Present address: Center for the Management, Utilization and Protection of Water Resources and Department of Biology, Tennessee Technological University, Box 5063, 1100 North Dixie Avenue, Cookeville, TN 38505, USA.
Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks
Article first published online: 8 AUG 2011
© 2011 Blackwell Publishing Ltd
Volume 20, Issue 18, pages 3711–3729, September 2011
How to Cite
KANNO, Y., VOKOUN, J. C. and LETCHER, B. H. (2011), Fine-scale population structure and riverscape genetics of brook trout (Salvelinus fontinalis) distributed continuously along headwater channel networks. Molecular Ecology, 20: 3711–3729. doi: 10.1111/j.1365-294X.2011.05210.x
- Issue published online: 8 SEP 2011
- Article first published online: 8 AUG 2011
- Received 27 December 2010; revision received 8 June 2011; accepted 16 June 2011
- genetic clusters;
- landscape genetics;
- Salvelinus fontinalis;
Linear and heterogeneous habitat makes headwater stream networks an ideal ecosystem in which to test the influence of environmental factors on spatial genetic patterns of obligatory aquatic species. We investigated fine-scale population structure and influence of stream habitat on individual-level genetic differentiation in brook trout (Salvelinus fontinalis) by genotyping eight microsatellite loci in 740 individuals in two headwater channel networks (7.7 and 4.4 km) in Connecticut, USA. A weak but statistically significant isolation-by-distance pattern was common in both sites. In the field, many tagged individuals were recaptured in the same 50-m reaches within a single field season (summer to fall). One study site was characterized with a hierarchical population structure, where seasonal barriers (natural falls of 1.5–2.5 m in height during summer base-flow condition) greatly reduced gene flow and perceptible spatial patterns emerged because of the presence of tributaries, each with a group of genetically distinguishable individuals. Genetic differentiation increased when pairs of individuals were separated by high stream gradient (steep channel slope) or warm stream temperature in this site, although the evidence of their influence was equivocal. In a second site, evidence for genetic clusters was weak at best, but genetic differentiation between individuals was positively correlated with number of tributary confluences. We concluded that the population-level movement of brook trout was limited in the study headwater stream networks, resulting in the fine-scale population structure (genetic clusters and clines) even at distances of a few kilometres, and gene flow was mitigated by ‘riverscape’ variables, particularly by physical barriers, waterway distance (i.e. isolation-by-distance) and the presence of tributaries.