Data from: Time-series analysis reveals genetic responses to intensive management of razorback sucker (Xyrauchen texanus)

Time-series analysis is used widely in ecology to study complex phenomena, and may have considerable potential to clarify relationships of genetic and demographic processes in natural and exploited populations. We explored the utility of this approach to evaluate population responses to management in razorback sucker, a long-lived and fecund, but declining freshwater fish species. A core population in Lake Mohave (Arizona-Nevada, USA) has experienced no natural recruitment for decades, and is maintained by harvesting naturally produced larvae from the lake, rearing them in protective custody, and repatriating them at sizes less vulnerable to predation. Analyses of mtDNA and 15 microsatellites characterized for sequential larval cohorts collected over a 15-year time series revealed no changes in geographic structuring, but indicated significant increase in mtDNA diversity for the entire population over time. Likewise, ratios of annual effective breeders to annual census size (Nb/Na) increased significantly despite seven-fold reduction of Na. These results indicated that conservation actions diminished near-term extinction risk due to genetic factors, and should now focus on increasing numbers of fish in Lake Mohave to ameliorate longer-term risks. More generally, time series analysis permitted robust testing of trends in genetic diversity, despite low precision of some metrics

Use of Molecular Techniques to Confirm Nonnative Fish Predation on Razorback Sucker Larvae in Lake Mohave, Arizona and Nevada

<p>Larval predation by nonnative fishes has long been implicated in the decline of western native large-river fishes, but visual assessment of predation is difficult due to the postconsumption degradation of fragile larvae. Molecular techniques were used to demonstrate predation on the larvae of endangered Razorback Suckers <i>Xyrauchen texanus</i> by nonnative juvenile centrarchids in field samples from Lake Mohave, Arizona–Nevada, where larvae are seasonally abundant. Razorback Sucker DNA was detected in the gut contents of 7% and 9% of Bluegills <i>Lepomis macrochirus</i> and in 14% and 15% of Green Sunfish <i>L. cyanellus</i> that were captured during spring 2014 and 2015, respectively. There was no significant (α = 0.05) effect of predator TL, predator species, or year on the presence of larval DNA. Juvenile centrarchids have the potential to consume substantial numbers of Razorback Sucker larvae and thus to impact recruitment. The control of nonnative fishes may be impractical, but a viable alternative for mitigation of their impacts is to provide nonnative-free refugia for native large-river fishes.</p> <p>Received June 17, 2016; accepted September 19, 2016 Published online January 19, 2017</p

Data from: Retention of ancestral genetic variation across life-stages of an endangered, long-lived iteroparous fish

As with many endangered, long-lived iteroparous fishes, survival of razorback sucker depends on a management strategy that circumvents recruitment failure that results from predation by non-native fishes. In Lake Mohave, AZ-NV, management of razorback sucker centers on capture of larvae spawned in the lake, rearing them in off-channel habitats, and subsequent release ('repatriation') to the lake when adults are sufficiently large to resist predation. The effects of this strategy on genetic diversity, however, remained uncertain. After correction for differences in sample size among groups, metrics of mtDNA (number of haplotypes, NH, and haplotype diversity, HD) and microsatellite (number of alleles, NA, and expected heterozygosity, HE) diversity did not differ significantly between annual samples of repatriated adults and larval year-classes or among pooled samples of repatriated adults, larvae, and wild fish. These findings indicate that the current management program thus far maintained historical genetic variation of razorback sucker in the lake. Because effective population size, Ne, is closely tied to the small census population size (Nc = ~1,500-3,000) of razorback sucker in Lake Mohave, this population will remain at risk from genetic as well as demographic risk of extinction unless Nc is increased substantially

Individual mtDNA haplotypes

For each individual, the first column provides field id number (including location and date), second column provides lab id (sorted by year), and the third column identifies the haplotype

mtDNA haplotype sequences

DNA sequences of each of the haplotypes identified in this study. This file, in conjunction with the haplotypes, can be used to estimate population genetic parameters

Individual microsatellite genotypes

The first line provides the header, sample ID and locus name. Each locus is named twice, once for each allele. The following lines provides the genotypes for each individual

DataSheet_1_Increasing availability of reference mitochondrial genomes for imperiled fishes in western North America for environmental DNA assay design and species monitoring.docx

The full text of this article can be freely accessed on the publisher's website

RBS_mtDNA

This is an Arlequin file that contains counts of each mtDNA haplotype (311 bp cytb) in each collection, including annual samples from 1997-2010 for repatriated adults, larval cohorts, and wild fish (pooled)

RBS_Haps

This file contains DNA sequences for 34 mitochondrial DNA haplotypes (311 bp fragment of cytochome b)

Carson et al 2016 RBS msat data

This file contains genotypic data 13 microsatellite loci for all individuals, including annual collections of repatriated adults (1997-2010), larval year classes (1997-2010), and the pooled sample of wild fish (1997-2010)