Abstract
AbstractInformed conservation of stream fishes requires detailed understanding of the effects of both natural processes and anthropogenic activities on genetic diversity. Brook Trout Salvelinus fontinalis, a salmonid native to eastern North America, typically resides in cold, high‐quality stream ecosystems. The species has not only faced historical anthropogenic pressures, but also confronts current and future pressures. In a genetic analysis we used a reduced representation sequencing method (ddRADseq) to characterize 63 individuals from 23 streams where Brook Trout are native in the Appalachian region of Pennsylvania. A total of 2,590 loci passed filtering criteria, and 53% displayed significant association with a major stream drainage basin (Susquehanna or Allegheny; mean FST = 0.085). Mapping of the sequencing reads to the Atlantic Salmon Salmo salar genome revealed no clustering of high interdrainage FST values to specific genome regions. Evidence for genetic heterogeneity within each drainage basin was also detected. Stepwise regression of observed heterozygosity against geographic and environmental features revealed that drainage basin and effective area of watersheds were significant predictors of observed heterozygosity of Brook Trout within streams. Natural features such as waterfalls and major drainage basin, as well as the effects of dams and acid‐mine drainage have fragmented habitat and shaped genetic diversity within Brook Trout populations in the Appalachian region of Pennsylvania, overall indicating the vulnerability of this species to increased industrialization.Received August 15, 2016; accepted January 17, 2017 Published online March 24, 2017
Highlights
Connectivity of freshwater fishes in the northeastern United States is affected by many natural and anthropogenic environmental challenges such as drainage from abandoned coal mines, hydroelectric dams, and natural gas development
Landscape structure has shaped Brook Trout population structure in Maine and Québec where a significant negative relationship has been found between mean heterozygosity and altitude, and significant variance in genetic structure has been explained by drainage basin structure (Castric et al 2001)
Previous studies have hypothesized that unexplained variance in genomic data among Brook Trout populations may be due to habitat quality influencing population structure and is related to habitat selection by anadromous individuals returning from sea (Rogers and Curry 2004)
Summary
Connectivity of freshwater fishes in the northeastern United States is affected by many natural and anthropogenic environmental challenges such as drainage from abandoned coal mines, hydroelectric dams, and natural gas development (i.e., fracking). Over 5,000 km (3,000 mi) of stream waters in Pennsylvania (Pennsylvania Water Science Center, unpublished data) and over 10% of streams in the Appalachian region (Herlihy et al 1990) are affected by AMD Hydroelectric dams are another anthropogenic challenge known to fragment aquatic communities by limiting movement of fish upstream or downstream from dams and between watersheds (Morita and Yamamoto 2002). Fracking has grown exponentially in the northeastern United States, and over 60,000 wells are projected to be developed in Pennsylvania alone by 2030 (Johnson 2010) Both withdrawal of water from streams for fracking and effluent spills from fracking have the ability to significantly alter stream physiochemical dynamics (Entrekin et al 2011; Weltman-Fahs and Taylor 2013) and presumably alter fish passage and connectivity. Compared with traditional batteries of a dozen microsatellite markers, for example, a panel of thousands of singlenucleotide polymorphism (SNP) loci distributed throughout the genome provides an increased resolution of population structure and an ability to find loci under the influence of selection
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