Evolving in islands of mud: old and structured hidden diversity in an endemic freshwater crayfish from the Chilean hotspot

Pedro F Victoriano,Guillermo D’Elía

doi:10.1038/s41598-021-88019-8

Pedro F Victoriano, Guillermo D’Elía

Open Access

https://doi.org/10.1038/s41598-021-88019-8

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Abstract

Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil. Parastacus pugnax is a Chilean endemic distributed along 700 km of latitude in central-southern Chile from the Pacific coast to the Andean piedmont, which is intensively captured for consumption for local communities. Considering the habitat (wet meadows) and natural history (primary burrower, non-migrant) of the species, we tested a hypothesis of highly structured genetic diversity using mtDNA of 465 specimens gathered at 56 localities across the species range. The crown age of P. pugnax was estimated at 38 Ma, predating the main Andean uplift. The genetic variation of P. pugnax is large and geographically structured. In some cases, genetic groups do not match basin limits, suggesting a previous to current dynamic of basin evolution. The uncovered intraspecific main lineages have different demographic histories. A latitudinal cline in past effective population size reduction suggests environmental singularities with a glacial effect in the southern populations. We suggest adding morphologic and more genetic data in order to assess species limits. Our results contribute to improve future conservation actions for this taxon, providing basic information to delimit conservation units.

Highlights

Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil
Current spatial patterns of genetic variation have largely resulted from the role played by habitat discontinuities e.g.4 and the historical stability of habitats, which in turn is influenced by episodes of past climate change[5,6]
The largest phylogenetic diversity is concentrated in Chile where the three South American genera (Parastacus, Virilastacus, and Samastacus) are present, summing seven species

Summary

Introduction

Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil. The main barrier effect of the austral Andes was the biogeographic and climatic divorce between the eastern and the Chilean slopes, in the Chilean side it added a high roughness, conforming many river basins and transverse ranges, which for many species represent numerous interrupted habitats, distributed along a steep climatic gradient. Over these complex landscapes, several glacial events took place from the latest Miocene 13 species of Parastacus are distributed within eastern South America in southeastern Brazil, northeastern Argentina, and Uruguay[28] This distributional pattern suggests that the basal radiation of Parastacus predates the Andean uplift

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