Janzen Francesco H, Pérez-Rodríguez Rodolfo, Domínguez-Domínguez Omar, Hendrickson Dean A, Sabaj Mark H, Blouin-Demers Gabriel
Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán 580004, Mexico.
Mol Phylogenet Evol. 2023 May;182:107746. doi: 10.1016/j.ympev.2023.107746. Epub 2023 Feb 26.
Insular habitats have played an important role in developing evolutionary theory, including natural selection and island biogeography. Caves are insular habitats that place extreme selective pressures on organisms due to the absence of light and food scarcity. Therefore, cave organisms present an excellent opportunity for studying colonization and speciation in response to the unique abiotic conditions that require extreme adaptations. One vertebrate family, the North American catfishes (Ictaluridae), includes four troglobitic species that inhabit the karst region bordering the western Gulf of Mexico. The phylogenetic relationships of these species have been contentious, and conflicting hypotheses have been proposed to explain their origins. The purpose of our study was to construct a time-calibrated phylogeny of Ictaluridae using first-occurrence fossil data and the largest molecular dataset on the group to date. We test the hypothesis that troglobitic ictalurids have evolved in parallel, thus resulting from repeated cave colonization events. We found that Prietella lundbergi is sister to surface-dwelling Ictalurus and that Prietella phreatophila + Trogloglanis pattersoni are sister to surface-dwelling Ameiurus, suggesting that ictalurids colonized subterranean habitats at least twice in evolutionary history. The sister relationship between Prietella phreatophila and Trogloglanis pattersoni may indicate that these two species diverged from a common ancestor following a subterranean dispersal event between Texas and Coahuila aquifers. We recovered Prietella as a polyphyletic genus and recommend P. lundbergi be removed from this genus. With respect to Ameiurus, we found evidence for a potentially undescribed species sister to A. platycephalus, which warrants further investigation of Atlantic and Gulf slope Ameiurus species. In Ictalurus, we identified shallow divergence between I. dugesii and I. ochoterenai, I. australis and I. mexicanus, and I. furcatus and I. meridionalis, indicating a need to reexamine the validity of each species. Lastly, we propose minor revisions to the intrageneric classification of Noturus including the restriction of subgenus Schilbeodes to N. gyrinus (type species), N. lachneri, N. leptacanthus, and N. nocturnus.
岛屿栖息地在进化理论的发展中发挥了重要作用，包括自然选择和岛屿生物地理学。洞穴是岛屿栖息地，由于缺乏光照和食物稀缺，对生物施加了极端的选择压力。因此，洞穴生物为研究生物如何响应需要极端适应的独特非生物条件而进行的定殖和物种形成提供了绝佳机会。有一个脊椎动物家族，即北美鲶鱼科（Ictaluridae），其中包括四种穴居物种，它们栖息在墨西哥湾西部边缘的岩溶地区。这些物种的系统发育关系一直存在争议，并且已经提出了相互矛盾的假设来解释它们的起源。我们研究的目的是利用首次出现的化石数据和该类群迄今为止最大的分子数据集构建鲶鱼科的时间校准系统发育树。我们检验了穴居鲶鱼科物种平行进化的假设，即它们是由多次洞穴定殖事件导致的。我们发现伦氏普列特鲶（Prietella lundbergi）是栖息于地表的真鮰属（Ictalurus）的姐妹群，而穴栖普列特鲶（Prietella phreatophila）+ 帕氏盲鲶（Trogloglanis pattersoni）是栖息于地表的叉尾鮰属（Ameiurus）的姐妹群，这表明鲶鱼科在进化历史上至少两次定殖到地下栖息地。穴栖普列特鲶和帕氏盲鲶之间的姐妹关系可能表明这两个物种在德克萨斯州和科阿韦拉含水层之间的一次地下扩散事件后从一个共同祖先分化而来。我们发现普列特鲶属是一个并系属，并建议将伦氏普列特鲶从该属中移除。关于叉尾鮰属，我们发现了一种可能未被描述的物种，它是扁头叉尾鮰（A. platycephalus）的姐妹群，这值得对大西洋和墨西哥湾沿岸的叉尾鮰属物种进行进一步研究。在真鮰属中，我们确定了杜氏真鮰（I. dugesii）和奥氏真鮰（I. ochoterenai）、南方真鮰（I. australis）和墨西哥真鮰（I. mexicanus）以及叉尾真鮰（I. furcatus）和南方真鮰之间的分化较浅，这表明需要重新审视每个物种的有效性。最后，我们对异囊鲶属（Noturus）的属内分类提出了一些小的修订，包括将 Schilbeodes 亚属限制为环纹异囊鲶（N. gyrinus，模式种）、拉克纳异囊鲶（N. lachneri）、细棘异囊鲶（N. leptacanthus）和夜异囊鲶（N. nocturnus）。
