title: Native fishes in the Truckee River: Are in-stream structures and patterns of population genetic structure related?
abstract: In-stream structures are recognized as significant impediments to movement for freshwater fishes. Apex predators such as salmonids have been the focus of much research on the impacts of such barriers to population dynamics and population viability however much less research has focused on native fishes, where in-stream structures may have a greater impact on long term population viability of these smaller, less mobile species. Patterns of genetic structure on a riverscape can provide information on which structures represent real barriers to movement for fish species and under what specific flow conditions. Here we characterize the impact of 41 dam and diversion structures on movement dynamics under varying flow conditions for a suite of six native fishes found in the Truckee River of California and Nevada. Microsatellite loci were used to estimate total allelic diversity, effective population size and assess genetic population structure. Although there is spatial overlap among species within the river there are clear differences in species distributions within the watershed. Observed population genetic structure was associated with in-stream structures, but only under low flow conditions. High total discharge in 2006 allowed fish to move over potential barriers resulting in no observed population genetic structure for any species in 2007. The efficacy of in-stream structures to impede movement and isolate fish emerged only after multiple years of low flow conditions. Our results suggest that restricted movement of fish species, as a result of in-stream barriers, can be mitigated by flow management. However, as flow dynamics are likely to be altered under global climate change, fragmentation due to barriers could isolate stream fishes into small subpopulations susceptible to both demographic losses and losses of genetic variation.
authors.affiliation: Department of Biology, University of Nevada-Reno, Reno, NV 89557, USA; Ecology, Evolution, and Conservation Biology Graduate Program, University of Nevada-Reno, Reno, NV 89557, USA. Electronic address: mpeacock@unr.edu.
authors.forename: Mary M
authors.initials: MM
authors.lastname: Peacock
authors.affiliation: Department of Natural Resources and Environmental Science, University of Nevada-Reno, Reno, NV 89557, USA.
authors.forename: Mae S
authors.initials: MS
authors.lastname: Gustin
authors.affiliation: Department of Biology, University of Nevada-Reno, Reno, NV 89557, USA.
authors.forename: Veronica S
authors.initials: VS
authors.lastname: Kirchoff
authors.affiliation: Department of Biology, University of Nevada-Reno, Reno, NV 89557, USA; Ecology, Evolution, and Conservation Biology Graduate Program, University of Nevada-Reno, Reno, NV 89557, USA.
authors.forename: Morgan L
authors.initials: ML
authors.lastname: Robinson
authors.affiliation: Department of Biological Sciences, Fordham University, New York, NY 10458, USA.
authors.forename: Evon
authors.initials: E
authors.lastname: Hekkala
authors.affiliation: Department of Natural Resources and Environmental Science, University of Nevada-Reno, Reno, NV 89557, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Pizzarro-Barraza
authors.affiliation: United States Fish and Wildlife Service, Lahontan National Fish Hatchery Complex, 710 Highway 395, Gardnerville, NV 89410, USA.
authors.forename: Tim
authors.initials: T
authors.lastname: Loux
mesh_terms: D063147:Animal Distribution; D000818:Animals; D044822:Biodiversity; D002140:California; D003247:Conservation of Natural Resources; D005399:Fishes / Q000502:physiology*; D014644:Genetic Variation; D009505:Nevada; D011157:Population Dynamics; D045483:Rivers; D014872:Water Movements
keywords: Bayesian genotype clustering analysis; Global climate change; Microsatellites; Stream flow