Preliminary genetic structure of the endemic Montseny brook newt, Calotriton arnoldi inferred from mtDNA and nDNA

Abstract

The Montseny brook newt Calotriton arnoli, endemic to the Montseny massif (NE Iberian Peninsula), is catalogued as critically endangered by the IUCN. This rare and threatened species inhabits oligotrophic, cold (below 15°C) fast running brooks. Given its small population size and small distribution area, management measures should be considered. Genetic studies are a very useful tool and therefore are widely implemented in many conservation programs. Two mitochondrial (ND4 and Cyt b) and one nuclear (RAG-1) marker from 105 individuals were used to infer the population genetic structure and phylogeography of this species, covering its total distribution range. Both mitochondrial and nuclear markers confirm the differentiation between C. asper and C. arnoldi. Moreover, haplotype networks and analysis of molecular variance suggest that two distinct groups of populations can be differentiated within C. arnoldi. This is in concordance with morphological differentiation, and correlates with its geographical distribution, as the two groups are situated on each side of the Tordera river valley. Glaciations occurred during the lasts periods may have forced the species to retreat into these two isolated areas, with a subsequent extinction of the in-between populations. The limited dispersion capability owing to its totally aquatic behaviour caused the isolation of these two groups of populations, and the consequent independent evolution. Thus, these results strongly justify the management of this species as two independent ESU’s (Evolutionary Significant Units) to guarantee the long-term population viability.