Cunha Marina S, Fregonezi Aline R, Fava Lucioni, Hilsdorf Alexandre W S, Campos Lucio A O, Dergam Jorge A
1 Departamento de Biologia Animal, Universidade Federal de Viçosa, Viçosa, Brazil.
2 Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Brazil.
Zebrafish. 2019 Feb;16(1):115-127. doi: 10.1089/zeb.2018.1668. Epub 2018 Nov 20.
Astyanax bimaculatus, a ubiquitous species in many Neotropical basins, is characterized by a complex taxonomy and are currently considered a species complex. The goal of this study was to analyze 31 populations (N = 136) of this species from southeastern Brazil using cytogenetic techniques: conventional staining, nucleolar organizer region (Ag-NOR), C-banding, and 18S and 5S recombinant DNA fluorescent in situ hybridization (FISH) probes; and molecular techniques: S72, RAG2, and COI. All populations were 2n = 50 (6m + 20sm +18st +6a); Ag-NORs were predominantly simple, C-banding revealed high variation levels within and among basins, and the FISH probes 18S and 5S were restricted to chromosome pairs 14 and 7, respectively. The S72 was uninformative for phylogenetic analyses, and RAG2 showed no variation among populations. The COI gene revealed three haplogroups. The most basal was composed of Pandeiros population (São Francisco Basin) that diverged in the Middle Miocene. The second was composed of A. altiparanae from the Upper Paraná Basin and Espírito Santo Stream (Paraíba do Sul Basin), whereas the third was composed of Astyanax lacustris from São Francisco and coastal basins. The second and third haplogroups diverged in the Pleistocene, indicating that diversification of the bimaculatus complex was driven by tectonic activity and sea-level fluctuations.
双线丽脂鲤（Astyanax bimaculatus）是许多新热带盆地中常见的物种，其分类复杂，目前被认为是一个复合物种。本研究的目的是使用细胞遗传学技术分析来自巴西东南部的该物种的31个种群（N = 136）：常规染色、核仁组织区（Ag-NOR）、C带以及18S和5S重组DNA荧光原位杂交（FISH）探针；以及分子技术：S72、RAG2和COI。所有种群的染色体数目均为2n = 50（6m + 20sm + 18st + 6a）；Ag-NORs主要为简单型，C带显示流域内和流域间存在高度变异，FISH探针18S和5S分别局限于第14和第7号染色体对。S72对系统发育分析无信息价值，RAG2在种群间无变异。COI基因揭示了三个单倍群。最基部的单倍群由潘代罗斯种群（圣弗朗西斯科盆地）组成，该种群在中新世中期分化。第二个单倍群由来自巴拉那河上游盆地和圣埃斯皮里图河（南帕拉伊巴盆地）的高巴拉那双线丽脂鲤组成，而第三个单倍群由来自圣弗朗西斯科和沿海盆地的湖栖双线丽脂鲤组成。第二和第三个单倍群在更新世分化，表明双线丽脂鲤复合物种的多样化是由构造活动和海平面波动驱动的。
