Within-river genetic connectivity patterns reflect contrasting geomorphology

Abstract

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 φST=0.696) than within greywacke (n=10; meanφST=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.