Genetic differentiation in the genus Characodon: implications for conservation and taxonomy

Abstract

The subfamily Goodeinae is a group of fishes endemic to the Mexican highlands. Most of the species are restricted to small and isolated streams or springs. Within this subfamily, the genus Characodon is the earliest diverging lineage of which three species have been described: C. lateralis, C. audax, and C. garmani, with the latter, considered extinct. Characodon lateralis and C. audax are classed as endangered, and have been the subject of taxonomic controversy since their description: previous studies have recognized a genetic differentiation in two groups separated by the El Salto waterfall, but morphological analyses contradict these genetic results. We perform a phylogeographic study using the mitochondrial cytb gene and d-loop region to elucidate the evolutionary history of C. lateralis and C. audax. The results with both markers show the presence of two highly differentiated haplogroups; one distributed north and the other distributed south of the waterfall, with genetic distances of 1.7 and 13.1% with cytb and d-loop respectively, and divergence calculated to have occurred 1.41 Mya. Significant genetic structure was found within each haplogroup and suggests the existence of at least four Evolutionary Significant Units (ESUs) within the examined populations. The possible processes identified as contributing to the formation of differentiated genetic groups are isolation, low population size, recurrent bottlenecks, and the strong sexual selection exhibited by the genus.

Multi-locus phylogeny of the catfish genus Ictalurus Rafinesque, 1820 (Actinopterygii, Siluriformes) and its systematic and evolutionary implications

“…Thus, the distribution of I. dugesii is confirmed for three disjunct river basins in central Mexico, i.e., the Lerma-Chapala system and the Ameca and Armeria Rivers. This is in accordance with other co-distributed fish species in the region, such as the catostomid Moxostoma austrinum Bean, 1880 [ 60 ], and several species of goodeids ( 61 – 62 ).…”

“…We also corroborated previously synonymized species such as I. ochoterenai, I. australis , and I. meridionalis . As in other taxonomically underestimated fish groups ( 35 , 62 , 65 , 78 – 79 ), there has been a lack of morphological studies and/or taxonomic revisions addressing these differentiation patterns in Ictaluridae, a conspicuous, economically important, popular, and important group of fishes. An integrative taxonomy approach is required to describe the evolutionary history of the group and to achieve a better understanding of its species composition and thereby improve its conservation.…”

Historical biogeography of New World Killifishes (Cyprinodontiformes: Funduloidea) recapitulates geographical history in the Gulf of México watershed

“…Loss of Goodeids from the Gulf of México drainage could reflect Late Miocene integration of the ancestral Río Nazas with the Río Grande, which facilitated an influx of fishes (Hoagstrom & Osborne, 2021). Characodon persisted only in remote basins († C. garmani , Mayran-Parras Basin; C. audax-C. lateralis , Río Tunal (Beltrán-López et al ., 2021), potentially protected from invading fishes. Positioning of Goodeinae on the TMVB throughout its tectonic evolution, which lasted 17 my (Ferrari et al ., 2012), the lineage experienced frequent drainage reorganizations and shifting hydrographic barriers (Barbour, 1973; Domínguez-Domínguez et al ., 2010; Pérez-Rodríguez et al ., 2015).…”

“…Positioning of Goodeinae on the TMVB throughout its tectonic evolution, which lasted 17 my (Ferrari et al, 2012), the lineage experienced frequent drainage reorganizations and shifting hydrographic barriers (Barbour, 1973;Domínguez-Domínguez et al, 2010;Pérez-Rodríguez et al, 2015). Stream capture was likely the main mode of range expansion and diversification (Webb et al, 2004;Domínguez-Domínguez et al, 2010;Beltrán-López et al, 2021).…”

Biotic regionalization of freshwater fishes in Northern Middle America highlights high beta diversity created by prominent biogeographic barriers

“…In particular, small Pacific-slope rivers south from Río Tehuantepec are generally depauperate, but include examples of fishes reaching the Balsas-Nacaome BR from Gulf of Mexico and Caribbean drainages of the Grijalva-Usumacinta BR (Bussing 1976, Miller et al 2005. The faunas of Ríos Armería and Balsas in the northern Balsas-Nacaome BR have received fishes of Nearctic origin via exchanges with the Río Lerma of the Sonora-Lerma BR within the Trans-Mexican Volcanic Belt (Miller et al 2005, Domínguez-Domínguez et al 2011, Beltrán-López et al 2021.…”