Evidence of Predation and possible competition among three semi aquatic species, the endangered Pyrenean desman (Galemys pyrenaicus), the aquatic shrew (Neomys fodiens) and the European otter (Lutra lutra) using next-generation sequencing methods from faeces

The Pyrenean desman (Galemys pyrenaicus) is a small-endangered semi-aquatic mammal endemic to the Pyrenean Mountains and to the northern half of the Iberian Peninsula whose ecology and biology are still poorly known. Its ecological relationships with other semi aquatic mammals like the aquatic shrew (Neomys fodiens) or the European otter (Lutra lutra) are also unknown. The aim of this study was to analyse Pyrenean desman, aquatic shrew and European otter faeces from the same French Pyrenean regions, in order to analyze their respective diets and to detect possible predation or competition patterns among them. To study precisely their diet, we used next-generation sequencing methods (Ion Torrent or Ilumina miseq technologies). We amplified and sequenced a small DNA minibarcode (133bp) of the COI gene in 445 faeces samples from the three species. In the Pyrenean desman faeces, we were able to identify a large set of prey species with a positive match (more than 98% of identity with a reference sequence). These species belonged to four orders and eleven families among which Trichoptera and Hydropsychidae were the most frequent, respectively. The aquatic shrew diet evidenced similar aquatic preys as compared to the Pyrenean Desman. However, it also evidenced an important part of terrestrial invertebrates like woodlouse, ants, coleopters or myriapods. The otter diet was mainly constituted of fishes (eg. Cyprinidae, Salmonidae). However, several faeces samples evidenced Pyrenean Desman DNA, strongly suggesting that otter predate Pyrenean Desman in the studied areas. Future studies will be developed on a better sampling from these three species, in order to gain a better knowledge of their local diets and their ecological relationships. Such information is of great importance to propose the best management measures for the conservation of these protected species.