Status and Conservation of Interior Redband Trout in the Western United States

<div><p></p><p>In this article we describe the current status and conservation of interior (potamodromous) Redband Trout <i>Oncorhynchus mykiss</i> sspp. throughout its range in the western United States using extant data and expert opinion provided by fish managers. Redband Trout historically occupied 60,295 km of stream habitat and 152 natural lakes. Currently, Redband Trout occupy 25,417 km of stream habitat (42% of their historical range) and 124 lakes or reservoirs. Nonhybridized populations are assumed to occupy 11,695 km (46%) of currently occupied streams; however, fish from only 4,473 km (18%) have been genetically tested. Approximately 47% of the streams occupied by Redband Trout occur on private land, 45% on government lands, and 8% in protected areas. A total of 210 Redband Trout populations, occupying 15,252 km of stream habitat (60% of the current distribution) and 95,158 ha of lake habitat (52%), are being managed as “conservation populations.” Most conservation populations have been designated as weakly to strongly connected metapopulations (125; 60%) and occupy much more stream length (14,112 km; 93%) than isolated conservation populations (1,141 km; 7%). The primary threats to Redband Trout include invasive species, habitat degradation and fragmentation, and climate change. Although the historical distribution of interior Redband Trout has declined dramatically, we conclude that the species is not currently at imminent risk of extinction because it is still widely distributed with many populations isolated by physical barriers and active conservation efforts are occurring for many populations. However, the hybridization status of many populations has not been well quantified, and introgression may be more prevalent than documented here. We recommend (1) collecting additional genetic data and estimating distribution and abundance by means of a more rigorous spatial sampling design to reduce uncertainties, (2) collecting additional information to assess and predict the impacts of climate on populations, and (3) continuing to use this database to evaluate the status of Redband Trout and inform conservation efforts through time.</p><p>Received March 21, 2014; accepted August 1, 2014</p></div

Kovach_etal_WCTRBT_hybridization

The excel file contains the genotypic data for all individual trout (Oncorhynchus) that were sampled from 2003 - 2007. Fish were genotyped at 8 species diagnostic microsatellite loci. Columns D-S are the raw allele lengths, while columns T - AI describe whether each allele at each locus is of westslope cutthroat trout ancestry (denoted by 0) or rainbow trout ancestry (denoted by 1). Other descriptive columns include individual ID, maturity (spawning adult or outmigrating juvenile), date captured (i.e., migration date), length (in mm), and age (for Langford juveniles only). Data for Langford and Cyclone are on two separate sheets

Summary of results from population genetic analyses.

<p>Summary of results from population genetic analyses.</p

Minimum-spanning haplotype network for concatenated COI and CytB data from 116 <i>Lednia tumana</i> individuals.

<p>Individual haplotype colors correspond to those in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157386#pone.0157386.g001" target="_blank">Fig 1</a>.</p

Sampling and demographic information for 116 <i>Lednia tumana</i> individuals.

<p>Shaded boxes indicate adjacent sites that were pooled for combined analysis, and the Combined n refers to the combined totals of those sites.</p

Estimates of G_st analog 95% confidence intervals from SMOGD [29] for historic and 2010 populations of <i>L</i>. <i>tumana</i>.

<p>Estimates of G_st analog 95% confidence intervals from SMOGD [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157386#pone.0157386.ref029" target="_blank">29</a>] for historic and 2010 populations of <i>L</i>. <i>tumana</i>.</p

Loss of Genetic Diversity and Increased Subdivision in an Endemic Alpine Stonefly Threatened by Climate Change - Fig 3

<p><b>Gene (A), nucleotide (B), and allelic (C) diversity for populations of three species of Plecoptera.</b> Allelic diversity was estimated using the rarefaction method implemented in HP-RARE [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157386#pone.0157386.ref028" target="_blank">28</a>].</p

Genetic Status and Conservation of Westslope Cutthroat Trout in Glacier National Park

<p>Invasive hybridization is one of the greatest threats to the persistence of Westslope Cutthroat Trout <i>Oncorhynchus clarkii lewisi</i>. Large protected areas, where nonhybridized populations are interconnected and express historical life history and genetic diversity, provide some of the last ecological and evolutionary strongholds for conserving this species. Here, we describe the genetic status and distribution of Westslope Cutthroat Trout throughout Glacier National Park, Montana. Admixture between Westslope Cutthroat Trout and introduced Rainbow Trout <i>O. mykiss</i> and Yellowstone Cutthroat Trout <i>O. clarkii bouvieri</i> was estimated by genotyping 1,622 fish collected at 115 sites distributed throughout the Columbia, Missouri, and South Saskatchewan River drainages. Currently, Westslope Cutthroat Trout occupy an estimated 1,465 km of stream habitat and 45 lakes (9,218 ha) in Glacier National Park. There was no evidence of introgression in samples from 32 sites along 587 km of stream length (40% of the stream kilometers currently occupied) and 17 lakes (2,555 ha; 46% of the lake area currently occupied). However, nearly all (97%) of the streams and lakes that were occupied by nonhybridized populations occurred in the Columbia River basin. Based on genetic status (nonnative genetic admixture ≤ 10%), 36 Westslope Cutthroat Trout populations occupying 821 km of stream and 5,482 ha of lakes were identified as “conservation populations.” Most of the conservation populations (<i>N</i> = 27; 736 km of stream habitat) occurred in the Columbia River basin, whereas only a few geographically restricted populations were found in the South Saskatchewan River (<i>N</i> = 7; 55 km) and Missouri River (<i>N</i> = 2; 30 km) basins. Westslope Cutthroat Trout appear to be at imminent risk of genomic extinction in the South Saskatchewan and Missouri River basins, whereas populations in the Columbia River basin are widely distributed and conservation efforts are actively addressing threats from hybridization and other stressors. A diverse set of pro-active management approaches will be required to conserve, protect, and restore Westslope Cutthroat Trout populations in Glacier National Park throughout the 21st century.</p> <p>Received September 10, 2015; accepted March 30, 2016 Published online August 12, 2016</p

Effects of Hybridization between Nonnative Rainbow Trout and Native Westslope Cutthroat Trout on Fitness-Related Traits

<p>Hybridization between introduced and native fauna is a risk to native species and may threaten the long-term persistence of numerous taxa. Rainbow Trout <i>Oncorhynchus mykiss</i> has been one of the most widely introduced species around the globe and often hybridizes with native Cutthroat Trout <i>O. clarkii</i> in the Rocky Mountains. Previous work has shown that hybridization negatively affects reproductive success, but identification of the traits contributing to that reduction has been elusive. In this study, we used a combination of field and laboratory techniques to assess how hybridization with Rainbow Trout affects seven traits during several stages of Westslope Cutthroat Trout development: embryonic survival, ova size, ova energy concentration, sperm motility, juvenile weight, juvenile survival, and burst swimming endurance. Rainbow Trout admixture was correlated with an increase in embryonic survival and ova energy concentration but with a decrease in juvenile weight and burst swimming endurance. These correlations differed from previously observed patterns of reproductive success and likely do not explain the declines in reproductive success associated with admixture. Future investigation of additional, unstudied traits and the use of different environments may shed light on the traits responsible for reproductive success in admixed Cutthroat Trout.</p> <p>Received January 18, 2015; accepted June 16, 2015</p

Dryad Accession for Hotaling et al. 2017, Journal of Biogeography

Relevant files for the associated study: input files for PLINK and Fastsimcoal2, a key of individuals/populations, and raw SNP catalog as output by STACKS with a whitelist for the loci/SNPs used in this study