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a MrBayes inferred phylogram for 56 Noturus taylori mitochondrial cytochrome b sequences. The posterior probabilities are presented at each node. Bolded posterior probabilities imply significance at α = 0.05. Numbers in parentheses correspond to haplotype numbers in the haplotype network. The scale bar represents substitutions per site. b Mitochondrial DNA haplotype network generated by statistical parsimony analysis in TCS. Circles (haplotypes) are proportional to the sampled individuals with the respective haplotypes, lines represent one mutational step between haplotypes, and black circles on lines represent an additional mutational step
Source publication
The Caddo Madtom, Noturus taylori, is endemic to three river drainages of the Ouachita Highlands in the southeastern United States. Conservation concern for N. taylori has been heightened by recent studies based on analyses of allozyme data suggesting population decline and a possible extirpation event, which lead to N. taylori petitioned for listi...
Citations
... Genetic studies of N. taylori (Turner and Robison 2006, allozymes;McCall and Fluker 2020, mtDNA and microsatellites) found that divergence between Caddo and upper Ouachita river populations has a historical basis, and was established prior to the closure of Blakely Mountain (1953) and DeGray (1969) dams along the Ouachita and Caddo rivers, respectively. While Caddo and upper Ouachita populations show no evidence of recent declines in genetic diversity, withindrainage divergence and low estimated migration rates suggest somewhat limited dispersal capabilities and reservoir-induced population fragmentation in one tributary of the upper the Ouachita River drainage (Turner and Robison 2006, McCall and Fluker 2020, Robison and Buchanan 2020. ...
The Caddo Madtom, Noturus taylori, is a small catfish endemic to the Ouachita Mountain ecoregion in
Arkansas, with habitat altered by land use practices and reservoir dams. We examined aspects of
distribution, abundance, habitat, and life history of N. taylori during seasonal sampling from winter 2016
through fall 2017. Our sampling data were concordant with previous studies that suggested N. taylori is
more widespread and has higher catch per unit effort in the Caddo River drainage when compared to the
upper Ouachita River drainage. We did not detect N. taylori in the Little Missouri River drainage, where it is
presumed extirpated. A total of 370 individuals ranging from 14–76 mm (mean = 45.1 mm) standard
length (SL) were collected during seasonal samples. Length-frequency analyses estimated a maximum
age of 3 years for N. taylori, and we identified three discernable age classes with the emergence of youngof-year (age 0 cohort) in summer: age 0 (up to ~40 mm SL); age 1 (~41-60 mm SL); and age 2+ (>60 mm
SL). Sites where N. taylori was captured had an average depth of 20.6 cm, an average base velocity of
0.18 m/sec, and were dominated primarily by a mix of gravel, pebble, and cobble. Despite the relatively
higher abundances of N. taylori in the Caddo River, we recommend that long-term, periodic monitoring of
N. taylori would be an important conservation tool to assess potential future changes in distribution,
habitat, occurrence, and abundance. Future studies that implement occupancy and habitat suitability
modeling are needed to better understand suitable and preferred habitat of N. taylori.
... We estimated the recent gene flow between the clusters in agreement with Geneland with the software BayesAss 1.3 (Wilson & Rannala, 2003), based on MCMC resampling to estimate recent migration rate (m), and based on the proportion of individuals within each locality, which are assigned with a high probability to other populations, allowing the detection of migration events which occurred a few generations ago. BayesAss considers deviation from Hardy-Weinberg equilibrium but assumes linkage equilibrium (McCall & Fluker, 2020) and a negligible effect of recent genetic drift or migration in the population allelic frequencies (Madlen et al., 2020). We ran BayesAss with 10 million iterations, a sampling frequency of 2,000 and a burn-in of 10%. ...
Habitat loss and fragmentation are among the greatest threats to biodiversity since unsuitable habitat can be a significant barrier to gene flow, disrupting the connectivity of populations. In this scenario, landscape genetic approaches have been applied as invaluable tools to demonstrate how contemporary habitat alterations affect gene flow. In this study, we used nine microsatellite genotypes to determine the landscape features driving genetic diversity, structure, and functional connectivity among eleven sampling sites of a micro‐endemic, and critically endangered salamander ( Pseudoeurycea robertsi ) in the Nevado de Toluca Volcano. We also modelled the ecological niche of P . robertsi to assess the most important habitat features associated with its probability of presence and analyzed the corridor network to identify important core areas and corridors to keep the network connected, as well as points where the network connection is lost or tightened. Moreover, we performed a redundancy analysis to assess the effect of genetic distance and habitat resistances on gene flow. We found the highest levels of genetic diversity and connectivity at the northwestern part of the Volcano. Meson Viejo sampling site was of especial importance to overall network connectivity. We found low levels of migration rates and low levels of genetic structure. The most important habitat feature associated with probability of presence of Pseudoeurycea robertsi was the Abies forest, and two models were significant under the RDA analysis: Abies forest and Abies forest+Grasslands. We recommend prioritizing the areas of the northwestern and central parts of the volcano in conservation programs.
Abstract in Spanish is available with online material.
The Third International Catfish Symposium was held in Little Rock, Arkansas, in 2020 and provided another milestone to gauge advances in knowledge related to conservation and management of these valuable fishes. Attendees from 29 states and 4 countries gathered to communicate research and information on the conservation, ecology, and management of the world’s catfishes. During 3 d of technical sessions and workshops, 74 oral presentations and 17 posters were shared with 198 attending fisheries professionals. Plenary and oral presentations were recorded and are available online (https://www.youtube.com/channel/UCHNt7ZV05DLWoe4qJO798Pw/videos), aligning with the symposium theme of “Communicating Catfish Science.” Technical sessions explored current research and management issues that included population demographics, introduced catfish populations, sampling methods, harvest management, human dimensions, conservation, habitat use and movement, biology, and aging methods. Ultimately, 38 manuscripts were peer reviewed and published as this special issue of the North American Journal of Fisheries Management. Interest in catfish science, as gauged by publications in six peer‐reviewed fisheries journals, has grown steadily since a 1910 catfish aquaculture article appeared in the Transactions of the American Fisheries Society. Biology and ecology topics became prominent in the 1970s and 1980s, while articles on techniques and fisheries management have grown steadily through 2020. Ecology, fisheries management, and techniques were the most published topics in the three international catfish symposia. Future research and management efforts will continue similar work but also seek to address the expanding role of catfish as invasive species and a better understanding of the ecology and conservation of small‐bodied native catfish. Among the greatest challenges will be adapting current tools and identifying future knowledge gaps as we experience a changing climate. This will require an enhanced understanding of transforming ecosystems and advanced adaptive management applications. The decadal occurrence of a dedicated symposium has served to summarize progress and focus future efforts to advance catfish science.
