Parsimoniously reconstructed genealogies of sample WS ( M. edulis , North Sea) and sample LU ( M. edulis , Bay of Biscay). Mutations are indicated with dots. The single sequence belonging to the B clade sampled in an individual from LU as a result of introgression was used to root genealogies but was not represented and was excluded from the analyses. Interpretations of sample genealogies under the hypothesis of a selective sweep are presented in terms of descendants of the swept allele versus ancestral lineages that survived to the sweep through recombination. The results of the likelihood ratio test  and estimations of the age, T, and the strength, S, of the sweep are given below genealogies.