Species composition of introduced and natural minnow populations of the Phoxinus cryptic complex in the westernmost part of the Po River Basin (north Italy)

Abstract

Invasive alien species are a major driver of biodiversity loss, with their impacts potentially more intense when complexes of cryptic species are involved. In freshwaters, the anthropogenic manipulation of fish communities has resulted in altered fish communities, and in Europe has increased the complexity of Phoxinus species assemblages. Here, we investigated the Phoxinus communities of the westernmost part of the Po river basin, where adjacent freshwater ecosystems (Alpine high-altitude lakes and lowland streams) are representative of different management strategies (i.e. manipulated fish communities via stocking in Alpine lakes vs. natural populations in streams). We tested the genetic composition of the cryptic Phoxinus populations inhabiting these waters, as the species are morphologically indistinct. Sequences of the mitochondrial cytochrome oxidase I (COI) were obtained from 239 specimens, with the results indicating that 17 Alpine high-altitude lakes are now populated by a complex of Phoxinus species, comprising P. septimaniae (native to the Mediterranean area of France), P. csikii (native to the Central Balkans) and P. lumaireul (native to the North Adriatic Sea basins). Their introduction resulted from their use as angling live baits. Minnow populations in lowland streams were primarily comprised of native P. lumaireul, with only a single P. csikii specimen detected. While nuclear sequences of the recombination activating gene 1 (RAG1) marker were not useful for tracking the presence of alien alleles in these stream populations, the COI data emphasised the importance of using molecular tools to investigate cryptic species complexes that have been modified by anthropogenic activities.

Evaluation of visual encounter surveys as a method for the rapid assessment of fish presence and relative density in high mountain lakes

“…Third, VES can be used to describe the distribution of cyprinids in mountain lakes. VES could help in describing this subtle invasion, which is advancing almost unnoticed over large mountain regions (Miró & Ventura, 2015; De Santis et al, 2021).…”

A new set of microsatellite markers for Phoxinus lumaireul senso lato, Phoxinus marsilii and Phoxinus krkae for population and molecular taxonomic studies

“…It is already known that Phoxinus species have been translocated and stocked, which caused hybridization zones in Spain, France, Italy, Germany and Austria (Corral‐Lou et al ., 2019; Denys et al . 2020; De Santis et al ., 2021; Palandačić et al ., 2020; Palandačić et al ., 2022). On the contrary, hybridization events within the Phoxinus genus in the Western Balkans are thought to be the result of evolutionary history of the area (Palandačić et al ., 2020).…”

The Complete Mitochondrial Genome of Eurasian Minnow (Phoxinus cf. Phoxinus) from the Heilongjiang River, and Its Phylogenetic Implications

“…Among the molecular markers used to study Phoxinus , the cytochrome oxidase subunit I (COI) gene encoded by mitochondrial DNA (mtDNA) seems to be the most successful [ 17 , 18 ] and has been generally used as a DNA barcode [ 19 , 20 ]. The application of molecular markers not only revealed substantial hidden diversity of Phoxinus , but also facilitated studies of geographical patterns, including invasion and diffusion patterns of the genus [ 18 , 21 , 22 ]. However, relevant studies on the molecular phylogeny and species delimitation of Phoxinus were mainly focused on European populations, and Asian populations have received less attention and have rarely been compared with European relatives.…”