Volcano-tectonic processes have been viewed as primary divers in the formation of present-day diversity. Volcanos associated with mountain uplifts drives allopatric speciation through vicariance and may impact the surrounding areas like species pump or species attractor. However, the application of these hypotheses to aquatic fauna has rarely been tested explicitly. We conducted this research in the Changbai Mountains (Mts), which are one of the most typical, active volcanic ranges in Northeast (NE) Asia with a long and turbulent geological history. The Gammarus nekkensis species complex of amphipod crustaceans, widely distributed throughout NE Asia with poor dispersal abilities and a long evolutionary history, is a suitable model for testing these hypotheses. Phylogenetic and ancestral range reconstructions demonstrated that the studied amphipod originated from the Changbai Mts approximately 27 Ma and diverged into eastern (Clade I) and western (Clade II) clades, which corresponds well with the initial volcanic eruption of the Changbai Mts in the Late Oligocene. The subsequent diversifications of subclades CI-3, CII-1a and CII-2a were likely driven by second and third eruptions of the Changbai Mts during the Miocene. In particular, the Changbai lineages had spread to the Russian Far East multiple times since the Early Miocene, and widely colonized the region during the Pleistocene. Our discoveries suggest that the ancient volcanos of the Changbai Mts act as species pumps in NE Asia, resulted in burst of diversification around the Changbai Mts and subsequent dispersals into adjacent regions.

Alignments

Aligned sequences of the five genes used in analysis

R scripts used in this analysis

The r scripts about bGMYC, LTT, Laser, BioGeoBEARS, GeoSSE

Trees

All trees generated for the publication in editable formats (nexus and newick).

1.Figure 2 The species-level Maximum clade credibility tree from the BEAST analysis

2.The 1000 species-level time-calibrated trees with outgroups removed from the BEAST analysis

4.Multiple-gene phylogeny based on the BI analysis in MrBayes.

5.Multiple-gene phylogeny based on the ML analysis in RAxML.