Within-river genetic connectivity patterns reflect contrasting geomorphology

Aim

To test the hypothesis that geomorphological features, shaped by underlying geology, can influence within-river connectivity patterns in freshwater-limited fishes.

Location

Rivers draining the eastern flanks of the Southern Alps in South Island, New Zealand.

Methods

We analyse up to 1624 bp of mtDNA from 499 ‘flathead’ Galaxias specimens from 145 localities across 14 different river systems. Variation among sampling sites within systems is characterized using ϕ statistics.

Results

Although similar levels of DNA sequence variation were detected in all rivers sampled, spatial partitioning of this variation was significantly greater within schist (n = 5; mean ϕ_ST = 0.696) than within greywacke (n = 10; mean ϕ_ST = 0.268) rivers.

Main conclusions

Population connectivity can be strongly influenced by underlying geology, leading to profound differences in the connectivity, phylogeography and diversity of riverine species.