in the birth of a contact zone},
  author  = {Li, Lili and Milesi, Pascal and Tiret, Mathieu and Chen, Jun and Sendrowski, Janek and Baison, John and Chen, Zhi-qiang and Zhou, Linghua and Karlsson, Bo and Berlin, Mats and Westin, Johan and Garcia-Gil, Maria Rosario and Wu, Harry X. and Lascoux, Martin},
  journal = {New Phytologist},
  volume  = {236},
  number  = {5},
  pages   = {1976--1987},
  year    = {2022},
  doi     = {10.1111/nph.18480}
}

Background

2023 – 2026
PhD in Bioinformatics, Aarhus University, Denmark
Bioinformatics Research Centre. Supervised by Thomas Bataillon and Asger Hobolth.
2021 – 2023
MSc in Bioinformatics, Uppsala University, Sweden
With Martin Lascoux, Department of Ecology and Genetics.
2015 – 2020
BSc in Applied Mathematics, Linnaeus University, Sweden
2013 – 2017
Full-stack developer, excogitat GmbH, Germany
Developed a web platform for sharing and searching translation memories among translators.