Data from: Genetic signs of multiple colonization events in Baltic ciscoes with radiation into sympatric spring and autumn-spawners confined to early post-glacial arrival

Presence of sympatric populations may reflect local diversification or
secondary contact of already distinct forms. The Baltic cisco (Coregonus
albula) normally spawns in late autumn, but in a few lakes in Northern
Europe sympatric autumn and spring- or winter-spawners have been
described. So far, the evolutionary relationships and taxonomic status of
these main life history forms have remained largely unclear. With
microsatellites and mtDNA sequences, we analyzed extant and extinct
spring- and autumn-spawners from a total of 23 Swedish localities,
including sympatric populations. Published sequences from Baltic ciscoes
in Germany and Finland, and Coregonus sardinella from North America were
also included together with novel mtDNA sequences from Siberian C.
sardinella. A clear genetic structure within Sweden was found that
included two population assemblages markedly differentiated at
microsatellites and apparently fixed for mtDNA haplotypes from two
distinct clades. All sympatric Swedish populations belonged to the same
assemblage, suggesting parallel evolution of spring-spawning rather than
secondary contact. The pattern observed further suggests that postglacial
immigration to Northern Europe occurred from at least two different
refugia. Previous results showing that mtDNA in Baltic cisco is
paraphyletic with respect to North American C. sardinella were confirmed.
However, the inclusion of Siberian C. sardinella revealed a more
complicated pattern, as these novel haplotypes were found within one of
the two main C. albula clades and were clearly distinct from those in
North American C. sardinella. The evolutionary history of Northern
Hemisphere ciscoes thus seems to be more complex than previously
recognized.