Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Laboratory of Vertebrate Systematics, Porto Alegre, State of Rio Grande do Sul, Brazil.
PLoS One. 2020 Sep 3;15(9):e0237160. doi: 10.1371/journal.pone.0237160. eCollection 2020.
Pareiorhaphis hystrix is a widely distributed species, occurring in the upper and middle Uruguay River and in the Taquari River basin, Patos Lagoon system, southern Brazil. Morphological variation has been detected throughout the distribution of P. hystrix, and this work seeks to test the conspecific nature of populations in several occurrence areas. Specimens from six areas in the Uruguay River basin and three in the Taquari River basin were compared. Variance analysis (ANOVA) was performed for the meristic data, and Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were conducted for morphometric data. Molecular analyses used coI, cytb, 12S and 16S mitochondrial genes, examining nucleotide diversity, haplotype diversity, genetic distance, and delimitation of possible multiple species through the Generalized Mixed Yule Coalescent (GMYC) method. Phylogenetic relationships of studied populations were also investigated through Bayesian inference. While PCA indicated a tendency of overlap between areas, ANOVA and LDA detected a subtle differentiation between populations from the two hydrographic basins. Yet, both latter analyses recovered the population from Pelotas River, a tributary to Uruguay River, as more similar to populations from Taquari River, which is congruent to morphological observations of anterior abdominal plates. The molecular data indicated a nucleotide diversity lower than the haplotypic diversity, suggestive of recent expansion. The concatenated haplotype network points to slight differentiation between areas, with each locality presenting unique and non-shared haplotypes, although with few mutational steps in general. The species delimitation by coalescence analysis suggested the presence of a variable number of OTUs depending on the inclusion or exclusion of an outgroup. In general, the morphological data suggest a subtle variation by river basin, while the genetic data indicates a weak population structuration by hydrographic areas, especially the Chapecó and Passo Fundo rivers. However, there is still not enough differentiation between the specimens to suggest multiple species. The iterative analyses indicate that Pareiorhaphis hystrix is composed of a single, although variable, species.
黑眶蟾鱼分布广泛，存在于乌拉圭河的上游和中游以及塔夸里河流域、帕托斯泻湖系统和巴西南部。在黑眶蟾鱼的整个分布范围内都检测到了形态变异，本研究旨在测试多个分布区域种群的同物异性。对来自乌拉圭河流域的六个地区和塔夸里河流域的三个地区的标本进行了比较。对可数数据进行方差分析（ANOVA），对形态数据进行主成分分析（PCA）和线性判别分析（LDA）。分子分析使用线粒体基因 coI、cytb、12S 和 16S，检查核苷酸多样性、单倍型多样性、遗传距离，并通过广义混合 Yule 合并（GMYC）方法对可能的多个物种进行划分。还通过贝叶斯推断研究了种群的系统发育关系。虽然 PCA 表明各地区之间存在重叠趋势，但 ANOVA 和 LDA 检测到两个水系种群之间存在微妙分化。然而，后两种分析都发现来自乌拉圭河支流佩洛塔斯河的种群与塔夸里河的种群更为相似，这与前腹板的形态观察结果一致。分子数据表明核苷酸多样性低于单倍型多样性，提示近期扩张。连锁单倍型网络表明各地区之间存在轻微分化，每个地点都有独特且不共享的单倍型，但总体上突变步骤较少。合并分析的物种划分表明，根据是否包含外群，存在可变数量的 OTU。总体而言，形态数据表明流域之间存在微妙的变异，而遗传数据表明流域之间的种群结构较弱，特别是沙佩科和帕索丰杜河。然而，标本之间的分化程度还不足以表明存在多个物种。迭代分析表明，黑眶蟾鱼由一个单一的物种组成，尽管存在变异。
