To the Origin of Lake Baikal Endemic Gammarid Radiations, With Description of Two New Eulimnogammarus spp.

Extraordinarily diverse morphologically and ecologically, Lake Baikal\u27s two endemic gammaroidean amphipod clades are both firmly placed within the paraphyletic genus Gammarus, based both on morphological and molecular characters. However, the exact placement of the two Baikal clades remains elusive, making reconstruction of the ancestral state of Baikal endemic radiation difficult. We sequenced 2 mitochondrial and 3 nuclear genes from several species of each of the two clades aiming to represent early branches of the radiation. We also describe two new species of Baikal gammarids, Eulimnogammarus etingovae sp. nov. and Eulimnogammarus tchernykhi sp. nov., with some morphology suggestive of basal position within the radiation. We confirm the two previously demonstrated Baikal clades, but cannot unequivocally support any of the previous hypotheses about affinities of the two Baikal clades within palearctic Gammarus species. Rather, it appears that the two Baikal endemic radiations separated from the rest of freshwater Palearctic forms early and rapidly, probably as part of gammarid diversification during colonization of fresh waters in Middle Eocene

cog05361_NOP16

NOP16 gene alignment in Pallase

cog05812_MRPL22

MRPL22 gene alignment in Pallase

Hyall clade tree (nwk)

Hyall clade tree (nwk

Eulimno clade substitution statistics

Column names: cog, branch, #nonsyn_subst, #syn_subst, #nonsyn_sites, #syn_site

cog06250_AKR1

AKR1 gene alignment in Eulimn

cog05414_DNAJC11

DNAJC11 gene alignment in Pallase

Eulimno clade tree (nwk)

Eulimno clade tree (nwk

Hyall ckade substitution statistics

Column names: cog, branch, #nonsyn_subst, #syn_subst, #nonsyn_sites, #syn_site