Fonseca Fernando S, Domingues Rodrigo R, Hallerman Eric M, Hilsdorf Alexandre W S
Laboratório de Genética de Organismos Aquáticos e Aquicultura, Unidade de Biotecnologia, Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes, Mogi das Cruzes, Brazil.
Instituto de Pesca, Agência Paulista de Tecnologia dos Agronegócios, Secretaria de Agricultura e Abastecimento do Estado de São Paulo, São José do Rio Preto, Brazil.
Front Genet. 2017 Dec 12;8:196. doi: 10.3389/fgene.2017.00196. eCollection 2017.
The long-whiskered catfish (Family Pimelodidae) is endemic to the Paraíba do Sul River basin in southeastern Brazil. This species was heavily exploited by artisanal fisheries and faces challenges posed by dams, introduced species, and deterioration of critical habitat. The remaining populations are small and extirpated from some locales, and the species is listed as critically endangered in Brazil. Screening variation at a partial mitochondrial control region sequence (mtCR) and 20 microsatellite loci, we: (i) describe the patterns of genetic diversity along its current distributional range; (ii) test the null hypothesis of panmixia; (iii) investigate the main factors driving its current population structure, and (iv) propose management of broodstock for fostering recovery of wild populations through genetically cognizant restocking. Our microsatellite data for 70 individuals from five collections indicate moderate levels of heterozygosity ( = 0.45) and low levels of inbreeding ( = 0.016). Individual-based cluster analyses showed clear genetic structure, with three clusters of individuals over the collection area with no mis-assigned individuals, suggesting no recent migration among the three clusters. Pairwise values showed moderate and significant genetic differentiation among all populations so identified. The MUR population may have suffered a recent demographic reduction. mtCRs for 70 individuals exhibited 36 haplotypes resulting from 38 polymorphic sites. Overall, mitochondrial haplotype diversity was 0.930 (±0.023) and nucleotide diversity was 0.011 (±0.002). Significant population structure was observed, with ϕ = 0.226. Genetic markers could be used in a hatchery-based restoration program emphasizing breeding of pairs with low kinship values in order to promote retention of genetic diversity and avoid inbreeding. Individual average kinship relationships showed 87.3% advised matings, 11.0% marginal matings, and 1.7% advised against. While these results comprise a contribution toward planning better breeding management and monitoring, parallel actions to be undertaken include surveying healthy riverine habits for reintroduction and continued searching for wild individuals to introduce new variation into the captive broodstock to avoid adaptation to captivity and to minimize inbreeding.
长须鲶鱼（油鲶科）原产于巴西东南部的帕拉伊巴河盆地。该物种曾遭受个体渔业的过度捕捞，如今面临着水坝、外来物种以及关键栖息地退化带来的挑战。现存种群规模较小，部分区域已灭绝，在巴西被列为极度濒危物种。通过筛选部分线粒体控制区序列（mtCR）和20个微卫星位点的变异情况，我们：（i）描述了其当前分布范围内的遗传多样性模式；（ii）检验了随机交配的零假设；（iii）调查了驱动其当前种群结构的主要因素；（iv）提出了亲鱼管理方案，以通过有基因意识的放流促进野生种群的恢复。我们对来自五个采集点的70个个体的微卫星数据显示，杂合度处于中等水平（ = 0.45），近亲繁殖水平较低（ = 0.016）。基于个体的聚类分析显示出明显的遗传结构，在采集区域内有三个个体聚类，没有个体被错误归类，这表明这三个聚类之间近期没有迁移。成对 值显示所有已识别种群之间存在中等程度且显著的遗传分化。MUR种群可能近期经历了种群数量减少。70个个体的mtCR显示出38个多态性位点产生的36种单倍型。总体而言，线粒体单倍型多样性为0.930（±0.023），核苷酸多样性为0.011（±0.002）。观察到显著的种群结构，ϕ = 0.226。遗传标记可用于基于孵化场的恢复计划，该计划强调培育亲缘关系值低的配对，以促进遗传多样性的保留并避免近亲繁殖。个体平均亲缘关系显示，87.3%的交配建议可行，11.0%的交配处于边缘状态，1.7%的交配不建议进行。虽然这些结果有助于更好地规划繁殖管理和监测，但同时要采取的并行行动包括调查健康的河流栖息地以便重新引入，并持续寻找野生个体，将新的变异引入圈养亲鱼中，以避免适应圈养环境并尽量减少近亲繁殖。
