RT Journal Article SR Electronic T1 Exact calculation of the expected SFS in structured populations JF bioRxiv FD Cold Spring Harbor Laboratory SP 2023.05.10.540112 DO 10.1101/2023.05.10.540112 A1 Armando Arredondo A1 Josué Corujo A1 Camille Noûs A1 Simon Boitard A1 Lounès Chikhi A1 Olivier Mazet YR 2023 UL http://biorxiv.org/content/early/2023/05/12/2023.05.10.540112.abstract AB The Site Frequency Spectrum (SFS), summary statistic of the distribution of derived allele frequencies in a sample of DNA sequences, provides information about genetic variation and can be used to make population inferences. The exact calculation of the expected SFS in panmictic population has been derived in the Markovian coalescent theory for decades, but its generalization to the structured coalescent is hampered by the almost exponential growth of the states space. We propose here a complete algorithmic procedure, from how to build a suitable state space and sort it, to how to take advantage of the sparsity of the rate matrix and to solve numerically the linear system by an iterative method. The simplest case of the symmetrical n-island is then processed to arrive at a ready-to-use demographic parameters inference framework.Competing Interest StatementThe authors have declared no competing interest.