Zoological Studies

Vol. 53, 2014

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

Gonzalo A Collado1*, Hugo F Salinas2 and Marco A Méndez2

1Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad del Bío-Bío, Casilla 447, Chillán, Chile
2Laboratorio de Genética y Evolución, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Chile

Background: The isolated watersheds of the southwestern Andean Altiplano constitute a natural laboratory to study the evolutionary divergence of freshwater biota. Field observations showed that Biomphalaria snails from Parinacota, Colpa, and Caquena have different shell sizes. We performed morphometric analysis and common garden 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.
Network analysis revealed that the snails of Parinacota form a lineage genetically distinct from Caquena and Colpa. The morphometric analysis of the shell showed that the Parinacota snails were larger than Caquena and Colpa, both in nature and laboratory conditions, but there was no evidence of difference in the shape of the shell when compared using multivariate analyses. The number of eggs per ovicapsule was the only life history trait that was 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 at
the locality level, not lineages.

Conclusions: The results suggest that shell size of the snails has a genetic basis associated to the phenotype, while the expression and evolution of life history traits in extreme high environments are highly influenced by proximal causes.

Key words: Planorbidae; Biomphalaria; Haplotype network; Shell morphology; Local adaptation; Chilean Altiplano.

*Correspondence: E-mail: collado.gonzalo@gmail.com