Molecular data elucidate cryptic diversity within the widespread Threadfin Shad (Dorosoma petenense: Clupeidae) across the Nearctic and Northern Neotropics

Intraspecific morphological variation in shads, Dorosoma anale and D. petenense (Actinopterygii: Clupeiformes: Clupeidae), in the Mexican Grijalva and Usumacinta river basins

“…Two of these lineages converge in the Grijalva-Usumacinta basins. The lineage with the broadest distribution inhabits the region from the Río Grande to the lower Grijalva and Usumacinta rivers in Mexico and Guatemala, while the other is restricted to the upper Usumacinta River and Petén Itzá Lake in Guatemala (Elías et al 2021). Curiously, in other Dorosoma species with similar distribution patterns, no significant genetic differences have been found (Elías et al 2021).…”

“…The highly diverse ichthyofauna of northern Middle America has a complex biogeographic history. Frequent geological, volcanic, and climatic events from the Late Cretaceous to the Miocene and Pleistocene determined the diversification and distribution of fishes in the region (Elías et al 2021). Biogeographic patterns and a large amount of endemism among freshwater species represent the clearest evidence of the hydrological history of northern Middle America (Albert et al 2020;Elías et al 2021).…”

“…This hydrological system is characterized by its diversity of fish species and large amount of endemism, which is predominantly observed in the Cichlidae and Poeciliidae families (Gómez-González et al 2015;Velázquez-Velázquez et al 2016;Soria-Barreto et al 2018;Sánchez et al 2019;Álvarez-Pliego et al 2021). Constant events involving vicariance resulting from the capture of rivers and changes in sea level favored the diversification of several lineages through geographic isolation (Albert et al 2020;Elías et al 2021). The construction of dams on the Grijalva River can be considered an example to test the recent effects of hydrological and environmental changes on the dynamics of fish populations, particularly the consequences of a reduction or interruption in genetic flow for morphological and functional differentiation (Sánchez et al 2019).…”

“…Nevertheless, the structure of the community in the upper regions of these rivers notably differs (Gómez-González et al 2015;Velázquez-Velázquez et al 2016;Soria-Barreto et al 2018). Studies of systematic, biogeography and population genetics have revealed that the upper regions of the two basins have independent evolutionary histories (Elías et al 2021;Beltrán-López et al 2021;Terán-Martínez et al 2021). The presence of relic endemic species such as the catfish of Chiapas (Lacantunia enigmatica Rodiles-Hernández, Hendrickson et Lundberg, 2005) and the livebearer (Xenodexia ctenolepis Hubbs, 1950) of the upper Usumacinta are evidence of the region's unique biogeographic history (Rodiles-Hernández et al 2005;Hrbek et al 2007;Elías et al 2021).…”

“…Although cichlids and poeciliids are the most diverse and abundant fish families within the Grijalva-Usumacinta system, other families also reflect the effects of the region's historic events. Such is the case of the genus Dorosoma, for which genetic evidence shows that cryptic diversity exists throughout the distribution of the species Dorosoma petenense (Günther, 1867) in Middle America, which consists of several lineages (Elías et al 2021). Two of these lineages converge in the Grijalva-Usumacinta basins.…”