Phylogenetic analyses of the subgenus Mollienesia (Poecilia, Poeciliidae, Teleostei) reveal taxonomic inconsistencies, cryptic biodiversity, and spatio-temporal aspects of diversification in Middle America

Abstract

The subgenus Mollienesia is a diverse group of freshwater fishes, including species that have served as important models across multiple biological disciplines. Nonetheless, the taxonomic history of this group has been conflictive and convoluted, in part because the evolutionary relationships have not been rigorously resolved. We conducted a comprehensive molecular phylogenetic analysis of the subgenus Mollienesia to identify taxonomic discrepancies and potentially identify undescribed species, estimate ancestral areas of origin and estimate dates of divergence, as well as explore biogeographical patterns. Our findings confirm the presence of three main clades composed of the P. latipinna, P. sphenops, and P. mexicana species complexes. Unlike previously hypothesized morphology-based analyses, species found on the Caribbean Islands are not part of Mollienesia, but are more closely related to species of the subgenus Limia. Our study also revealed several taxonomic inconsistencies and distinct lineages in the P. mexicana species complex that may represent undescribed species. The diversity in the subgenus Mollienesia is a result of dynamic geologic activity leading to vicariant events, dispersal across geologic blocks, and ecological speciation.

The origin and biogeographic diversification of fishes in the family Poeciliidae

“…Our analyses confirmed Palacios et al’s [25] finding of an explicit link between South America and the Caribbean for the Poecilia subgenus Limia . Prior investigators had inferred that Limia was derived from South America [12, 24] but their analyses did not include Limia heterandria .…”

“…While arguments have been made for vicariance as a cause of the nodes between 14 and 25, at least some of those that lie between nodes 1 and 13 must represent dispersal through brackish water or marine barriers, made possible by the ability of many species of Gambusia to tolerate high salt concentrations. Palacios et al [25] arrived at the same conclusion for the subgenus Mollienesia (Node 21) and the same could be true for Limia (Node 19). Species in both taxa can be found in brackish water and hence are tolerant of high salt concentrations [10, 93].…”

“…This inclusion reveals a monophyletic cluster of species that spans the distance between the presumed origin of the common ancestor of the genus and the Caribbean radiation. Palacios et al [25] also show that a triad of Caribbean species ( Poecilia dominicensis , P . hispaniolae , P .…”

“…This integration has been applied to individual genera, subgenera or species (e.g. Brachyraphis [15]- Gambusia –[16, 17]; Poeciliopsis —[18, 19]; Girardinu s—[20]; Pseudoxiphophorus –[21]; Poecilia –[22, 23]; Limia –[24]; Mollienesia –[25]). Hrbek et al [12] presented the most recent comprehensive family-wide analysis.…”

Checklist of the continental fishes of the state of Chiapas, Mexico, and their distribution

“…Records of the Mexican tetra in Chiapas probably contain misidentifications as mentioned by Lozano-Vilano and Contreras-Balderas (1987) and Ornelas-García et al (2008), thus supporting the absence of this species in Southern Mexico. We have included Important and recent taxonomic changes made in the family Cichlidae by McMahan et al (2015) and Říčan et al (2016), the family Poeciliidae by Palacios et al (2016) and the family Profundulidae by Morcillo et al (2016).…”