A significant portion of the threatened ichthyofauna is composed by annual fish, whose gene flow is commonly affected by large water bodies. Austrolebias minuano is an endangered species that lives in temporary wetlands of the Patos-Mirim Lagoon System, in Brazil, inhabiting both margins of the Patos Lagoon. This species has previously been target of taxonomic split, leading to the description of A. pongondo, and there are doubts about its distinction in relation to A. charrua. The objective of this study is to understand the evolutionary patterns and processes associated with the geographic distribution of A. minuano, A. charrua and A. pongondo, while assessing their taxonomic status. For this, specimens were collected along the distribution range of the three species, and sequences of the mitochondrial cyt b and CO1 and of the nuclear ENC1 gene were characterized. Phylogenetic and phylogeographic approaches showed subdivision of the dataset in four lineages: one clustering the type population of A. minuano with A. charrua, two presenting populations previously assigned to A. minuano that inhabit the Eastern margin of the Patos Lagoon and one corresponding to A. pongondo. Patterns of migration and genetic divergences support the assignment of each of these lineages as independent evolutionary units. In the chronophylogenetic reconstructions, the two lineages inhabiting the Western margin of the Patos Lagoon constituted the first to branch out whereas the eastern lineages diverged more recently. These divergences seem to have occurred before the Pleistocene Lagoon-Barrier Depositional System related to the paleogeographic evolution of the South American Coastal Plain.

中文翻译：

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新热带一年生鱼 Austrolebias minuano、Austrolebias charrua 和 Austrolebias pongondo（Cyprinodontiformes：Rivulidae）的系统地理学分析和分类不一致

受威胁鱼群的很大一部分由一年生鱼类组成，其基因流通常受到大型水体的影响。Austrolebias minuano 是一种濒临灭绝的物种，生活在巴西帕托斯-米里姆泻湖系统的临时湿地，栖息在帕托斯泻湖的两侧。该物种以前一直是分类学分裂的目标，导致对 A. pongondo 的描述，并且对其与 A. charrua 的区别存在怀疑。本研究的目的是了解与 A. minuano、A. charrua 和 A. pongondo 地理分布相关的进化模式和过程，同时评估它们的分类地位。为此，沿三个物种的分布范围收集了标本，并表征了线粒体细胞色素 b 和 CO1 以及核 ENC1 基因的序列。系统发育和系统地理学方法显示数据集细分为四个谱系：一个将 A. minuano 的类型种群与 A. charrua 聚类，两个现有种群以前分配给居住在 Patos Lagoon 东部边缘的 A. minuano，一个对应于 A. . pongondo。迁移模式和遗传差异支持将这些谱系中的每一个指定为独立的进化单元。在时间系统发育重建中，居住在帕托斯泻湖西部边缘的两个谱系是第一个分支的，而东部谱系最近发生了分歧。