Genetic, morphological, and life history traits variation in freshwater snails from extremely high environments of the Andean Altiplano

Abstract

Background:The isolated watersheds of the southwestern Andean Altiplano constitute a natural laboratory tostudy the evolutionary divergence of freshwater biota. Field observations showed thatBiomphalariasnails fromParinacota, Colpa, and Caquena have different shell sizes. We performed morphometric analysis and commongarden experiment to evaluate whether the observed shell variation has a genetic base and if this variation ismanifested in other morphological characters and life history traits.Results:Network analysis revealed that the snails of Parinacota form a lineage genetically distinct from Caquenaand Colpa. The morphometric analysis of the shell showed that the Parinacota snails were larger than Caquena andColpa, both in nature and laboratory conditions, but there was no evidence of difference in the shape of the shellwhen compared using multivariate analyses. The number of eggs per ovicapsule was the only life history trait thatwas significantly different between lineages, although this difference may be also attributed to size of the progenitor;the oviposition rate did not differ between lineages or localities, and the hatching size and growth rate differed only atthe locality level, not lineages.Conclusion:The results suggest that shell size of the snails has a genetic basis associated to the phenotype, while theexpression and evolution of life history traits in extreme high environments are highly influenced by proximal causes.