Table S5.

Formulation of the four main divergence scenarios

Scenario no.	Scenario identity
1	Independent-introductions scenario: a single split of the Baltic demersal population from the North Sea followed by another, independent single split of the Baltic pelagic population from the North Sea
2	Single-invasion scenario: a single split of the Baltic pelagic population from the North Sea, followed by a single split of the Baltic demersal from the Baltic pelagic population
3	Alternative single-invasion scenario: a single split of the Baltic demersal population from the North Sea, followed by a single split of the Baltic pelagic from the Baltic demersal population
4	Alternative independent-introductions scenario: a single split of the Baltic pelagic population from the North Sea followed by another, independent single split of the Baltic demersal population from the North Sea