Influenced but not determined by historical events: genetic, demographic and morphological differentiation inHeleobia ascotanensisfrom the Chilean Altiplano

Abstract

In the present study, we focus on the phylogeographic pattern, demographic history and morphological differentiation of Heleobia ascotanensis, a freshwater gastropod restricted to the Ascotán saltpan in the Chilean Altiplano. The current distribution of the species is limited to twelve isolated or partially isolated springs that were affected by transitions between humid and arid periods during last glaciations. The genetic analysis of 322 specimens showed that H. ascotanensis is subdivided into three genetically divergent populations, with low and moderate degrees of historical gene flow among them and incipient morphological differentiation as a consequence of genetic and geographical isolation. Molecular analyses revealed different demographic histories among populations which seem to respond independently to climatic events, probably due to an environmental imposition and idiosyncratic strategies developed to cope with water availability. The results of this study and co-distributed taxa support the hypothesis that contemporary and historical events have influenced microevolutionary differentiation of these snails, although there is a need to complement further information to predict genetic or morphological divergence at microgeographic scale.

Coping With Dynamism: Phylogenetics and Phylogeographic Analyses Reveal Cryptic Diversity in Heleobia Snails of Atacama Saltpan, Chile

“…In this sense, multiple studies have shown that, in general, each species of the genus is restricted to a single hydrological system or basin (Kroll et al, 2012;Collado et al, , 2016a. In addition, the study revealed a genetic structure within the system congruent with the geographic separation of the sampled sites (latitudinal differentiation), a result similar to that reported in H. ascotanensis, a species that inhabits the Ascotán Saltpan located approximately 200 km north of the Atacama Saltpan (Valladares et al, 2018). The mitochondrial tree also showed that two samples from Quelana (Lineage 3) were recovered in polytomy with Lineage 1 (Puilar, Chaxa and Tebenquiche) and Lineage 2 (Tilopozo and the rest of the individuals from Tebenquiche).…”

“…The mitochondrial diversity indices obtained for the populations of Heleobia of the Atacama Saltpan were substantially lower than those reported in other Heleobia species that present fragmented populations (Valladares et al, 2018). On the other hand, the genetic distances between systems (COI sequences) were comparable to previous studies in closely related species of Heleobia and that also used mitochondrial information (Collado et al, , 2016b.…”

“…The amplification was performed by polymerase chain reaction (PCR) considering three mitochondrial markers and three nuclear markers. The methodology applied followed the protocols of Collado and Méndez (2012) and Valladares et al (2018). The details of the markers and primers used in the study are shown in Supplementary Table 1.…”

Hidden diversity in waterfall environments: The genus Acrorbis (Gastropoda: Planorbidae) from the Upper-Paraná Atlantic Forest

“…Similar evidence of microevolutionary differentiation at small spatial scale has already been documented for other South American endemic freshwater snails (e.g. [59,60]). Further research based on a greater number of individuals and loci per locality is required to gain insights into the evolutionary history, and the spatio-temporal framework of the diversification of Acrorbis in the Upper-Paraná Atlantic Forest.…”

Length-weight relationships native fish of Southern Altiplano: Lauca National Park, Chile

“…The rainfalls occur only during summer, phenomenon called "Invierno Altipl anico" (Altiplanic Winter), and they reach less than 100 mm/year, intensifying during the cyclic climatic event called "El Niño" (Aceituno 1996). These environmental characteristics, added to historical volcanic activity have originated endemic flora and fauna highly adapted to these conditions (Vila et al 2013;Victoriano et al 2015;Valladares et al 2018).…”