Brown trout (Salmo trutta L.) high genetic diversity around the Tyrrhenian Sea as revealed by nuclear and mitochondrial markers

Abstract

The brown trout (Salmo trutta L.) is widely distributed all around Europe but its natural diversity is 19 threatened by massive stocking with Atlantic domestic strains. Describing the remaining natural genetic 20 diversity and the proportion of domestic hatchery strains in rivers is a prerequisite for smart conservation. 21 The high genetic diversity of brown trout populations around the Tyrrhenian Sea is well known. Use of 22 twelve microsatellites has allowed description of the natural genetic structure of populations and detection 23 of the consequences of stocking. Mitochondrial DNA control region sequences and the LDH-C1* gene 24 enabled placement of each population into one of the six mitochondrial and two allozymic known 25 2 evolutionary lineages. The Corsican populations showed low intra-population genetic diversity but an 26 exceptionally high level of inter-population differentiation. More southern Tyrrhenian regions exhibited 27 opposite pattern of diversity, partly due to the Atlantic domestic introgression. Globally, the natural 28 structure outlines two north-south clines: high inter-population differentiation and predominance of the 29 Adriatic lineage in the north, but lower inter-population differentiation and presence of the natural Atlantic 30 lineage in the south. In addition, the Tyrrhenian region is the contact zone between the widespread 31 Adriatic lineage and a local natural Atlantic lineage probably coming from North Africa through the Strait 32 of Gibraltar.

Native bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix populations in the Pearl River are threatened by Yangtze River introductions as revealed by mitochondrial DNA

“…Meanwhile, a wide‐range survey focusing on the genetic resources of native Pearl River bighead and silver carp based on both mtDNA and nuclear markers ( e.g ., microsatellites, SNPs, nuclear genes) was proposed, as performed in the Yangtze River and Western Europe. This kind of survey is fundamental to the establishment of national aquatic germplasm reserves for economically important species (Berrebi et al ., ; Geng et al ., ; Li et al ., ; Splendiani et al ., ; Vera et al ., ; Wang et al ., ) and determines whether admixture occurs or whether the Yangtze‐origin haplotypes are from released individuals. In the future, fish from the Pearl River should be used to preserve the genetic diversity of native carp populations.…”

Genetic changes caused by restocking and hydroelectric dams in demographically bottlenecked brown trout in a transnational subarctic riverine system

“…Due to widespread anthropogenic habitat destruction across the distribution range of the Eurasian brown trout, as well as the long-term practice of translocations and stocking, natural and genetically unaltered trout populations are becoming increasingly rare (Araguas et al, 2009(Araguas et al, , 2017Baric et al, 2010). Although brown trout as a species is not endangered, harvest, translocations, and stocking have heavily altered natural populations, and it is therefore crucial to preserve remaining wild populations in order to retain the full spectrum of intraspecific genetic and ecological diversity (Berrebi et al, 2019;Piccolo et al, 2017). The Pasvik River is one of the largest and most species-rich subarctic river systems in northwestern Eurasia, with partially remaining wild brown trout populations; conservation of these natural populations is important to preserve unique genetic diversity in the region.…”

“…The Pasvik River is one of the largest and most species-rich subarctic river systems in northwestern Eurasia, with partially remaining wild brown trout populations; conservation of these natural populations is important to preserve unique genetic diversity in the region. Although brown trout as a species is not endangered, harvest, translocations, and stocking have heavily altered natural populations, and it is therefore crucial to preserve remaining wild populations in order to retain the full spectrum of intraspecific genetic and ecological diversity (Berrebi et al, 2019;Piccolo et al, 2017).…”

“…Targeted studies of how anthropogenic disturbances, such as hydropower developments, and mitigating actions, such as stocking, work in concert to affect the genetic integrity of natural populations are warranted to support long-term conservation goals in brown trout and other species facing similar challenges (Araguas et al, 2009(Araguas et al, , 2017Baric et al, 2010;Berrebi et al, 2019;Piccolo et al, 2017). In this study, we used brown trout as a model species and compared genetic diversity and differentiation patterns along a transnational subarctic riverine system that has been partitioned by hydroelectric power dams, and that additionally is regularly stocked with fish in parts of the river system but not in others.…”

Genetic structure of important resident brown trout breeding lines in Poland

“…Examples of mixed genetic lines can be also found in almost all European countries (e.g. Almodóvar et al 2006;Apostolidis et al 1996;Berrebi et al 2019;Fruciano et al 2014;Largiadèr and Scholl 1995). Numerous studies have addressed the fitness of salmonid hatchery fish in comparison with native stocks, and their performance has usually been determined as worse than that of original stocks.…”